Mullerian Duct Anomalies

Developmental anomalies of the müllerian duct system represent some of the most fascinating disorders that obstetricians and gynecologists encounter. The müllerian ducts are the primordial anlage of the female reproductive tract. They differentiate to form the fallopian tubes, uterus, uterine cervix, and superior aspect of the vagina. A wide variety of malformations can occur when this system is disrupted. They range from uterine and vaginal agenesis to duplication of the uterus and vagina to minor uterine cavity abnormalities. Müllerian malformations are frequently associated with abnormalities of the renal and axial skeletal systems, and they are often the first encountered when patients are initially examined for associated conditions.

Most müllerian duct anomalies are associated with functioning ovaries and age-appropriate external genitalia. These abnormalities are often recognized after the onset of puberty. In the prepubertal period, normal external genitalia and age-appropriate developmental milestones often mask abnormalities of the internal reproductive organs. After the onset of puberty, young women often present to the gynecologist with menstrual disorders. Late presentations include infertility and obstetric complications.

Because of the wide variation in clinical presentations, müllerian duct anomalies may be difficult to diagnose. After an accurate diagnosis is rendered, many treatment options exist, and they are usually tailored to the specific müllerian anomaly. ^{[1, 2]}

Refinements in surgical techniques, such as the Vecchietti and McIndoe procedures, have enabled many women with müllerian duct anomalies to have normal sexual relations. Other surgical advances have resulted in improved fertility and obstetric outcomes. In addition, developments in assisted reproductive technology allow some women with müllerian duct anomalies to conceive and deliver healthy babies.

As a foundation for understanding müllerian duct anomalies, the first part of this article discusses the epidemiology and classification of müllerian duct defects as well as normal embryologic development of the female reproductive tract. The remainder of the article concentrates on the latest methods of surgical management for these disorders.

References regarding the existence of müllerian defects date back to antiquity, around 300 BC. Columbo reported the first documented case of vaginal agenesis (uterus and vagina) in the 16th century. ^[3] Our knowledge of their epidemiology has not paralleled the technical advances involved in their diagnoses and treatment.

The actual incidence and prevalence of müllerian anomalies in the general population are unknown. Considerable selection bias has impeded the collection of accurate epidemiologic data. Uterine abnormalities are frequently unrecognized at birth and are unreported. However, during childbearing years, when reproductive malfunctions occur, they are over reported. Other factors that affect reporting irregularities in incidence and prevalence rates include nonstandardization of classification systems, nonuniform diagnostic modalities, and different study populations of women.

Incidence rates vary widely and depend on the study. Most authors report incidences of 0.1-3.5%. ^{[4, 5, 6]} In 2001, Grimbizis and colleagues reported that the mean incidence of uterine malformations was 4.3% for the general population and/or for fertile women. ^[7] This rate was determined by reviewing data compiled from 5 studies that included approximately 3000 women with uterine malformations. In women with fertility problems, the incidence of müllerian duct anomalies is slightly higher at 3-6%. In general, women with recurrent abortions have an incidence of 5-10%, with the highest incidence of müllerian defects occurring in patients having third-trimester miscarriages. ^{[8, 9]} The most commonly reported müllerian duct anomalies are septate, arcuate, didelphys, unicornuate, or hypoplastic uteri. The exact distribution depends on the study and on the geographic location. ^{[8, 10]}

The prevalence of müllerian duct anomalies also varies significantly, with reports ranging from 0.16-10%. ^{[11, 12, 13, 14]} When these data are obtained in women with recurrent pregnancy loss who are undergoing hysterosalpingography (HSG), the prevalence of müllerian anomalies is 8-10%. ^{[11, 12]} This rate contrasts with a prevalence of 2-3% in women undergoing elective hysteroscopy, a population thought to better reflect the general population than the former group. ^[15] However, a Danish study of 622 women (aged 20-74 years), all of whom were examined with saline contrast sonohysterography, suggested the prevalence of müllerian duct anomalies in the general population to be 9.8%; the prevalence was particularly high in nulliparous women and in those with oligomenorrhea. ^[16]

Grimbizis et al also reported on prevalence, which was about 4.3% for the general population and/or fertile women, about 3.5% in infertile women, and about 13% in women with recurrent pregnancy losses. ^[7] Byrne and colleagues reported a prevalence of approximately 4 müllerian defects per 1000 (0.4%) women in their prospective study of 2065 women aged 9-93 years who underwent consecutive sonographic examinations for nonobstetric indications. ^[14] Although this study may provide a baseline estimate of the prevalence of müllerian duct anomalies, ultrasonographic studies do not accurately depict all types of müllerian defects. Therefore, this report may underestimate the actual prevalence rates.

With the emergence and widespread use of highly sensitive imaging technologies, in addition to the development of a standardized classification scheme, confounders may play a lesser role in future reports. The incidences and prevalences reported for a given anomaly in this article reflect these considerations.

Normal development of the female reproductive tract involves a series of highly orchestrated, complex interactions that direct differentiation of the müllerian ducts and urogenital sinus (UGS) to form the internal female reproductive tract. Although they originate from different germ layers, the developmental fate of the müllerian ducts (mesoderm) and UGS (endoderm) are interconnected. The müllerian ducts are the primordial anlage of the internal female reproductive organs and differentiate to form the fallopian tubes, uterus, uterine cervix and superior aspect of the vagina. The UGS is thought to give rise to the inferior and mid vagina.

When an interruption or dysregulation occurs in any of the dynamic processes of differentiation, migration, fusion, and canalization, a wide spectrum of müllerian duct anomalies can result. ^[17] Of importance, other defects frequently accompany müllerian abnormalities. The developing kidney and urinary system are closely related to the reproductive tract and their abnormalities are often associated with defects in the reproductive system. Disruption of the developing local mesoderm and its contiguous somites accounts for some associated axial skeletal abnormalities. Developmental anomalies of the lower gastrointestinal tract have also, albeit rarely, been associated with müllerian defects. A retrospective study conducted on 46XX genetic females with cloacal exstrophy indicated a large majority (87%) had accompanying müllerian anomalies. ^[18] Another retrospective study on young female patients with imperforate anus similarly reported a majority (80%) had müllerian defects, specifically vaginal atresia. ^[19]

Cardiac and auditory deficits have occasionally been described. Ovarian morphogenesis occurs through different developmental events and is independent of müllerian duct differentiation. Thus, in females with müllerian duct anomalies, the ovaries and their endocrine function are usually normal. ^[17]

Development of the fallopian tubes, uterus, and uterine cervix

At 6 weeks of development, both female and male embryos have 2 sets of paired genital ducts: the müllerian (paramesonephric) ducts and the wolffian (mesonephric) ducts. Their genital systems are morphologically identical at this indifferent phase, though cellular differences are already present. ^[20] Development of the wolffian ducts precedes development of müllerian ducts. For a short period, the wolffian ducts drain the contents of the primitive mesonephric kidney into the cloaca, but they soon regress. ^[21]

In the female, the wolffian ducts degenerate in the absence of testosterone. ^{[22, 6]} At the same time, the müllerian ducts develop bidirectionally along the lateral aspects of the gonads; the regressing vestiges of the wolffian ducts provide a template for the developing müllerian ducts. It is this primordial, shared connection that explains the frequent associations observed later between müllerian defects and renal-urinary system malformations.

The müllerian ducts originate as longitudinal invaginations of coelomic epithelium on the anterolateral surface of the urogenital ridge. ^[21] They elongate at week 9, with 3 recognizable regions: cranial vertical, horizontal, and caudal vertical. ^{[23, 24, 21]} Each region has a distinct fate in the formation of the female reproductive tract.

The funnel-shaped cranial regions open directly into the primitive peritoneal cavity and remain separated. They form the fimbria of the fallopian tubes. The horizontal regions migrate, course laterally to the wolffian ducts, cross ventrally, and then extend caudomedially. They form the remaining structure of the fallopian tubes. Each caudal-vertical region intimately contacts its contralateral partner at the median plane of the future pelvis. The paired müllerian ducts, initially separated by a septum, fuse and form a single Y -shaped tubular structure, the uterovaginal primordium (UVP). ^{[23, 24, 21]}

The traditional hypothesis maintains that the müllerian ducts are fused in a caudal-cranial direction. However, the müllerian anomaly characterized by a septate uterus, cervical duplication, and longitudinal vaginal septum supports the alternative hypothesis in which fusion of the müllerian ducts is segmental and bidirectional. ^{[25, 26]}

The UVP consists of a uterine and a vaginal region. The uterine region gives rise to the uterus and the vaginal region, the superior third of the vagina. ^{[23, 21, 6]} At this stage, the uterus is bicornuate, but is developmentally plastic. It continues to differentiate by means of fusion and subsequent canalization of the intervening septum. Apoptosis, which the bcl -2 gene regulates, may mediate regression of the uterine septum. ^[27] By week 12, the fundus rises, and the uterus assumes its mature morphologic pear shape. The uterine endometrium is derived from the lining of the fused müllerian ducts, whereas the endometrial stroma and myometrium are derived from adjacent mesenchyme. ^{[23, 21]} This entire process is completed by the 22nd week of development and results in the formation of 2 fallopian tubes, a single uterus, the uterine cervix, and the upper vagina. ^[6]

Development of the vagina and hymen

Normal vaginal development requires the fusion of components that are derived from 2 embryologic structures: the mesodermal müllerian ducts and the endodermal UGS. The caudal tip of the UVP inserts into the dorsal wall of the UGS, the bladder anlage, forming the müllerian or sinus tubercle. The sinus tubercle in turn induces the formation of the sinovaginal bulbs at its distal aspect. The sinovaginal bulbs are paired endodermal evaginations. They extend as a solid core from the UGS to the caudal aspect of the UVP, fuse, and form the vaginal plate. The vaginal plate and the sinovaginal bulbs restructure the long tubular UGS into a flat vestibule. The restructuring allows for the proper positioning of the female urethra at the primitive perineum. The vaginal plate simultaneously canalizes in the process of desquamation to form the vaginal canal. Canalization is complete by week 20.

The fibromuscular wall of the vagina develops from the surrounding mesenchyme. The definitive boundary between the contributing components of the UVP and UGS is still a matter of controversy. Some authorities maintain that the superior third of the vaginal epithelium is derived from the UVP and the inferior two thirds, the UGS. Data support this hypothesis. Uroplakin, a specialized urothelial membrane protein, was immunohistochemically detected in the dorsal wall of the UGS evagination in the lower genitourinary tracts of 9-18 week human female fetuses. ^[28] Other experts consider the entire vaginal lining to be derived from the vaginal plate of the UGS. ^{[29, 21]}

The vaginal hymen is a vestige of the endodermal membrane that differentiates into the vaginal vestibule. It separates the vaginal lumen from the UGS cavity and is formed by caudal expansion of the vagina with subsequent invagination of the posterior wall of the UGS. ^{[5, 20, 21]} The hymen usually ruptures perinatally and remains as a thin mucous membrane. ^[30]

The above stated developmental events are the traditional and accepted processes by which the female reproductive tract is formed during development. As we become increasingly aware of various developmental defects that manifest as müllerian anomalies, we must be prepared to challenge current paradigms. Although more recent data are contrary to commonly accepted theories, they support early 20th century studies by Hart (1901) ^[31] and Mijsberg (1924), ^[32]  who individually identified the sinovaginal bulbs as being derived from the caudal aspects of the wolffian ducts and the müllerian ducts. These bulbs were designated as wolffian bulbs.

