Practice Essentials
A rectovaginal fistula (RVF) is an epithelial-lined tract between the rectum and vagina. [1] For thousands of years, women simply tolerated the distressing symptoms generated by RVFs. Today, there is no need for such tolerance, because most RVFs can be surgically corrected via a number of approaches. [2] A small percentage, however, cannot be corrected, because of patient comorbidity or disease-related factors; in these cases, patients can be helped only by fecal diversion. [3]
This article discusses only acquired RVFs. Most RVFs are located at or just above the dentate line. Fistulas below the dentate line are not true RVFs but, rather, anovaginal fistulas; the treatment required for these differs from that required for RVFs.
Anatomy
The rectovaginal septum is the thin septum separating the anterior rectal wall and the posterior vaginal wall. The caudal portion of the septum is the perineal body. The anal sphincters are located in the posterior portion of the perineal body. The transverse perineal muscle traverses the perineal body and is often used in anal sphincteroplasty and RVF repair.
The dentate line is the grossly visible demarcation between the squamous anal epithelium and the transitional-columnar epithelium of the rectum. The anal glands open into the bases of the anal crypts at this location.
The lowest extent of the peritoneal cavity in the female lies in the pelvis and may be anterior to the cervix uteri, posterior to it, or both. The occupation of this space by the small bowel is called an enterocele; when the space is occupied by the sigmoid colon, this is termed a sigmoidocele.
Pathophysiology
Several traumatic mechanisms for the development of RVF exist. Perineal lacerations during childbirth, especially those due to episioproctotomy, predispose patients to RVFs. Perineal lacerations are more common in primigravidas, in precipitous births, or when forceps or vacuum extraction is used. Failure to recognize and correctly repair perineal lacerations, or secondary infection of perineal lacerations, further increases the chance of RVF. Prolonged labor with pressure on the rectovaginal septum can produce necrosis and result in RVF.
Vaginal or rectal operative procedures, especially those performed near the dentate line, may cause RVFs. Stapled hemorrhoidopexy, STARR (stapled transanal rectal resection), and TRANSTAR (transanal stapler-assisted resection) have been increasingly associated with RVFs. [4] Pelvic operations can be complicated by the development of a high RVF.
Traumatic injury (penetrating or blunt) and forceful coitus also have produced RVFs.
Crohn disease [5] and, less often, ulcerative colitis have been associated with RVFs. The fistula may arise primarily or, more often, in relation to a perirectal abscess or fistula, manifesting as complicated perianal sepsis.
The use of radiation to treat pelvic malignancies may give rise to RVFs. [6] Fistulas that occur during such therapy usually result from tumor regression. Most other fistulas become apparent 6 months to 2 years after completion of treatment. Diabetes, hypertension, smoking, and previous abdominal or pelvic surgery increase the risk of fistula formation. The use of biopsy to differentiate radiation-related change at the fistula from a recurrent tumor is imperative, because neoplasms (primary, recurrent, or metastatic) can produce RVFs.
A variety of infectious conditions can produce RVF. The most common are perirectal abscess/fistula and diverticulitis. Less commonly, tuberculosis, lymphogranuloma venereum, and Bartholin gland abscess can cause RVFs.
Etiology
The most common etiology for RVF of traumatic origin, and probably for all RVFs, is obstetric injury. [7, 8, 9] Other etiologies for RVF include the following:
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Inflammatory bowel disease (IBD), most often Crohn disease [5]
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Operative trauma
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Infectious etiologies
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Neoplasm
Epidemiology
Among reported series, the frequency with which RVFs occur varies according to the cause. RVFs are classified on the basis of location, size, and etiology (see Etiology), each of which affects the treatment plan and prognosis.
RVFs can be divided into the following two groups on the basis of location:
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Low RVFs, which are located between the lower third of the rectum and the lower half of the vagina, are closest to the anus and can be corrected with a perineal approach
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High RVFs, which occur between the middle third of the rectum and the posterior vaginal fornix, require a transabdominal approach for repair
RVFs may vary greatly in size, but most are less than 2 cm in diameter. They are stratified by size as follows:
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Small RVFs are less than 0.5 cm in diameter
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Medium-sized RVFs are 0.5-2.5 cm in diameter
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Large RVFs exceed 2.5 cm in diameter
Prognosis
Local repair
Transanal advancement flap repair is a very safe approach. Results are good to excellent, with success reported in 77-100% of patients in various series. Preoperative assessment of anal sphincter integrity is important. Sphincter repair is easily performed simultaneously and increases the success rate of RVF repair. Vaginal childbirth after RVF repair is not associated with an increased risk of RVF recurrence. However, if a sphincter repair is performed along with the RVF repair, many surgeons recommend cesarean delivery for subsequent pregnancies in order to avoid disruption of the sphincteroplasty.
Transvaginal inversion repair and conversion to complete perineal laceration with layer closure can yield acceptable results in selected cases.
Bioprosthetic repair is a newer technique for RVF repair. Early experience indicates that it produces results that are equal or superior to those of advancement flap repair. [10] The button fistula plug has been successful in 58% of rectovaginal and ileal pouch–vaginal fistulas. [11]
Simple fistulotomy is suitable only for true anovaginal fistulas, which incorporate no sphincter muscle whatsoever. Application of this technique to RVF results in incontinence.
Transabdominal repair
With approximation of healthy tissue in the absence of inflammation, infection, or tension, transabdominal repairs yield good long-term results. It is essential always to consider the morbidities of major abdominal surgery and any comorbid conditions related to the patient's history.
Patients with fistulas due to radiation may have added morbidities associated with other irradiated tissues, such as the following:
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Cystitis
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Ureteral complications, including stricture and obstruction
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Vascular injury, including stenosis and occlusion
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Small-bowel injury, including stricture, malabsorption, and obstruction
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Neurologic complications
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Bony complications, including necrosis and fractures
Using American College of Surgeons National Surgical Quality Improvement Program (NSQIP) data, Raju et al compared perioperative outcomes in 2288 women with an RVF who underwent repair via either a transvaginal/perineal approach (n = 1560) or an abdominal approach (n = 728). [12] Those who underwent transabdominal repair were older, had more comorbid conditions, and had higher postoperative complication rates. Regardless of the surgical approach followed, American Society of Anesthesiologists (ASA) class, disseminated cancer, and preoperative anemia were associated with higher postoperative morbidity.
Recurrent rectovaginal fistula
Recurrence of an RVF indicates a poorer prognosis for future repair attempts. [13] In a study by Schouten et al, rectal sleeve advancement had an overall healing rate of 75% for persistent RVFs. [14] Recurrence is influenced by the etiology of the fistula and by its complexity. Fistulas of obstetric origin and fistulas that are considered simple (rather than complex) fare better after repeated repair attempts.
Byrnes et al, in a retrospective cohort study assessing the outcomes of primary surgical repair of RVF in relation to fistula etiology and specific surgical approach, found that the surgical approach affected recurrence-free survival at 1 year, with a rate of 35.2% for the local approach, 55.6% for the transvaginal or endorectal approach, 95% for the abdominal approach, and 33.3% for diversion only. [15] Fistula etiology did not significantly affect recurrence-free survival.
