Fibroids

Synonyms/Description

Leiomyoma, myoma, fibromyoma, and uterine fibroma

Etiology

Fibroids are the most common benign pelvic tumor in women. The prevalence in women age 50 and older is estimated at 80% in African Americans and up to 70% in Caucasians. Others have estimated a lower incidence (up to 50% of perimenopausal women).

Myomas are thought to be monoclonal and originate from a single myocyte that undergoes somatic mutation as it grows. Cytogenetic anomalies are found in 40% of fibroids. Estrogen and progesterone are known to stimulate the growth of fibroids. Although many fibroids are asymptomatic, others may cause bleeding, pain, mass effect, urinary frequency, constipation, pregnancy loss, and infertility. The presence of symptomatic fibroids is the most common indication for hysterectomy.

Ultrasound Findings

Fibroids are typically solid masses, which are sonographically hypoechoic or isoechoic with the surrounding myometrium. They are well circumscribed, with acoustic shadowing, often with a pattern of stripes or swirls caused by these shadows. They can be calcified, often with a circumferential pattern of calcification. If they degenerate, they can have central cystic portions. Color Doppler findings of fibroids are variable. Some fibroids have abundant flow and others scant; therefore there is no Doppler flow pattern specific to fibroids. Doppler is helpful to map the blood flow to the fibroid. If it is pedunculated, it may be confused with an ovarian mass.

Fibroids are further described by their location in the uterus.