In 2002, Drews and coworkers reported that, in mouse models, the entire vagina arises from the downward growth of wolffian and müllerian ducts and that the sinovaginal bulbs are formed by the caudal wolffian ducts. They also concluded that in the mouse vaginal development is under negative control of androgens. ^[33] Similar observations in an analysis of human embryos support these findings. The embryos ranged from Carnegie stage 18 to 23. In all 7 examined embryos, the caudal müllerian duct was intimately connected to the wolffian duct by a common basal membrane and the caudal aspect of the fused müllerian duct separated and returned to the respective wolffian ducts. ^[34]

Intriguingly, Acien and colleagues described an exceptional case of a 25-year-old woman presenting with complex urogynecologic malformations that suggested both a wolffian duct and sinus tubercle origin for the vagina. The patient had a didelphys uterus, unilateral cervical-vaginal atresia, and ipsilateral renal agenesis. During hemihysterectomy, the atretic hemicervix was found to open into another atretic duct, and it continued inferiorly to terminate at the existing normal vagina. It was the authors' conclusion that their operative discovery, together with the histopathologic findings, suggested a role for the wolffian ducts in vaginal formation. ^[35]

Kurita conducted a study in mice on the developmental origin of vaginal epithelium. After immunofluorescence labeling studies of the müllerian duct, wolffian duct, and urogenital sinus, the author concluded that adult mouse vaginal epithelium is derived exclusively from müllerian duct epithelium. ^[36]

Throughout time, various classification schemas have been proposed for müllerian duct anomalies. ^{[37, 38, 39]} However, no single classification schema definitively categorizes the wide range of malformations. The most contemporary and widely utilized classification system is the one published by the American Fertility Society (AFS) in 1988. ^[40]

The AFS schema categorizes müllerian anomalies according to the major uterine anatomic defect and allows for standardized reporting methods for clinicians. It contrasts with a number of historical classification systems, as well as those of contemporary authors, that frequently group the anatomic defects according to the failed developmental mechanism that gives rise to a given malformation. ^{[41, 42]}  Other classification systems have been proposed, each with acknowledged merits. Indeed, classification systems will continue to be modified as our understanding of the malformations progresses, together with advancements and refinements in diagnostic modalities and surgical techniques.

The American Society of Reproductive Medicine (ASRM) Task Force on Müllerian Anomalies Classification modified the AFS classification. ^[43]  The classification was revised and expanded to include a wider range of müllerian anomalies that had been previously omitted. Vaginal septum defects—longitudinal and transverse—along with a wide array of complex anomalies are now included in the schema. Furthermore, the scope has been broadened to include overlap among the various descriptive categories.

The current ASRM (2021) müllerian anomalies classification includes the following nine descriptive designations and replaces the AFS (1988) numerical nomenclature ^[43] :

• Müllerian agenesis
• Cervical agenesis
• Unicornate uterus
• Uterus didelphys
• Bicornuate uterus
• Septate uterus
• Longitudinal vaginal septum
• Transverse vaginal septum
• Complex anomalies

In the following sections, the surgical management of each müllerian duct anomaly is discussed and organized according to the ASRM (2021) classification. ^[43]  Most of these anomalies are extremely rare, the data are scarce, and definitive management strategies have not been established.

Müllerian agenesis, also termed müllerian aplasia, is characterized by an absence or hypoplasia of the uterus, proximal vagina, and, in some cases, the fallopian tubes. ^{[44, 45]}  The condition has been also referred to as the Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, when it occurs in its most extreme form, both uterine and vaginal aplasia.

Müllerian agenesis is an uncommon, but not rare, anomaly. It occurs in an estimated 1 in 5000 newborn females. ^{[46, 45]}  The general obstetrician and gynecologist can expect to encounter this condition once or twice during their career. Multiple variants, some with complicated associated anomalies, have been reported. In approximately 7-10% of women with müllerian aplasia, a normal but obstructed uterus, or a rudimentary uterus with functional endometrium, is present. ^{[47, 48]}

Müllerian agenesis can be partial or complete. Partial müllerian agenesis is more rarely encountered and is characterized by a normal uterus and small vaginal pouch distal to the cervix. Complete müllerian agenesis (MRKH syndrome) is the most common variant encountered, and it is characterized by congenital absence of the vagina and the uterus in 90-95% of cases. The fallopian tubes are normal, and the ovaries have normal endocrine and oocyte function. ^[49]

Müllerian ageneis can be an isolated finding, although associated anomalies often coexist. The incidence of associated urologic abnormalities ranges between 15% and 40%, and skeletal anomalies, such as congenital fusion or absence of vertebrae, occur in approximately 12-50% of cases. ^{[50, 51]}  An association between MRKH syndrome and Klippel-Feil syndrome has been reported. This syndrome is characterized by congenital fusion of the cervical spine, a short neck, a low posterior hairline, and limited range of motion in the cervical spine. ^[52]  The MURCS association (ie, M üllerian duct aplasia, U nilateral R enal aplasia, C ervicothoracic S omite dysplasia) is another variant. Infrequently, auditory deficits, cardiac defects, and other abnormalities can be found. ^[53]

The etiology of müllerian agenesis is unclear. The wide spectrum of anomalies encountered in this anomaly suggests a field defect involving closely related structures derived from intermediate mesoderm. Most cases occur sporadically, although the rising number of reported familial cases indicates a genetic etiology. The karyotype of females having müllerian aplasia is 46,XX. Approximately 4% of reported cases are familial, with affected siblings, and in some cases it is transmitted as an autosomal dominant trait. ^[54]  As an example, one report described müllerian aplasia in three siblings and their two paternal aunts. ^[55]

Müllerian agenesis has been associated with variants of the galactose-1-phosphate uridyltransferase (GALT) enzyme; this finding suggests that increased exposure to galactose is responsible for abnormal vaginal development. ^[56]  However, analysis of the gene encoding GALT failed to reveal any mutations or polymorphisms associated with müllerian aplasia. Similar findings were also true for another candidate gene encoding the cystic fibrosis transmembrane regulator chloride channel. ^{[57, 58]}

Other authorities have speculated that mutations in either the antimüllerian hormone or müllerian inhibitory substance (MIS) gene or its receptor gene are responsible for this disorder. ^[22]  This theory has been subsequently disregarded after data from a genetic study involving 22 females with müllerian agenesis failed to identify any gene mutations or sequence polymorphisms in the MIS gene or its receptor. Confounding these findings was the observation that DNA fragments from the participants were similar to DNA from the control population. ^[59]

One report discusses a de novo translocation in a young woman with MRKH syndrome, suggesting that this break point may be involved in midmüllerian differentiation. ^[60]  A loss-of-function mutation in the WNT4 gene was identified in an 18-year old woman with MRKH syndrome, unilateral renal agenesis, and androgen excess with virilization. The WNT4 gene encodes for a secreted protein that suppresses male sexual differentiation. In mice, the corresponding WNT4 protein is involved in development of the müllerian ducts. The described mutation in this patient indicated that an association between the WNT4 gene and müllerian duct differentiation may also exist in humans. ^{[61, 62]}

Early developmental control genes, homeobox HOXA9- HOXA13 and their DNA-binding transcription factors, have also been considered candidate genes involved in human müllerian aplasia based on similar phenotypes identified in mutant mice. In vertebrates, HOX genes direct early morphogenesis of the segmental body plan along the anteroposterior axis. ^{[63, 64]}  HOXA9 -HOXA13 genes specify the positional patterning of the fallopian tubes, uterus, uterine cervix, and upper vagina. ^[65]  However, no definitive defects have been identified in these genes that account for human müllerian aplasia.

The American College of Obstetricians and Gynecologists (ACOG) published their recommendations on the diagnosis, management, and treatment of müllerian agenesis, which are elucidated as follows ^[44] :

• Müllerian agenesis patients are mostly identified when evaluated for primary amenorrhea with otherwise typical growth and pubertal development.
• Magnetic resonance imaging (MRI) finds rudimentary müllerian structures in 90% of patients with müllerian agenesis. These structures are difficult to interpret on ultrasonography.
• Evaluation for associated congenital anomalies is necessary because up to 53% of patients with müllerian agenesis have concomitant congenital malformations, particularly of the urinary tract and skeleton.
• Müllerian agenesis patients should be offered counseling and encouraged to find peer support groups.
• There should be a discussion with patients concerning future options for having children.
• The first-line approach in most patients should be primary vaginal elongation by dilation. Compared with surgery, it is safer, patient-controlled, and more cost-effective.
• Surgery should be reserved for the rare patient who is unsuccessful with primary dilator therapy or who prefers surgery after a thorough informed consent discussion with her gynecologic care provider and her respective parent(s) or guardian(s). Primary vaginal dilation is successful for more than 90-96% of patients.
• Referrals to centers with expertise should be offered regardless of the surgical technique chosen. The surgeon must be experienced with the procedure because the initial procedure is more likely to succeed than follow-up procedures.
• Although vulvar and vaginal intraepithelial neoplasia are possible, routine cytology testing is not regularly recommended because of the lack of a cervix.
• Sexually active women with müllerian agenesis should be aware that they are at risk of sexually transmitted infections and, thus, condoms should be used for intercourse. Patients should be appropriately screened for sexually transmitted infections according to the guidelines for women without müllerian agenesis.
• Patients should be given a written medical summary of their condition, including a summary of concomitant malformations. This information may be useful if the patient requires urgent medical care or emergency surgery by a health care provider unfamiliar with müllerian agenesis.

Diagnosis of müllerian agenesis 

Müllerian agenesis is usually diagnosed at puberty when adolescents present to the gynecologist with primary amenorrhea. It is the second most common cause of primary amenorrhea in adolescents. ^[66]  Physical examination reveals normal growth and development with age-appropriate secondary sexual characteristics. External genitalia are normal. Examination of the external genitalia often reveals a patulous urethra. ^{[67, 60]}

Appearances of both introitus and vagina can vary significantly in young adolescents. The vaginal vault can be either completely absent or a short vaginal pouch can be present. Occasionally, a short vaginal dimple is present, located 1-2 cm superior to the hymenal ring. A uterus is not palpated on rectal examination. On pelvic examination, a smooth band that crosses the pelvis is sometimes appreciated and most likely represents a remnant of the uterosacral ligament.

Ultrasonographic findings can add support to the clinical findings, suggesting the absence of uterus and fallopian tubes in the presence of normal ovaries. MRI is extremely useful; absence of the vagina and uterus on a technically adequate image confirms the diagnosis of agenesis or hypoplasia. ^{[68, 69, 70]}  This modality can also depict a rudimentary uterus and any coexisting renal abnormalities. ^[71]

The hormonal profile is that of a normal female with age-appropriate luteinizing hormone, follicle-stimulating hormone, estradiol, and testosterone levels. This profile helps distinguish the MRKH syndrome from androgen insensitivity syndromes in which postpubertal testosterone is elevated.

Laparoscopy is not usually indicated unless the diagnosis cannot be determined based on findings from other studies or if the presence of a functioning uterus or rudimentary uterine tissue is a concern. Patients with these findings are not candidates for HSG.

Preoperative evaluation

Surgical and nonsurgical methods of treatment have been used. In accordance with the ACOG recommendations, the nonsurgical approach should be the first-line treatment. ^[44] It relies on the use of rigid dilators of progressively increased length and depth, so as to elongate and create a neovagina. This method may take several months or a few years before a functional vagina is formed. Surgery remains the most effective method of treatment for müllerian aplasia and should be performed by a highly skilled and experienced surgeon.

