You are in: eMedicine Specialties > Radiology > OBSTETRICS/GYNECOLOGY Leiomyoma, Uterus (Fibroid)Article Last Updated: May 6, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Philip Thomason, MD, Director of Diagnostic Radiology, Department of Radiology, Beverly Hospital Philip Thomason is a member of the following medical societies: American College of Radiology, Massachusetts Medical Society, and Radiological Society of North America Editors: Christopher L Sistrom, MD, Associate Chair for Research, Assistant Professor, Department of Radiology, University of Florida School of Medicine; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Karen L Reuter, MD, FACR, Professor, Department of Radiology, Lahey Clinic Medical Center; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Eugene C Lin, MD, Clinical Assistant Professor of Radiology, University of Washington Medical School Author and Editor Disclosure Synonyms and related keywords: leiomyoma, uterine; myoma, uterus; fibromyomas, uterus; leiomyomata; benign tumors of the uterus; fibroids; myomectomy; subserosal fibroid; exophytic fibroid; submucosal fibroid; subendometrial fibroid; intramural fibroid INTRODUCTIONSection 2 of 11
  BackgroundLeiomyomas are benign tumors of the uterus. For excellent patient education resources, visit eMedicine's Women's Health Center. Also, see eMedicine's patient education article Fibroids. PathophysiologyLeiomyomas arise from the overgrowth of smooth muscle and connective tissue in the uterus. A genetic predisposition exists. Histologically, a monoclonal proliferation of smooth muscle cells occurs. Evidence of an apparent hormonal dependency includes the following:
FrequencyUnited StatesLeiomyoma is the most frequently diagnosed gynecologic tumor, occurring in 20-50% of women older than 30 years.1 Mortality/MorbidityRarely, uterine leiomyoma may undergo malignant degeneration to become a sarcoma. The true incidence of malignant transformation is difficult to determine, because leiomyomas are common, whereas malignant leiomyosarcomas are rare and can arise de novo. The incidence of malignant degeneration is less than 1.0% and has been estimated to be as low as 0.2%. Infertility may occur as a result of narrowing of the isthmic portion of the fallopian tube or as a consequence of interference with implantation, especially inference caused by submucosal fibroids. Complications during pregnancy include spontaneous abortion, intrauterine growth retardation, preterm labor, uterine dyskinesia or inertia during labor, obstruction of the birth canal, postpartum hemorrhage, and hydronephrosis. RaceLeiomyomas occur more commonly in black women (3:1) than they do in white women (9:1). A genetic predisposition exists.2 SexUterine leiomyomas occur only in females. AgeLeiomyomas occur most commonly in women older than 30 years, but they may develop in females of any age. AnatomyMost leiomyomas occur in the fundus and body of the uterus; only 3% occur in the cervix. The fibroids may be solitary, multiple, or diffuse. Most fibroids (95%) are intramural, being located in the middle of the myometrium. Subserosal, or exophytic, fibroids are located in the subserosal layer and tend to cause a focal bulge in the exterior surface of the uterus; they can become pedunculated. Rarely, subserosal fibroids occur in the broad ligament. Submucosal, or subendometrial, fibroids are the least common. They distort the overlying endometrium and can become extruded or pedunculated (ie, fibroid polyps) in the endometrial canal. Clinical DetailsMost women with fibroids are asymptomatic. Only 10-20% of patients require treatment. Fibroid symptoms are related to the number of tumors, as well as to their size and location. Symptoms may include the following:
Preferred ExaminationThe preferred imaging modality for the evaluation of uterine fibroids is ultrasonography (US), specifically, transabdominal and transvaginal US. Calcified fibroids are often depicted on conventional radiographs of the pelvis. In some patients, magnetic resonance imaging (MRI) provides additional information. The role of computed tomography (CT) scanning is limited. Calcifications may be more visible on CT scans than on conventional radiographs because of the superior contrast differentiation achieved with CT scanning.3, 4 Limitations of TechniquesIn the detection of uterine fibroids, CT scanning is limited by the similar attenuation characteristics of fibroids and healthy myometrium, although some fibroids may be hypoattenuating. Fibroid calcifications can be depicted on CT scans. DIFFERENTIALSSection 3 of 11
Ovary, Malignant Tumors Other Problems to Be ConsideredNormal ovary - May be confused with fibroids at US RADIOGRAPHSection 4 of 11
FindingsConventional radiographs have a limited role in the diagnosis of uterine fibroids. Unless heavily calcified, fibroids are not depicted on radiographs. Extreme enlargement of the uterus resulting from fibroids may be seen as a nonspecific soft-tissue mass of the pelvis that possibly displaces loops of bowel. CT SCANSection 5 of 11
