Also known as leiomyomata, fibroids are BENIGN tumours of the muscle layers of the uterus (see UTERUS, DISEASES OF). They are the most common tumours of the female genital tract; at least 25 per cent of women will develop a fibroid, usually between 30–50 years old. Fibroids are more common with increasing age, in African and Afro-Caribbean women, and in women who postpone childbearing. The exact cause is unknown. They are categorised according to location: intramural fibroids are the most common and occur in the wall of the uterus; subserosal fibroids protrude outside of the uterus and can be very large; submucosal fibroids are the least common and occur in the inner muscle lining the uterus.

Most women have no symptoms so fibroids are often discovered during a routine examination. When symptoms occur they relate mainly to the location and size and may include heavy or painful periods, abdominal discomfort or bloating, backache, and subfertility. The diagnosis can be made by transabdominal or transvaginal ULTRASOUND. Fibroids in the inner lining or cavity of the uterus can be seen with a hysteroscope (see HYSTEROSCOPY) and those outside the uterus with a LAPAROSCOPE. Magnetic resonance imaging (MRI) can be used when the diagnosis is uncertain.

Treatment is not always necessary and is primarily to relieve symptoms. Gonadotrophin-releasing hormone analogues are often used to shrink fibroids but can only be used in the short term. Other medical treatments include tranexamic acid, non-steroidal anti-inflammatory drugs, and the contraceptive pill. Surgery is the only long term solution, the choice of which depends on the site and size of the fibroid. Surgical options include MYOMECTOMY (removing the fibroids), HYSTERECTOMY (removing the uterus), endometrial ABLATION (removing the lining of the uterus), and uterine artery embolisation (blocking the blood supply to the fibroid). Fibroids can recur after all treatments, apart from hysterectomy. The risk of recurrence after myomectomy is about 50 per cent.