Choosing the proper time to perform a vaginoplasty is of paramount importance. Surgical treatment should be considered only when the patient can participate in the decision-making, wishes to become sexually active, and is highly motivated to use a vaginal prosthesis for several months after surgery. ^{[72, 73]}

Psychological support and counseling are essential components of the preoperative evaluation and care for many reasons. In addition to the inability to have sexual intercourse, these young women are usually infertile, resulting in psychological pain and self-esteem issues, often with a lasting negative impact. ^[74]  Since the ovaries are normal, oocyte harvesting can be conducted so that these women can have children with a surrogate, and these young women should be counseled about various reproductive options.

Routine preoperative evaluation should include intravenous pyelography (IVP) and renal sonography to exclude urinary tract anomalies. Associated skeletal defects can be detected by reviewing images from IVP radiographic studies for vertebral abnormalities. Although most findings are clinically insignificant, they should be noted in the medical record. Fusion of the cervical vertebrae, a component of Klippel-Feil syndrome, can result in cervical rigidity that may substantially interfere with the intubation procedure. ^[52]  If a pelvic mass is present, sonograms should help in differentiating hematometra, hematocolpos, ovarian cysts, and a pelvic kidney. ^[75]  Discovery of a pelvic kidney is important in planning corrective surgery because its presence may limit the potential space available for graft placement. ^[76]

Surgical techniques for müllerian agenesis (mullerian aplasia, vaginal agenesis)

The aim of surgical treatment is to create a neovagina. Although several vaginoplasty methods have been developed, refined, and modified, no definitive surgical approach has been established. This is due to a number of factors including regional differences, the surgeon’s experience and preference for a method, and the patient’s choice. ^[77]  Often, the procedure must be individualized.

The strategy for vaginoplasty is to develop a space between the bladder and the rectum. In some approaches, a stent or form is placed in the newly created space to ensure patency while healing occurs.

Skin grafting remains the most popular material used in vaginoplasties; however, scar formation at the graft site has been a concern. ^[78]  In the United States, full-thickness skin grafts are often used, and are associated with less graft contracture and stenosis compared with that of split-thickness grafts. ^[79]  However, the split-thickness skin graft has a high rate of success and patient satisfaction. ^{[80, 81]}  A variety of other tissues have been used as the graft source. Human amnion, not stripped from the chorion, has been used as a graft for vaginoplasties. ^[82]

Transposition flaps were described in two reports. In one method, a de-epithelialized vulvar transposition flap was used as the graft, and in the other, a pudendal thigh fasciocutaneous flap was described. Both authors reported good cosmetic and functional results. ^{[83, 84]}  Autologous buccal mucosa has also been used as a graft source. These approaches harvested bilateral full-thickness buccal mucosa grafts. After antiseptic is applied to the harvest sites, the grafts are expanded by using several stabs, incisions, and sutures over a condom-covered soft stent. They are then placed in the newly created space. ^[85]

The use of artificial dermis and absorbable adhesion barriers show promise as exogenous graft sources in vaginal reconstruction. In a case study by Noguchi and associates, a modified Warton method was used to create an artificial space between the bladder and rectum. An acrylic resin form was covered with artificial dermis, inserted, and fixed to the newly created vaginal space. The form was left in place for 7 days and then removed. The authors reported good results with continued use of the form at nighttime. ^[86]

Motoyama and colleagues described a similar technique using absorbable adhesion barrier (Interceed; Ethicon, Somerville, NJ). They reported neovaginal epithelization in 1-4 months. All 10 patients were satisfied with the results. ^[87]  In an early study, this absorbable adhesion barrier was also used in place of a skin graft in vaginoplasty in 4 patients with MRKH syndrome; no complications were reported. ^[88]

Some pediatric surgeons prefer using a bowel segment in place of a skin graft. Indeed, bowel vaginoplasty involving the distal sigmoid colon to line the neovaginal canal has gained popularity in some centers. This approach usually requires concomitant laparotomy and bowel anastomosis, although more recent reports describe a laparoscopic approach. ^{[89, 90, 91]}  Advantages of bowel vaginoplasty include no requirement for persistent dilation, a component of the postoperative therapy for the McIndoe procedure, and the neovagina is self-lubricating. ^[92]  Most nonskin grafts have been abandoned because of their association with increased morbidity, the development of leukorrhea, and other complications. Indeed, some experts believe that this approach should be reserved for those patients who have undergone prior, extensive genital reconstructive surgery. ^[93]

An innovative approach to vaginoplasty has been reported that included a 12-month post-procedure follow-up. In this study, 23 young women underwent a modified Abbe-McIndoe vaginoplasty using autologous vaginal tissue previously cultured in vitro. The neovaginas demonstrated normal length and depth with subsequent cytology and biopsy studies both indicating the presence of normal vaginal tissue. Moreover, at 1 year post surgery, the patients reported satisfactory quality of sexual experiences. The authors caution that larger studies with longer follow-up will be needed to determine whether this approach bears merit. ^[94]

The modified McIndoe procedure remains the most common surgical approach to vaginoplasty. Abbe originally described it in 1898. McIndoe modified it in 1938, as others did later. The procedure involves the following steps:

• Split-thickness grafting

  • Obtaining a satisfactory split-thickness graft is one of the most important steps in performing the modified McIndoe procedure. The graft harvested from each buttock should measure 8 × 9 cm, and excised to a depth of 0.045 cm (0.018 in). In total, the graft dimensions should measure approximately twice the vaginal depth.
  • The graft is usually taken from the buttocks. After prepping the graft site with antiseptic solution, a single layer is removed avoiding any variation in graft thickness. Many surgeons advocate using the pneumatic Padgett electrodermatome for this purpose.
  • After retrieval, the graft is placed between saline-moistened gauze and reserved for later use. After the donor sites are dressed, the patient is repositioned for the next step.
• Creation of the vaginal space

  • The goal is to create an adequate space between the urethra and/or bladder and the rectum without exposing too much peritoneum.
  • The patient is placed in the dorsal lithotomy position, and a transurethral catheter is placed to assist in defining the urethra-bladder anterior boundaries. A vasopressor solution is injected into and around the vestibule area, and a transverse incision is made in the mucosa at the apex of the vaginal dimple.
  • The dissection is initiated along 1 side of the midline, creating a small space in the fibroconnective tissue between the bladder and the rectum using blunt dissection. This process is repeated on the opposite side. The median raphe is divided with scissors, joining the spaces. The dissection is continued up to the peritoneum. It is importantly not to expose too much peritoneum because an enterocele can develop postoperatively.
  • Meticulous hemostasis is needed to avoid bleeding, which can cause the graft to separate from its bed and result in engraftment failure.
• Prosthesis assembly

  • The stent should be made from material that can maintain the patency of the vaginal cavity. A foam-rubber form measuring 10 × 10 × 20 cm works well.
  • The prosthetic device is sterilized, and the size is customized to fit the patient's vagina. The prosthetic material is cut to twice the desired size of the vagina, folded in half, and compressed by the placement of 2 condoms over the surface. The condoms are tied at the open end.
• Graft attachment to a prosthesis

  • The graft is placed over the stent with the epidermis approximating the surface of the stent and the dermis facing out. This graft is sutured over the form using 5-0 absorbable sutures.
  • The graft-covered prosthesis is carefully inserted into the vaginal canal.
  • The edges of the graft are sutured to the previously cut edges of the mucosal margins of the vaginal introitus. This contact is often adequate, rendering sutures unnecessary. If the contact between the graft and the vaginal space is too tight, serum may collect and compromise the engraftment.
  • The labia minora are sutured around the stent using nonreactive sutures.
  • To avoid applying too much pressure to the stented graft, the transurethral catheter is replaced with a suprapubic bladder catheter. ^{[76, 67, 46, 95]}

Postoperative management

The patient is prescribed antibiotics and a low-residue diet. She is gradually allowed to ambulate within 24 hours after surgery, but she must remain on bedrest in upright and flat positions for 1 week. The suprapubic catheter can be removed after the patient is voiding well. One week after surgery, the labial sutures are removed, and the stent is carefully removed with the patient under mild sedation. The neovagina is irrigated with warm sodium chloride solution and carefully inspected to determine whether the graft has taken satisfactorily. A new form covered with a sterile sheath is reinserted.

Patient education regarding the importance of continuous, prolonged dilatation and stent care during the healing phase is important. ^[75]  The form is worn continuously for 6 weeks and is removed only for urination and defecation. Low-pressure douches with warm water are performed daily. At the same time, the form is cleaned with a povidone-iodine solution, covered with a fresh condom, lubricated, and reintroduced into the neovagina. After 6 weeks, a silicone form that is inserted nightly for the next 12 months replaces the original stent. In most cases, the vagina is functional 6-10 weeks after surgery. ^{[95, 76, 67, 46]}

Surgical complications and results

Refinements in surgical techniques, greater surgical experience, and improvements in postoperative care have resulted in fewer complications and excellent graft function. Percentages of patients reporting satisfactory results range from 80-100%. ^{[80, 96]}  Serious complications can occur and include postoperative fistula (4% risk) and, in rare cases, enterocele. ^{[41, 76, 46]}  Postoperative infection, hemorrhage, and graft failure are occasionally encountered. Contracture of the graft and the development of excess granulation tissue sometimes occur. ^{[76, 46]}

Primary malignancy of the neovagina has been reported to occur in exceptionally rare cases; for this reason, yearly Pap smears are recommended as part of long-term follow-up care. ^{[97, 98]}

In summary, the McIndoe procedure is the most widely accepted surgical approach to müllerian aplasia. It is a highly successful procedure, and patient satisfaction is high. Although most patients cannot obtain full fertility, except through surrogates, they can have normal sexual relations.

Alternative surgical strategies

The Williams vulvovaginoplasty is an alternative to the McIndoe procedure. This procedure is particularly useful for patients with previously failed vaginoplasty or patients who have undergone radical pelvic surgery. It uses full-thickness skin flaps from the labia majora to create a vaginal pouch. Unlike the McIndoe procedure, vaginal dilation is required for only 3-4 weeks. The vagina created by this approach is not anatomically similar to a normal vagina or the neovagina created by the McIndoe procedure. Instead, the vaginal pouch axis is directly posterior and horizontal to the perineum; however, the vagina is functional and well received by patients. Fistula formation, which can occur with the McIndoe procedure, is rare. ^[99]

Laparoscopic procedures

Alternative vaginoplasty methods have been developed and refined and are achieving increasing success. The laparoscopic approach has augmented surgical approaches for neovaginal creation. Two such methods are discussed below.

The Vecchietti operation, developed in 1965, requires the use of a specifically designed traction device that is placed on the outer surface of the abdomen. Through laparotomy, sutures attached to the device enter and course through the abdominal cavity and at their termination connect to an elliptically shaped plastic bead located at the introital area. The device permits upward traction on the retrohymenal fovea. By gradually increasing suture tension, the continuous pressure creates and lengthens a vaginal space. This approach requires about 1 week of traction.