FindingsCT scanning has a limited role in the diagnosis of uterine fibroids. On CT scans, fibroids are usually indistinguishable from healthy myometrium unless they are calcified or necrotic. Calcifications may be more visible on CT scans than on conventional radiographs because of the superior contrast differentiation with CT scanning. MRISection 6 of 11
FindingsMRI has an important role in defining the anatomy of the uterus and ovaries, as well as in assessing disease in patients in whom US findings are confusing. MRI also may be helpful in planning myomectomy, or selective surgical removal of a fibroid. Fibroids are sharply marginated areas of low-to-intermediate signal intensity on T1- and T2-weighted MRI scans (see Image 5). One third of fibroids have a hyperintense rim on T2-weighted images as a result of dilated veins, lymphatics, or edema (see Images 6-7). An inhomogeneous area of high signal intensity may be depicted on T2-weighted images; this results from hemorrhage, hyaline degeneration, edema, or highly cellular fibroids (see Image 3). The intravenous administration of gadolinium-based contrast material usually is not required; however, if it is administered, fibroids usually enhance later than does the healthy myometrium. Fibroid enhancement can be hypointense (65%), isointense (23%), or hyperintense (12%) in relation to that of the myometrium. Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or magnetic resonance angiography (MRA) scans. The primary limitation of MRI is the high cost. Its availability in terms of time and location is another factor that determines its usefulness. Additionally, patients with pacemakers or certain metallic foreign bodies cannot undergo MRI. Claustrophobia is a relative contraindication. Degree of ConfidenceMRI has a sensitivity of 86-92%, a specificity of 100%, and an accuracy of 97% in the evaluation of probable fibroids. ULTRASOUNDSection 7 of 11
FindingsUS is the imaging modality of choice in the detection and evaluation of uterine fibroids.5, 6, 7 The most frequent US appearance is that of a concentric, solid, hypoechoic mass (see Images 1-2). This appearance results from the prevailing muscle, which is observed at histologic examination. These solid masses absorb sound waves and therefore cause a variable amount of acoustic shadowing. Fibroids may vary in their degree of echogenicity; they can be heterogeneous or hyperechoic, depending on the amount of fibrous tissue and/or calcification (see Image 4). Fibroids may have anechoic components resulting from necrosis. Most fibroids are intramural, that is, located in the myometrium; however, they can be submucosal or subserosal. If fibroids are small and isoechoic relative to the uterus, the only ultrasonographic sign may be a bulge in the uterine contour. Fibroids in the lower uterine segment may obstruct the uterine canal, causing fluid to accumulate in the endometrial canal. The echogenic endometrial stripe may be displaced by a fibroid. Calcifications are hyperechoic, with sharp acoustic shadowing. Diffuse leiomyomatosis appears as an enlarged uterus with abnormal echogenicity. Degree of ConfidenceUS has a sensitivity of 60%, a specificity of 99%, and an accuracy of 87%. False Positives/NegativesAlthough the ultrasonographic appearance of fibroids usually is diagnostic, in fewer than 5% of patients, fibroids (especially when necrotic) may mimic normal pelvic structures (particularly the ovaries) and pathologic pelvic conditions, including uterine variants and pregnancy-related conditions (see Other Problems to Be Considered). MRI results often clarify confusing pelvic ultrasonographic findings. ANGIOGRAPHYSection 8 of 11
FindingsAlthough angiography has no role in the diagnosis of uterine fibroids, it is used to guide the uterine arterial embolization (UAE) of fibroids. INTERVENTIONSection 9 of 11
The treatment of symptomatic uterine fibroids ranges from conservative medical management of symptoms to hysterectomy. Selective myomectomy, UAE, or fibroid embolization also can be performed.8 UAE is a minimally invasive procedure performed by an interventional radiologist. Typically, UAE is carried out via a percutaneous femoral arterial approach. Both of the uterine arteries are individually selected with angiographic guidance and are embolized with 300-500 µm polyvinyl alcohol (PVA) foam particles.9 Although it is a fairly new procedure, UAE has been performed in more than 5,000 patients in the United States and in more than 10,500 patients worldwide, with good results and low complication rates.10 Medical/Legal Pitfalls
Special Concerns
MULTIMEDIASection 10 of 11
REFERENCESSection 11 of 11
Leiomyoma, Uterus (Fibroid) excerpt Article Last Updated: May 6, 2008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