In 1992, a laparoscopic modification was developed with results similar to those of the original technique. Fedele and coworkers evaluated the long-term clinical and sexual function outcomes after the laparoscopic Vecchietti procedure in 106 patients with müllerian aplasia. Clinical success was achieved in 104 of 106 patients (98%). Sexual function was successfully achieved in 103 of 106 patients (97%) and was comparable with the control group. They concluded that the laparoscopic Vecchietti procedure was effective and allowed for sexual satisfaction. ^[100]

Peritoneal mobilization

In 1969, Davydov described a laparotomy procedure in which peritoneum from the uterorectal space (pouch of Douglas) was advanced in such manner that a vaginal canal was created. Laparoscopic modifications were later developed and continue to be refined. The modifications use laparoscopy to mobilize the bladder peritoneum, lateral pelvic side walls, and the sigmoid colon. The peritoneum is drawn through the newly created vesicorectal space by using high tension and by approximating it at the introitus. A stent is used for vaginal dilation. Authors report several benefits of this procedure, including minimal scarring and functional vaginas associated with comfortable intercourse. ^[101]

Cervical agenesis is a rare müllerian anomaly with an incidence of 1/80,000 to 1/100,000 females. ^[102]  The uterine cervix is congenitally absent, completely or partially, in this malformation, owing to failure of the paramesonephric ducts to canalize during development. Multiple anatomic structural alterations can arise. Cervical tissue may be present, although it is nonfunctional. An estimated 4.8% of women with cervical agenesis have a functional uterus. Associated vaginal aplasia and renal anomalies may also be present. ^[103]  The anomaly is categorized as cervical agenesis and distal cervical agenesis in the ASRM (2021) müllerian anomalies classification. ^[43]

The usual presentation is an adolescent with primary amenorrhea and cyclic abdominal-pelvic pain, who often exhibits varying degrees of outlet obstructive symptoms, including hematometra and hematocolpos. The uterus and fallopian tubes in severe cases can become distended by menstrual blood, and ovarian torsion can also occur. ^[37]  The differential diagnosis includes high transverse vaginal septum and imperforate hymen. Early, definitive diagnosis is paramount as the condition can be associated with significant morbidity and mortality, depending on the extent of the defect. Ultrasonography is usually the first diagnostic modality conducted. Although MRI is considered the gold standard in diagnosing müllerian duct anomalies, imaging results may not correlate with clinical and intraoperative findings, particularly when the malformation involves the lower uterine segment and atretic cervix. ^{[103, 104]}

Preoperative evaluation

Comprehensive informed consent is warranted. Counseling should include discussion with patients and their families about potential postoperative complications and the extent of the cervical defect, as well as the desired treatment outcome. ^[105]  Risks of the procedure will depend on the surgical approach. For patients who desire uterine preservation and menses, a reconstructive approach may be considered. Postoperative complications include recurrent obstruction at the anastomotic site, additional surgeries, and serious infections. In some cases, hysterectomy may be the preferred approach.

Surgical management

Management of cervical agenesis has been controversial for multifactorial reasons. Various approaches depend upon the anatomic defect and include uterovaginal anastomosis, cervical canalizations by coring and drilling techniques, uterine cavity catheterization, and hysterectomy. ^{[102, 103]}  Indeed, various reports describe reconstruction attempts to create an epithelialized uterovaginal tract for menstruation flow and preserved fertility. Unfortunately, many of the methods met with complications. ^{[102, 105, 106]}

Advances in minimally invasive surgery and robotics have revitalized reconstructive surgery efforts, with varying reports of success. No standard surgical approach has been established, owing to the rarity of the condition and the descriptive nature of historical reports, as well as the absence of carefully designed cohort studies and randomized trials. ^{[103, 107]}

Rock et al reported on their experience with 30 cases of cervical agenesis and dysgenesis, spanning nearly 7 decades. ^[103]  They proposed a protocol for managing congenital cervical anomalies and outlined in their communication the anatomic variations. The intention is for future reports to elucidate the anatomic structure of the cervical anomaly so that comparisons between patient series may be possible. ^[103]

The surgical approach should be individualized in accordance with the respective anatomic defect(s) and should also take into consideration the patient’s desired outcomes. Reconstructive surgery must be performed by highly skilled surgeons who are experienced in complex müllerian reconstruction procedures and who can adapt and modify their approach according to the observed and intraoperative anatomic defect(s). ^{[103, 105, 108]}

Complications and results

Uterovaginal anastomosis is not indicated in all patients with cervical agenesis and cervical dysgenesis. Indeed, the approach is associated with significant complications. Past reports included endometritis, pelvic inflammatory disease, chronic pelvic pain, pelvic endometriosis, bowel and bladder injury, recurrent obstruction, restenosis requiring subsequent surgeries, and even death. Some of these complications may have been mitigated by modern advances and pharmaceuticals. ^{[103, 105]}

The unicornuate uterus is formed when one müllerian duct completely or incompletely fails to elongate while the other develops normally. However, three separate reports describing the coexistence of a unicornuate uterus with ipsilateral ovarian agenesis has led some authorities to consider that, in some cases, the unicornuate uterus may arise as a consequence of agenesis involving all structures derived from one urogenital ridge. ^{[109, 110, 111]}

Unicornuate uterus accounts for approximately 2.4-13% of all müllerian anomalies. ^{[41, 8, 7]} In a retrospective longitudinal review, the incidence of unicornuate uterus was 0.06% for the examined population, which included more than 3000 women of reproductive age who desired conception. ^[112]

This class of uterine structural defects is anatomically diverse. The unicornuate uterus may occur alone, but it is frequently associated with a rudimentary horn. ^{[41, 113, 114]} The AFS classification divides this group into 4 categories based on the presence or absence of a rudimentary horn. The accessory horn can have a uterine cavity with functional endometrium, and, in some cases, a communication may exist with the main endometrial cavity. Associated urologic anomalies are frequent (44%), especially in the presence of an obstructed horn. Associated urological anomalies include ipsilateral renal agenesis (67%), horseshoe kidneys, and ipsilateral pelvic kidney (15%). ^[113]

Noncommunicating accessory horns that have an endometrial cavity are the most common unicornuate subtype and are the most clinically significant. This subtype is associated with increased morbidity and mortality. When the accessory horn becomes obstructed, several complications, such as hematometra, can develop. There is also an increased risk of developing endometriosis, which usually resolves after excision of the horn, provided that an early diagnosis was rendered. ^[115]

Although normal pregnancies can occur, obstetric outcomes are generally poor in this group. Unicornuate uterus is associated with the poorest fetal survival among all müllerian anomalies. ^[46] Cesarean delivery rates are high. Common obstetrical complications include malpresentation, intrauterine growth retardation, and preterm birth. ^{[116, 93]}

A review of compiled data from several studies of uterine anomalies and pregnancy outcomes revealed that the unicornuate uterus had the poorest overall reproductive outcomes of all the uterine anomalies. Problems with reproduction were attributed to abnormal uterine vasculature and diminished myometrial mass of the unicornuate uterus. Analysis of 393 pregnancies revealed the following outcomes for the entire unicornuate class: 170 (43.3%) preterm deliveries, 213 (54.2%) live births, 17 (4.3%) ectopic pregnancies, and 135 (34.4%) spontaneous abortions. About 2% of the pregnancies occurred in the accessory horn. ^[117]

A similar report of 20 studies that included 290 women with surgical or radiographically confirmed unicornuate uterus and a total of 468 pregnancies had comparable outcomes. ^[118] These statistics provide significant insight into obstetrical outcomes for the entire unicornuate group. However, most reports did not provide the specific AFS unicornuate subclass so that, in a given subclass, actual reproductive outcomes cannot be evaluated.

Adverse obstetric complications can also involve the accessory horn and include ectopic pregnancy, missed abortion, and uterine rupture. ^[119] For these reasons, the horn should be excised prior to pregnancy as a preventative measure. Pregnancy in a noncommunicating horn is uncommon and is thought to be due to transperitoneal sperm migration into the fallopian tube of the rudimentary horn. Most obstetric complications occur in the first 20 weeks and can result in abortion, uterine rupture, or maternal death (0.5%). ^{[120, 121, 122, 114]}

Diagnosis of unicornuate uterus

Women with noncommunicating, functioning rudimentary horns may present with pelvic pain usually secondary to hematometra or endometriosis. Often the first step is the 2-dimensional ultrasound or 3-dimentional ultrsound is useful. Although HSG is useful in diagnosing a unicornuate uterus, it does not help in detecting a noncommunicating horn. MRI is considered the gold standard as it reliably helps in making this distinction and should be one of the first diagnostic tools used in evaluating such patients. MRI reveals a slender, laterally deviated banana-shaped uterus.

Only one fallopian tube is identified. The zonal anatomy is normal, though the uterine volume is reduced. The accessory horn can appear solid because it is not opacified when endometrium is absent. It is located adjacent to the main uterine cavity. It can also be observed as a soft tissue mass. When endometrium is present, a small cavity can be detected; this may or may not communicate with the main endometrial cavity. ^{[69, 68, 70, 71, 123]}

High-resolution ultrasonography is useful for identifying rudimentary horns and is more reliable than laparoscopy for determining whether the horn is communicating.

Laparoscopy is rarely indicated in the workup of an obstructed, noncommunicating horn. ^[124]

Additional studies should include IVP or renal ultrasonography to help evaluate for ipsilateral renal agenesis, horseshoe kidney, and ipsilateral pelvic kidney. ^[125]

Preoperative evaluation

The unicornuate uterus is uncommon, and this is reflected in the scarcity of data in the literature regarding surgical strategies, especially for treatment of the various subtypes. Specific surgical management plans have not significantly advanced. Women with unicornuate uterus are not generally considered for reconstruction metroplasty. ^{[5, 115, 126]} The indication for surgery is the presence of endometrium in the noncommunicating accessory horn, owing to obstructive complications. Laparoscopic hemihysterectomy of the rudimentary horn is the treatment of choice. ^{[121, 122]} Surgical treatment is not indicated when the rudimentary horn lacks an endometrium. ^[127]

Surgical technique for rudimentary horn excision

Excision of an accessory horn is accomplished by means of laparoscopic hemihysterectomy. The bladder is emptied through the insertion of a Foley catheter. The standard 3-part set-up is used, including 2 lateral ports and a medial port. A tenaculum is used for uterine mobilization. The reproductive organs are examined for any other abnormalities. Anatomic variations of horn attachment to the unicornuate uterus exist. A fibromuscular band often connects the 2 horns. In this setting, the uterine artery courses inferior to the band and can be easily coagulated. The band is desiccated by using bipolar cautery and transected. On occasion, the horn can be firmly attached to the unicornuate uterus. In this setting, the uterine artery courses inferior to the horn and lateral to the unicornuate uterus.

The pedicle of the rudimentary horn is coagulated using bipolar coagulation. Scissor division is performed close to the desiccation line to ensure that the compressed pedicle remains intact. The mesosalpinx is cauterized and cut, allowing removal of the fallopian tube. The peritoneum of the vesicouterine space can be grasped and elevated with forceps, while the vesicouterine space is dissected by using scissors. Aqua dissection may be used to separate the leaves of the broad ligament. The vesicouterine space is distended, and the bladder attachments are coagulated and cut. The tube and rudimentary horn are removed, leaving the functional ovary.

Dissection is more complicated when the horns are not externally separated. The myometrium is resected at the junction of the horns by using bipolar coagulation followed by mechanical or laser cutting. After the myometrium resection is complete, the rudimentary horn can be removed. Morcellation is often required when the rudimentary horn is large. ^{[121, 122]}

In the event a pregnancy occurs in a noncommunicating horn, laparoscopic excision of the pregnant horn is advocated. Excision of the pregnant horn is similar to that performed for nonpregnant horns, though one must be mindful of increased pedicle vascularity. Successful pregnancy in the major horn has been reported after laparoscopic removal of accessory horn. ^[128] Cutner and coworkers reported their experience with two pregnancies in noncommunicating horns. ^[129] The pregnancies were medically treated with methotrexate before horn excision. The authors concluded that this approach allowed the excision to be delayed to a safe and less invasive time.

Endometrial ablation of accessory horn endometrium through a hysteroscopic approach is reported for treatment of symptomatic hematometra. At 3-year follow-up, patients were free of symptoms. Neither hematometra nor dysmenorrhea had recurred. ^[130] Hysteroscopic drainage of a hematometra in a noncommunicating accessory horn by using electrocautery to create a communication between the horns has been also described. At 1 month follow-up a single uterine cavity was identified and there was complete symptom relief. ^[131] Additional studies are needed before these treatment modalities are widely accepted.

Postoperative management

In most cases, the patient can be discharged on the day of surgery. No special precautions are needed.

Complications and results

Associated complications include those complications associated with laparoscopy for gynecologic surgery.

Postsurgical obstetric outcomes have been impressive, especially for this group. Donnez and Nisolle reported a study of 14 women with unicornuate uterus who underwent laparoscopic removal of a rudimentary horn. Six of 8 women who attempted pregnancy became pregnant. All but 1 had subsequent vaginal delivery after 36 weeks. One patient underwent cesarean delivery because of fetal indications. ^{[121, 122]}

Didelphys uterus arises when midline fusion of the müllerian ducts is arrested, either completely or incompletely. Approximately 11% of uterine malformations are didelphys uterus. ^[10] The complete form is characterized by 2 hemiuteri, 2 endocervical canals with cervices fused at the lower uterine segment. Each hemiuteri is associated with one fallopian tube. Ovarian malposition may also be present. ^[132] The vagina may be single or double, with duplication a frequent component. The double vagina manifests as a longitudinal (horizontal) septum that extends either completely (complete septum) or partially (partial septum) from the cervices to the introitus. A complete longitudinal vaginal septum occurs in 75% of these anomalies, although vaginal septa can also coexist with other müllerian duct anomalies. ^{[80, 113, 119]} In some cases obstruction can be due to transverse vaginal septa.

Patients with a uterine didelphys are usually asymptomatic, unless an obstruction is present. In such cases, hematometrocolpos, hematometra, and hematosalpinx may develop.

Renal agenesis most commonly occurs in association with uterine didelphys than with any other type of müllerian anomaly. The reported incidence of renal anomalies in this group is 20%. ^[5]  In this setting, there is the rare although well-established congenital Herlyn-Werner-Wunderlich syndrome. It is characterized by anomalies of both the müllerian and wolffian ducts, consisting of the following triad: uterus didelphys, obstructed hemivagina and ipsilateral renal agenesis. ^{[133, 134]} A number of case reports regarding this variant were published between 2000 and 2004. ^{[135, 136, 137, 138, 139, 140, 141]} The earlier publications reflected the burgeoning use of MRI in the diagnostic evaluation. To date, only a few hundred cases, along with their case managements, have been published.

Renal agenesis is thought to be due to developmental arrest in one wolffian duct that in turn affects induction of nephrogenesis and positioning of the ipsilateral müllerian ducts. The malpositioned müllerian duct is incapable of successful fusion, and 2 hemiuteri develop. Familial occurrences are reported, though definitive genetic associations have not been identified. ^[5]

In single case studies, didelphys uterus is reported to occur in association with other anomalies. Some coexisting anomalies include the following: bladder exstrophy with or without vaginal hypoplasia; congenital vesicovaginal fistula with hypoplastic kidney; and cervical agenesis. ^{[142, 143, 144, 145]}

The complex malformation of uterine didelphys with superior vagina duplication and inferior vaginal agenesis has been reported in a case series involving 3 young adolescents. Each patient underwent extensive diagnostic and preoperative evaluations, which accurately defined the anomaly. Surgical correction involved laparoscopic bilateral pull-through vaginoplasties, some in stages, with each receiving interval hormone suppression. ^[146] This anomaly illustrates some of the complexities that can accompany müllerian anomalies and how crucial accurate diagnostic and preoperative evaluations are to planning the proper surgery and, importantly, successful outcomes.

An unusual capability of didelphys uterus is that, in many cases, intercourse is often possible in both vaginas. Moreover, simultaneous pregnancies in each uterus can occur, albeit rarely. The twins are always dizygotic. Some experts consider each pregnancy a separate entity. This theory is supported by reports in which the second twin was delivered after a long interval, ranging from 3 hours to 5 days to 8 weeks, after delivery of the first twin. ^{[147, 148, 149]} Lactation is reported to occur after the birth of the second twin. ^[148]

Management of delivery is controversial. Some authorities believe that vaginal delivery can be safely achieved, whereas others advocate cesarean delivery. In an exceptional case, 1 twin was delivered by means of cesarean delivery at 25 weeks' gestation, and the second twin was delivered by means of spontaneous vaginal delivery at 35 weeks. Both twins were eventually discharged home without complications. ^[149] Because twin didelphys pregnancies are rare, data in the literature about obstetric outcomes are scarce. Reported complications include unilateral placental abruption and unilateral premature labor. ^{[150, 149]}

The low incidence of uterine didelphys is reflected in the literature by the paucity of data regarding reproductive performance. Compiled data from 2 studies that included didelphys uterus anomaly revealed the following outcomes for 86 pregnancies: 21 (24.4%) preterm deliveries; 59 (68.6%) live births; 2 (2.3%) ectopics, and 18 (20.9%) spontaneous abortions. ^[117] The poor reproductive outcomes are thought to be due to diminished uterine volumes and decreased perfusion of each hemiuteri.

Malignancies can occur in müllerian anomalies, and one must be mindful of this possibility when treating these women. Cervical cancer as well as endometrial adenocarcinoma have been reported to rarely occur. An exceptionally rare occurrence in uterine didelphys is the development of unilateral endometrial adenocarcinoma. ^{[151, 152]}

Diagnosis of uterine didelphys

Nonobstructive uterus didelphys is usually asymptomatic until menarche. The most frequent complaint is failure of tampons to obstruct menstrual flow. The diagnosis is often rendered during the initial pelvic examination, when 2 cervices are identified. A history of second-trimester spontaneous abortion is often a clue to this condition.

In hemivaginal obstruction, the clinical presentations are variable and depend on the degree of obstruction and whether the obstruction has an opening. The most common presenting symptoms are onset of dysmenorrhea within the first years following menarche and progressive pelvic pain. A unilateral pelvic mass is detected on examination with the right affected nearly twice as frequently as the left. Presenting symptoms of marked rectal pain and constipation, secondary to hematocolpos impingement, have been reported in 1 case. ^[137]

Diagnostic modalities are similar to those used for unicornuate uterus. Two and/or 3-dimensional ultrasound are often the first diagnostic methods used. Workup should include HSG, MRI, and IVP to confirm or exclude associated urinary tract anomalies. MRI reveals 2 widely separated uterine horns, and 2 cervices are typically identified. The intercornual angle is >60°. The zonal anatomy is preserved within each hemiuterus. ^[123]  A TVS is usually observed. ^[70] Obstructions are represented by variable dilation of the vaginal component and diminished endometrial dilation. ^[153] Ultrasonography may be a valuable adjunct. ^{[154, 155, 156, 68]}

Preoperative evaluation

The obstructed unilateral vagina is an indication for resection of the vaginal septum. Surgery is necessary to preserve reproductive capacity and to prevent impairment of the uterus and tubes. Unless readily removed after diagnosis, retrograde menstruation continues and hematometra and hematosalpinx may develop. Endometriosis and pelvic adhesions also may occur. ^[157] In the setting of pregnancy and an obstructed vagina, septum resection may be indicated. Sonography findings help determine if the pregnancy is ipsilateral or contralateral to the obstructed side.

When the vagina is not obstructed, indications for surgical correction are limited, with dyspareunia the most notable. Selected patients with a long history of recurrent spontaneous abortions or preterm births may benefit from metroplasty, though this approach requires confirmation by additional studies before it is widely recommended. Indeed, some authorities contend that unification surgery for the didelphys uterus has few indications and the results may be disappointing. Cervical unification is technically difficult and can result in cervical incompetence or stenosis. ^[46]

The management of a nonobstructed longitudinal septum in pregnancy is not clear. Some authors advocate excision, whereas others recommend leaving it undisturbed unless it becomes obstructed during labor. ^[113]

Surgical techniques

Surgical techniques are as follows:

• Uterine didelphys with obstructed unilateral vagina

  • Full excision and marsupialization of the vaginal septum is the preferred approach and is performed as a single procedure. After the septum has been excised, laparoscopy can be performed for potential treatment of associated endometriosis, adhesions, or both. ^[158]

  • Excision of an obstructed vaginal septum during pregnancy requires leaving a generous pedicle to help minimize potential bleeding should the vaginal mucosa retract. ^[113]

  • Hemihysterectomy with or without salpingo-oophorectomy is rarely indicated and should be avoided to provide the best opportunity for a successful reproductive outcome.

• Uterus didelphys, nonobstructed

  • As previously stated, indications for septum resection in the nonobstructed didelphys uterus are limited. These patients are not candidates for surgical unification. Fortunately, few fertility-associated problems occur in this group. If the woman carries a pregnancy to term, obstetric complications are usually minimal.

  • The decision to perform metroplasty should be individualized, and only selected patients may benefit from surgical reconstruction. Most reports of metroplasty in this setting are anecdotal and the apparent benefits of surgery are not clear.

  • This stated, the recommended procedure is the Strassmann metroplasty. ^[4] This method unifies the uterine cavities at the fundus, while the cervices are left intact. This procedure is detailed further in Surgical techniques for bicornuate uterus below.

Postoperative management

Vaginal adenosis is a risk after the septum is removed. Definitive guidelines that monitor for this condition have not been established, though some experts recommend serial Pap smears and colposcopy. ^[133]

Complications and results

After the obstructed vaginal septum is surgically removed, the affected uterus and tube should regain their normal appearance and function. Pyocolpos has not been reported to occur. ^[158] Hematometra and hematosalpinx can recur if the septum is incompletely excised. ^[134]

Uterus didelphys with obstructed unilateral vagina can be diagnosed early and accurately. It is easily corrected, with diminished long-term morbidity and preservation of reproductive function in most of cases. Stassart and associates reported favorable obstetrical outcomes in 10 intrauterine pregnancies. Five resulted in term delivery, 4 resulted in preterm delivery, and 1 resulted in early spontaneous abortion. ^[158]

The bicornuate uterus is formed when the müllerian ducts incompletely fuse at the level of the uterine fundus. In this anomaly, the lower uterus and cervix are completely fused, resulting in 2 separate but communicating endometrial cavities, a single-chamber cervix and vagina. A muscular intrauterine septum is also present, and this defect corresponds externally to an indentation or groove at the fundus. The depth of the groove and length of the uterine septum depend in the adult uterus on the length of the incompletely fused müllerian ducts in the fetus. ^[126]

Subclassification into complete or partial categories depends on septum length. Complete uterine septa that extend either to the internal or external os are known as bicornuate unicollis uterus and bicornuate bicollis uterus, respectively. When the septum is confined to the fundal region, it is considered a partial bicornuate uterus.

Bicornuate uterus is considered an incidental finding. The uterine bicornuate has been identified as an infrequent component of a mild, nonlethal variant of the urorectal septum malformation. ^[159]

Women with this anomaly usually have few reproductive-associated problems. The condition usually remains undiagnosed until cesarean delivery or other procedures reveal its existence. In large study of infertile women, the incidence of bicornuate uterus was not significantly different from that of the fertile control group, suggesting that these patients usually have no difficulty becoming pregnant. ^[112] Approximately 60% of patients can expect to deliver a viable infant, though they may present with late abortion or premature labor. ^[160]

Obstetric outcomes may be related to length of the muscular septum, ie, whether the bicornuate uterus is partial or complete. In 1 report, women with a partial bicornuate uterus had a spontaneous abortion rate of 28%, and the preterm delivery rate was 20%. This finding contrasts with the higher reported incidences of spontaneous abortions (66%) and preterm deliveries in women with complete bicornuate uterus. ^[125] In rare cases, a twin pregnancy can occur in a single horn of the bicornuate uterus. In one such case report, the pregnancy terminated at 22 weeks by spontaneous abortion. ^[161]

Literature examining reproductive outcomes of bicornuate uterus is sparse. In the comprehensive review of reproductive outcomes for müllerian anomalies by Lin et al, only 1 observational study was cited. From that study, the following outcomes were reported for 56 bicornuate pregnancies: 14 (25%) preterm deliveries, 35 (63%) live births, 0 (0%) ectopics, and 14 (25%) spontaneous abortions. The authors did not subclassify the bicornuate uteri; therefore, it is not possible to correlate these outcomes with a specific bicornuate subgroup. ^[117]

Müllerian anomalies appear to suffer from the same pathologic conditions affecting normal uteri, including cancer. A high-grade endometrial carcinoma developed in one horn of the bicornuate uterus after the patient received tamoxifen therapy for breast cancer. ^[162]

Diagnosis of bicornuate uterus

The most important step is to distinguish the bicornuate uterus from the septate uterus. An accurate, definitive diagnosis must be rendered because their treatment strategies and reproductive outcomes markedly differ. Indeed, uterine bicornuate does not usually require surgery and is associated with minimal reproductive problems, while the septate uterus can be surgically corrected and has a high association with reproductive failure.

The 2021 ASRM müllerian anomalies classification defines the bicornuate uterus as having an external fundal indentation of  >1.0 cm in length and remains unchanged from the 2016 ASRM practice guidelines. ^[43] Evaluation of bicornuate uterus should begin with ultrasonography during the luteal phase of the menstrual cycle, when the endometrial echo complex is better identified. Sonographic studies based on the intercornual angle do not help in accurately distinguishing a septate uterus from a bicornuate uterus.

Further evaluation by MRI can help make this distinction. On MRI, 2 uterine bodies and a single cervix characterize the bicornuate uterus. The intercornual distance is increased to >105°. The myometrial tissue that separates the 2 horns has a signal intensity identical to that of the myometrium. ^{[123, 163]} The external contour is outward concave, which contrasts with the outward convexity of normal and septate uteri. ^[71] MRI findings of the septate uterus reveal a persistent longitudinal septum partially dividing the uterine cavity with intercornual angle ≤ 75°. The gray area is when the intercornual angle is >75° but < 105°. In this condition, other diagnostic modalities, such as laparoscopy, must be considered.

Laparoscopic examination of the fundal contour can readily distinguish the bicornuate uterus from the septate uterus. The major difference between the two is the anatomic appearance of the external uterine fundus. The bicornuate uterus has 2 horns, whereas the appearance of external fundus of the septate uterus is normal.

The cornerstone of the diagnostic evaluation for most uterine structural anomalies is HSG; however, HSG cannot reliably distinguish bicornuate from septate uteri because their uterine cavity images are similar (ie, double uterus). ^{[154, 155, 68]} The reported accuracy of HSG in differentiating bicornuate from septate is 55%. ^[164] In a retrospective analysis of medical records from 36 women with bicornuate uterus diagnosed with HSG, 34 (94%) were subsequently identified as having septate uterus after combined laparoscopy, and hysteroscopy were performed. ^[165]

Preoperative evaluation

Bicornuate uterus seldom requires surgical reconstruction. ^[67] The benefits of metroplasty have never been studied in a prospective trial with data from most reports obtained from observational studies. ^[126] Metroplasty should be reserved for women who have experienced recurrent spontaneous abortions, midtrimester loss, premature birth, and in whom no other etiologic factor has been identified. ^{[127, 126]}

Surgical techniques for bicornuate uterus

Although a number of metroplasty procedures are available, the Strassmann procedure is the surgical treatment of choice for unifying the bicornuate and didelphys uteri. Transcervical lysis used in other anomalies is contraindicated in this setting because it can result in uterine perforation. ^[46] The Strassmann procedure removes the septum by wedge resection with subsequent unification of the 2 cavities. The modified Strassmann procedure involves the approach described next.

Prophylactic antibiotics are administered preoperatively, and the usual reproductive techniques to minimize adhesions are observed throughout the procedure.

A Pfannenstiel incision is made, and the pelvic organs, vessels, and ureters are examined. The rectovesical ligament is frequently present and should be completely excised prior to performing the wedge resection. It is identified anteriorly by its attachment to the bladder and courses between both uterine horns, where it is also attached. It continues posteriorly in the cul-de-sac to terminate at its attachment to the anterior surface of the sigmoid and rectum.

• Wedge resection of the uterine horns

  • Tourniquets are applied similar to the modified Jones procedure to promote hemostasis. A wedge-shaped incision, deep enough to enter the endometrial cavity, is made on the medial aspect of each uterine horn.

  • The incision extends from the superior aspect of each horn, near the interstitial region of the fallopian tubes, to the inferior aspect of the uterus.

  • The goal is to achieve a single endocervical canal. If 2 cervices are present, their unification is not recommended.

• Apposition of the myometrium

  • After resecting the wedge, the myometrial edges naturally evert. Apposition of the opposing myometrium is achieved using interrupted vertical figure-8 sutures along the posterior and anterior uterine walls.

  • When suturing the fundal region, one must be mindful in placing the sutures too close to the tubal ostia. The opposing myometrium merges as the sutures are tied forming a united uterine cavity.

  • The final layer is closed using continuous subserosal sutures, without exposing any suture material to the peritoneal cavity.

  • After tourniquet removal, broad ligament incisions are repaired using very fine sutures. Transvaginal dilatation of the cervix is performed, assuring proper endometrial cavity drainage. ^{[4, 46]}

Postoperative management

Prophylactic antibiotics are continued postoperatively. The recommended hospital stay is 2-3 days. The patient must use barrier contraception for 3 months, after which conception can be attempted. ^[46]

Complications and results

Complications include those found in any other gynecologic surgery, such as bleeding, infection, and injury to the bowel and bladder.

A considerable number of women with bicornuate uterus who undergo metroplasty can expect to become pregnant and deliver a viable infant. Transabdominal metroplasty can substantially improve the reproductive performance of women with bicornuate uterus who had recurrent spontaneous abortions or premature deliveries before surgery. ^[127] Strassmann reported that, of 263 pregnancies in women who had undergone metroplasty, 86% had viable births. ^[4] Of importance, most of these infants were delivered vaginally, with no reports of uterine rupture during pregnancy or delivery. Despite these findings, some experts recommend elective cesarean delivery. A retrospective analysis of 22 women with bicornuate uterus who underwent Strassmann metroplasty revealed that 19 (86%) had viable births. These pregnancies went to term without clinically significant complications, and all women underwent cesarean deliveries. ^[166]

Septate uterus is the most common structural abnormality of all müllerian duct defects. It results from incomplete resorption of the medial septum after complete fusion of the müllerian ducts has occurred. The septum, located in the midline fundal region, is composed of poorly vascularized fibromuscular tissue. ^[9] Numerous septal variations exist. The complete septum extends from the fundal area to the internal os and divides the endometrial cavity into 2 components. This anomaly is often associated with a longitudinal vaginal septum. ^[125] The partial septum does not extend to the os. Some septa may be segmental, permitting partial communication between the endometrial cavities. ^[124]

A variant septate anomaly characterized by the triad of complete septate uterus, duplicated cervix, and vaginal septum is recognized and may be more common than previously reported. ^{[167, 168, 169, 116, 25, 26, 170, 171]} The most common presenting symptoms are dyspareunia, dysmenorrhea, and primary or secondary infertility. ^[171] Pregnancy loss and obstetrical complications also occur in this anomaly.

Because of the presence of 2 cervices, this entity should be distinguished from the didelphys uterus because each has different reproductive outcomes and treatment strategies. In general, a complete septum would be removed hysteroscopically, whereas no surgical intervention would be recommended for the uterine didelphys. On laparoscopy, the uterine fundus has a normal, smooth contour. ^[171] This anomaly is intriguing because its very existence challenges our widely accepted theories on müllerian development and indicates that müllerian fusion may occur bidirectionally.

A rare variant septate uterus is the Robert uterus. ^[172] This entity is characterized by a complete septum and noncommunicating hemiuteri with a blind horn. Patients usually present with unilateral hematometra and dysmenorrhea. A 26-week pregnancy in a Robert uterus was reported; it was unfortunately terminated by fetal demise. ^[173]

Fertility does not appear to be substantially compromised in patients with a septate uterus. Yet, this anomaly is associated with the poorest reproductive outcomes of all the müllerian duct anomalies, as it is associated with both first and second trimester miscarriages, yet the treatment can successfully be achieved.  A comprehensive review of combined data from several studies that addressed reproductive outcomes of the septate uterus revealed the following outcomes: 146 (10%) preterm deliveries (n = 1459), 90 (58.1%) live births (n = 155), 3 (1.9%) ectopics (n = 155), and 1105 (75.7%) spontaneous abortions (n = 1459). ^[117] Despite these findings, this condition is not always associated with an unfavorable obstetric outcome, and its presence alone is not an indication for surgery.

Diagnosis of the septate uterus

The 2021 ASRM müllerian anomalies classification modified the diagnostic criteria from the 2016 ASRM practice guidelines. ^{[43, 174]}  The septate uterus is defined as having a length of >1 cm as measured from the bicornual line, with the leading septal edge having an angle of < 90º.

In general, a combination of diagnostic modalities is needed to arrive at a definitive diagnosis. The most frequently used approaches are HSG, hysteroscopy, and laparoscopy. Ultrasonography and MRI are also useful. HSG reveals a 2-chambered uterus. The length and thickness of the septum can be assessed, with concomitant tubal patency also assessed. However, neither HSG nor hysteroscopy help in distinguishing a septate uterus from a bicornuate uterus. ^{[175, 165]} Laparoscopy aimed at determining normal fundal contour is best for distinguishing these entities.

Transvaginal ultrasonography is a useful aid in diagnosing septate uterus. One study demonstrating a sensitivity of 100% and a specificity of 80%. ^[155] Results from combining transvaginal ultrasonography with color Doppler imaging resulted in 95% sensitivity and 99.3% specificity for septate diagnoses. ^[176] In a prospective study of 40 women with history of recurrent reproductive failure, accuracy of physician interpretation of 3-dimensional sonograms was 92% for the diagnosis of septate uterus. ^[177] Three dimensional (3-D) ultrasonography is becoming more widely available outside major medical centers. In a prospective cross-sectional observational study involving 69 infertile adult females, the diagnostic accuracy of identifying uterine cavity defects by 3-D transvaginal ultrasound was compared with the gold standard approach, hysteroscopy. The authors concluded that 3-D transvaginal ultrasound had high diagnostic accuracy (84.1%). The limitation of the study was that only one uterine malformation, a septate uterus, was diagnosed. That stated, the study is an indicator that this modality may successfully detect this anomaly. ^[178]

MRI provides excellent tissue characterization and helps in reliably differentiating a septate uterus from a bicornuate uterus. ^[179] MRI reveals low signal intensity for the septum, a normal fundal contour with outward fundal convexity. ^[71]

Preoperative evaluation

The decision to perform surgical correction of the septum should be based on poor reproductive performance rather than the presence of a septate uterus. ^[125] Candidates for surgery include women who had recurrent spontaneous abortions, a single second-trimester loss, or history of preterm delivery. ^{[15, 179]}

Some authorities recommend preoperative pharmacologic therapies, such as progestins, danazol, or gonadotropin-releasing hormone agonists, to reduce the thickness of the endometrium and to aid visualization. ^{[175, 180]} Others schedule surgery during the early follicular phase of the menstrual cycle, when the endometrium is already minimized.

Although urinary tract anomalies are not commonly associated with septate uterus, renal ultrasonography and/or IVP should be performed to help exclude or detect any concomitant anomalies.

Surgical techniques

The surgical procedure of choice is hysteroscopic metroplasty with concurrent laparoscopy. ^{[181, 46, 180]} Laparoscopy helps reduce the risk of uterine perforation during septal incision. ^[182] As an alternative, transcervical ultrasonographic guidance has been reported as an adjuvant to hysteroscopic metroplasty. ^[183]

Management strategies for women having the variant complete septate uterus with duplicated cervix and vaginal septum vary. In the past, transection of the cervical septum segment has been controversial and associated with increased surgical complications and risk of cervical incompetence. In an observational study of 16 women with this variant who experienced either pregnancy loss (9 patients) or dyspareunia (7 patients), both hysteroscopic metroplasty (11 patients) and transabdominal-modified Tomkins metroplasty (5 patients) were used to correct the uterine septal abnormality. None of the patients underwent incision of the cervical segment of the septum and postoperative reproductive outcomes were impressive. ^[170]

Similarly, in a randomized study involving 28 females with this variant anomaly, 15 women underwent cervical septum incision, while in 13, the cervical septum was preserved. No intraoperative or postoperative complications were recorded, and the authors reported that the procedure actually rendered the surgery easier. Both groups achieved equivalent favorable reproductive outcomes. While occasional patients from each group required cervical cerclages, these differences were not considered significant. ^[184]

• Laparoscopy

  • The double-puncture technique is used, with a probe passed through the inferior incision. The probe is used to keep the uterine fundus in view.

  • Examination of the uterus can help verify the concave external shape of the septate uterus, further distinguishing it from a bicornuate uterus. It can also help in detecting unexpected pelvic disease.

• Hysteroscopy

  • The laparoscope is placed, and hysteroscopy commences. The cervix is dilated to 6 mm, and the hysteroscope is inserted to the level of the external os. It is advanced into the uterine cavity under direct vision. Distention media depends on the instruments used to dissect the septum.

  • Operative hysteroscopic metroplasty can be performed by using microscissors, electrosurgery, or a laser. The following approach uses microscissors.

    • Flexible microscissors are passed through the operating channel of the hysteroscope. The inferior aspect of the septum is visualized, and the septum is progressively dissected until a cavity with a normal-appearing contour is achieved. The laparoscopist observes the serosal surface of the uterus to detect any tissue blanching and localized light emanating from the hysteroscope. When this occurs, the procedure is too close to the surface.

    • When the septum is 3 cm or less at the fundus, the incision can be carried cephalad from the most inferior aspect of the septum and directed laterally as the most superior aspect of the uterus is approached. When the septum is greater than 3 cm at the fundus, the incision is started at the most inferior portion of the septum. The scissors are directed superiorly along 1 lateral margin of the septum until that margin is incised up to 0.5 cm from the junction of the septum and normal myometrium. The opposite lateral margin is similarly incised.

    • This process is repeated with each new lateral aspect incised alternatively until the original V -shaped septum is reconfigured into a short, broad notch between the tubal ostia. The notch is incised by starting near the tubal ostia and progressing to the opposite ostia. When the junction between the septum and myometrium is incised, minimal bleeding can occur. Otherwise, the procedure has little blood loss because the septum is poorly vascularized.

    • In the septate variant with duplicated cervix, the cervical septum is incised at the proximal aspect using Metzenbaum scissors, laser, or needle electrode followed by uterine corporal incision as described above. ^[184]

  • Dissection of the septum is complete when the hysteroscope can be moved freely from 1 tubal ostium to the other without obstruction, the tubal ostia are visualized simultaneously, and bleeding occurs from small vessels at the fundal myometrium. ^{[185, 182, 181, 186, 180, 170, 184]}

Postoperative management

Postoperative placement of an intrauterine device for a month is controversial. ^{[187, 188]} Some think that it may prevent intrauterine adhesion formation, whereas most experts maintain that this procedure is unnecessary and may provoke local inflammation with subsequent synechiae. ^{[189, 46]} At present, experts are not unanimous about this practice.

Conjugated estrogens 1.25 mg/d for 25 days and progesterone 10 mg/d added on days 21-25 are frequently prescribed after surgery to assist with epithelialization. At present, no consensus has been reached regarding this practice. Some experts believe that hormonal therapy has not been proven necessary and can often be withheld. ^[126] Indeed, results from Dabirashrafi and colleagues' randomized study indicated that estrogen offered no apparent benefit after hysteroscopic metroplasty. ^[190]

Perioperative prophylactic antibiotics are recommended particularly if the patient has a history of pelvic inflammatory disease. No convincing evidence indicates benefit outside of this subgroup.

One-month postoperative follow-up examination is recommended. Either hysteroscopy or HSG can be performed to assess the status of the uterine cavity. HSG is useful for helping detect uterine perforations that may have resulted from hysteroscopy. ^[191] Ultrasonography can also be performed. Experts who advocate this modality conclude that ultrasonographic examination improves resolution of the uterine cavity when it is performed in the secretory phase of the first menstrual cycle after surgery. ^[181] When findings on postoperative examination are normal, pregnancy can be attempted.

Complications and results

Litta and coworkers reported no serious complications in their study of 36 women with uterine septa who underwent hysteroscopic metroplasty; all patients were discharged within 6 hours of their surgery. Correspondingly, no complications were recorded in the variant group that also underwent the same procedure as well as incision of the cervical septum. ^[184] Uterine perforation may occur; however, simultaneous laparoscopy reduces the risk of perforation and can provide early identification if complications develop.

The cervix can be lacerated during instrumentation. Postoperative hemorrhage is reported. In 1 study, clinically significant bleeding occurred in 3% of 91. ^[188] Most investigators report minimal blood loss during this procedure. ^[192] Uterine rupture during a subsequent pregnancy is reported and represents a potential complication. ^[193]

Residual septa are reported to persist. In a study of 68 women who underwent hysteroscopic metroplasty for septate uterus, 44.1% had a residual septum despite the apparent success of the procedure. The authors concluded that, when the residual septum measured less than 1 cm, no adverse effects occurred in reproductive outcomes, and repeat operation was not indicated. ^[186]

Reproductive performance appears to be substantially improved after surgery. To our knowledge, no randomized controlled studies have been conducted to analyze reproductive outcomes in these patients, and the data from most reports is observational. One group reported a reduction in the rate of spontaneous abortions from 86% to 12% in 115 women. ^[192] Another study revealed an 86% delivery rate. ^[194] Data from an early study previously demonstrated these findings. ^[195]

In a retrospective review, Hickok reports his 7-year experience using hysteroscopic metroplasty. The study included 40 women with a high incidence of pregnancy loss (77%) and a low incidence of uncomplicated deliveries (7%) before surgical intervention. After surgery, 21 patients had a total of 22 pregnancies, and the miscarriage rate was 18%. The rate of uncomplicated deliveries was 77.3%. ^[196] In an earlier retrospective study, significantly diminished miscarriage rates (from 80% to 17%) and increased rates of viable births (from 18% to 91%) were achieved after hysteroscopic uterine septum resection. ^[197] Similar results were reported in other observational studies. ^[180]

Hysteroscopic metroplasty with concurrent laparoscopy is the treatment of choice for symptomatic septate uterus. This approach is a safe and effective method of achieving normal or near-normal uterine architecture and is superior to the transabdominal approach. The procedure is significantly less morbid than other methods, it is cost-effective, and it can be performed in an outpatient setting. The risk of pelvic adhesions is limited, and recovery is rapid, with no prolonged postoperative delay in conception. Moreover, it allows for vaginal delivery, obviating subsequent cesarean delivery, as was recommended after the transabdominal approach.

Arcuate uterus

The arcuate uterus results from near-complete resorption of the uterovaginal septum. It is characterized by a small intrauterine indentation shorter than 1 cm and located in the fundal region. It is the most commonly observed uterine anomaly detected by HSG. ^{[198, 13]}

Classification of this anomaly has been problematic. In the classification system of Buttram and Gibbons, it was considered a mild form of bicornuate uterus. ^[41]  In the AFS classification, a separate class was created for this anomaly on the basis of its external unification, which distinguishes it from the septate uterus. Both classification systems speculate whether the arcuate uterus is a normal variant. Compared with other müllerian malformations, arcuate uterus is clinically benign despite an infrequent association with adverse obstetric outcomes, and may not affect reproductive outcomes. ^{[199, 117]}

The 2021 ASRM müllerian anomalies classification defines the arcuate uterus as having an indentation length of ≥1.0 cm, when compared with the normal uterus, which has no indentation. ^[43]

Diagnosis and management of arcuate uterus

The new diagnostic criteria of the arcuate uterus notwithstanding, the literature regarding the diagnosis, management, and reproductive outcomes for arcuate uterus remains limited and conflicting. HSG reveals a single uterine cavity with a saddle-shaped fundal indentation. MRI findings show convex or flat external uterine contour. The indentation is broad and smooth. The signal intensity is myometrial in composition. A subtle associated indentation in the course of the arcuate vessels is sometimes detected, suggesting aberrant vascularity within the fundal myometrium. ^{[198, 13, 153]}  Normal zonal anatomy is evident. Renal ultrasound and IVP may be performed to help exclude any associated urinary tract anomalies; however, these studies are not part of a standard evaluation. Arcuate uterus is usually managed similarly to septate uterus, and only selected patients who fulfill poor reproductive performance criteria are recommended for surgical correction.

Combined data from various studies that included reproductive outcomes for the arcuate uterus were comprehensively reviewed in 1 report. No uniformity was observed with respect to data included for live birth rates, delivery rates, and ectopic pregnancy rates, rendering interpretation of the following reproductive outcome results difficult: 283 pregnancies: 10 (5.1%) of 195 preterm deliveries, 129 (66.2%) of 195 live births, 7 (3.6%) of 195 ectopics, and 57 (20.1%) of 283 spontaneous abortions. ^[117]

The longitudinal vaginal septum most commonly occurs in association with other congenital uterine anomalies. Indeed, in a large retrospective study that included 202 cases, the researchers reported an 87.8% association with uterine defects, particularly in the complete or partial high septum (99.4%). ^[200]  Accordingly, the septum has been previously addressed in the didelphys, bicornuate, and septate uterus sections, as well as cervical duplications. A report on the developmental origin in vaginal epithelium in a mouse model attributed incomplete fusion of 2 müllerian ducts to the developmental defect giving rise to the complete longitudinal septum. ^[36]

The 2021 ASRM müllerian anomalies classification has stratified the malformation into the following categories ^[43] :

• Longitudinal vaginal septum of variable length
• Longitudinal vaginal septum of variable length associated with uterus didelphys
• Obstructed hemivagina (right or left) associated with uterus didelphys
• Longitudinal vaginal septum of variable length associated with complete septate uterus and duplicated uterine cervix
• Obstructed hemivagina (right or left) associated with complete septate uterus and duplicated uterine cervix

Obstetrical concerns are mainly related to a uterine malformation, but a thick septum may be responsible for dystocia. ^[200]

The transverse vaginal septum (TVS) is formed when the tissue between the vaginal plate and the caudal aspect of the fused müllerian ducts fails to reabsorb. This anomaly divides the vagina into 2 segments, reducing its functional length. TVS can be perforate or imperforate and can occur at nearly all levels in the vagina. Most of these septa are located in the superior vagina at the putative junction beween the vaginal plate and caudal aspect of the UVP (46%). The next most common locations are the mid vagina, at a rate of 40%, and the inferior vagina, at a rate of 14%.

The TVS is one of the most rare müllerian duct anomalies, with an approximate frequency of 1 case in 70,000 females. ^{[201, 202]} Unlike other müllerian duct anomalies, TVS is only occasionally associated with urologic defects. TVS has been associated with other structural anomalies, including imperforate anus, bicornuate uterus, coarctation of the aorta, atrial septal defect, and malformation of the lumbar spine. ^[202] No evidence indicates that this disorder is genetically inherited, although a study of an inbred Amish community suggested that hydromucocolpos due to obstructive TVS was the result of a rare autosomal disorder. ^[201]

Diagnosis of TVS - Fetuses, neonates, and infants

TVS is rarely diagnosed in the neonate or infant unless the obstruction causes a significant hydromucocolpos. In rare cases, copious amounts of fluid may collect in the vagina above the obstructing septum and create a mass effect in which the surrounding organs are compressed. Compression may cause serious consequences if not promptly diagnosed and treated. ^[67] Hydromucocolpos can be diagnosed in utero during third-trimester transabdominal sonography. In these cases, fetal abdominal distension is noted secondary to an abdominal or pelvic mass. ^[203]

Diagnosis of hydromucocolpos in the neonate and infant can be challenging. A large mass is often palpated in the lower abdomen. However, unlike an imperforate hymen, the obstruction is well in the vagina, and a bulging septum is not noted. Initial studies should include abdominal ultrasonography of the pelvis. ^[204] MRI should also be performed to help make a definitive diagnosis. MRI can also be useful to depict pelvic anatomy and determine the thickness of the vaginal septum. Proper imaging studies frequently eliminate the need for laparoscopy or laparotomy. ^[201]

Surgical management of TVS - Fetuses, neonates, and infants

When third-trimester ultrasonographic findings lead to the diagnosis, early delivery and drainage of the obstructed vagina and uterus are indicated when other organs are compromised. ^[203]

In infants, the vaginal septum is usually thin and can be corrected without extensive procedures. Surgical excision of the obstructed septum through a perineal approach is most efficacious. Bilateral incisions may be required to ensure complete removal. ^[67]

Postoperative management - Fetuses, neonates, and infants

Clinical follow-up is necessary because vaginal stenosis with subsequent accumulation of fluid may develop postoperatively. Vaginal reconstruction may be required to allow satisfactory menstruation and coitus.

Diagnosis of TVS – Postmenarche

In general, TVS remains undetected until the time of menarche. Presentation after menarche varies depending on whether the septum is complete or incomplete. If the TVS is complete, the patient commonly presents with primary amenorrhea and cyclic pelvic pain. Like an imperforate hymen, symptoms are caused by obstructed menstrual flow with retention of mucus, blood, or both. Physical examination frequently reveals a palpable central lower abdominal or pelvic mass secondary to hematocolpos, hematometra, hematosalpinx, and even hemoperitoneum. However, unlike an imperforate hymen, examination of the genitalia reveals no evidence of bulging at the introitus.

Incomplete TVS allows menstrual flow to escape periodically, but hematocolpos and hematometra often develop over time. Complaints include foul-smelling vaginal discharge, dyspareunia secondary to a short vagina, and infertility. In addition, TVS can cause soft tissue dystocia in patients who eventually become pregnant. ^[202]

Preoperative evaluation

Preoperative evaluation includes preliminary ultrasonography, MRI to determine the thickness of the vaginal septum, and IVP and renal sonography to help detect the occasional urinary tract anomaly. ^[67]

Surgical management of TVS - Adults

The surgical approach to TVS excision depends on the character, thickness, and location of the septum. The TVS can be thick in the adult, rendering its removal more difficult than in the infant. In some cases, a considerable length of vagina is underdeveloped, and it may rarely involve the entire vagina. For more extreme and complex cases, vaginoplasty similar to that used for MRKH syndrome may be indicated.

Surgical techniques

The approach to surgical correction of TVS depends on its location within the vagina and its thickness.

• High TVS

  • Surgical correction of high TVS is more difficult because the septum is usually thick and extensive; dissection between the bladder and the rectum is required. ^[198] The bladder and anteriorly associated structures are distinguished from the posterior rectum. A transurethral catheter is placed to provide the anterior boundaries.

  • A transverse incision is then made through the vaginal vault. If the TVS is imperforate, a portion of the septum is separated using blunt and sharp dissection. A probe is then introduced through the septum. Palpation of the urethral catheter anteriorly and a gloved rectal finger posteriorly provide identification of surgical landmarks so that neither the bladder nor the rectum is compromised. Blind dissection is continued until the cervix is palpated. The lateral margins of the septum are excised with a scalpel.

  • When a high hematocolpos cannot be drained vaginally, it may be necessary to perform an exploratory laparotomy. A probe is introduced through the uterine fundus and cervix to serve as a guide in locating the high hematocolpos. If a considerable amount of blood has accumulated in the obstructed upper vagina, an aspiration needle is used as a probe to identify it. The upper vagina is then entered.

  • When excision of a wide septum leaves an area too large to be closed using the available tissue, an indwelling stent is placed in the vagina to assist in epithelialization. If the septum is quite thick, excision may require the implantation of a split-thickness skin graft in a fashion similar to the McIndoe procedure. ^[205]

• Low, mid, and thin TVS

  • Thin, low, and mid vaginal septa are best excised with multiple radial incisions. The edges of the upper and lower vaginal mucosa are undermined and mobilized enough to permit anastomosis.

  • Joining of the upper and lower vaginal segments using interrupted delayed absorbable sutures follows this procedure. When the septal opening is small, manual dilation can be used. ^[205]

Postoperative management

The stent is left in place for 4-6 months. Daily dilation for the next 2-4 months is required to ensure continued vaginal patency. It is often necessary to make lateral incisions along the sides of the stent during removal. Coitus can be initiated, or, if the patient is not sexually active, a silicone vaginal form is inserted nightly until the constrictive phase of healing is complete. If a vaginal graft is placed, postoperative management is similar to that previously outlined for the McIndoe procedure (see Surgical techniques for müllerian aplasia [vaginal agenesis] in Class I - Vaginal Agenesis). Care must be taken to maintain good hemostasis, which avoids sloughing of the graft.

Routine postoperative care following vaginal surgery includes abstaining from intercourse for 1 month.

Complications and results

Complications include separation of the suture line joining the upper and lower vagina. In general, results are excellent. The procedures for both thick and thin vaginal septa result in a vagina that is only slightly shorter than average. Endometriosis from retrograde blood flow may occur in patients with TVS, especially when the septum is high. Prompt diagnosis and treatment to drain the accumulated blood may contribute to improved reproductive function. ^{[205, 46]} In some cases, the septa recur after surgery. ^[206]

Vaginal atresia

Vaginal atresia occurs when the UGS fails to contribute to the inferior portion of the vagina. ^[23] The müllerian structures are usually normal, but fibrous tissue completely replaces the inferior segment of the vagina. Although not müllerian in origin, vaginal atresia can clinically mimic vaginal agenesis and imperforate hymen and may be another anomaly in the continuum of segmental vaginal defects. ^[47] Surgical management is similar to that of vaginal agenesis.

Most cases of vaginal atresia occur sporadically. Some authors describe vaginal atresia as a component of an autosomal recessive syndrome characterized by anomalies of the middle ear ossicle and renal dysgenesis. ^[207] One report describes distal vaginal atresia occurring in a set of 14-year-old monozygotic twins. Although the author designated the anomaly vaginal agenesis, both twins had normal uteri and proximal vaginas indicating that this was not a müllerian defect. One twin also had a duplicated right ureter. ^[208]

Diagnosis of vaginal atresia

Children with this anomaly may develop pyometrocolpos and present with obstructive uropathy, septicemia, or renal failure. ^{[209, 210]} Young women with vaginal atresia usually present to the gynecologist with primary amenorrhea. Physical examination reveals age-appropriate developmental milestones, and secondary sexual characteristics are usually normal. A midline pelvic mass can often be palpated during the abdominal-rectal examination. Pelvic examination reveals findings of normal external genitalia; however, a vaginal dimple is present at the introitus. The karyotype is 46,XX, and the results from endocrine studies are normal.

Transperineal ultrasonography reveals the presence of ovaries, a uterus, a cervix, and an obstructed blind-ending superior vagina. All of these features distinguish vaginal atresia from vaginal agenesis. ^[211] MRI can aid in detecting the presence of a cervix, which should distinguish this anomaly from cervical agenesis, which is quite rare. This modality can further establish the presence of a functioning endometrial cavity. ^[212] These patients are not candidates for HSG studies.

Preoperative evaluation

Some authorities recommend nonsurgical methods as the first approach in managing vaginal atresia. ^[212] When nonsurgical methods fail, surgical approaches are recommended.

Surgical techniques and postoperative management

The modified McIndoe procedure is recommended (see Surgical techniques for müllerian aplasia [vaginal agenesis] in Müllerian Agenesis).

Complications and results

The same complications discussed previous for the McIndoe procedure apply (see Surgical complications and results in Müllerian Agenesis), though some surgeons have difficulty connecting the neovagina to the superior functioning vagina. After surgical correction, most patients can expect normal reproductive outcomes.

The 2021 ASRM müllerian classification includes in the Complex Anomalies the following ^[43] :

• Bicornuate uterus with bilateral obstructed endometrial cavities
• Bicornuate uterus with communicating tract (right or left) and transverse vaginal septum
• Obstructed hemivagina (right or left), hemiuterus, and single cervix with separate contralateral patent hemiuterus (right or left), cervix, and vagina
• Uterus isthmus agenesis

Müllerian anomalies are a morphologically diverse group of developmental disorders that involve the internal female reproductive tract. Establishing an accurate diagnosis is essential for planning treatment and management strategies. The surgical approach for correction of müllerian duct anomalies is specific to the type of malformation and may vary in a specific group. For most surgical procedures, the critical test of the procedure's value is the patient's postoperative ability to have healthy sexual relations and achieve successful reproductive outcomes.