Subserosal Fibroid

A subserosal fibroid is a smooth muscle tumour that grows from the outer wall of the uterus and projects into the pelvis or abdomen. It may be broad-based or on a stalk.

• It usually causes pressure symptoms rather than heavy bleeding.
• Large fibroids can compress the bladder, ureters and bowel.
• Surgery is chosen for symptoms, rapid growth or fertility needs.

Pelvic or abdominal mass, pressure, urinary frequency, constipation, backache, dyspareunia and sometimes acute pain; menstrual flow is often normal.

• A firm, irregular, mobile pelvic or abdominal mass moving with the uterus.
• Differential diagnosis: ovarian tumour, intramural fibroid, adenomyosis, pedunculated fibroid, leiomyosarcoma, pelvic kidney, bowel mass.
• Complications: torsion of a stalked fibroid, red degeneration, hydronephrosis, bowel obstruction, venous compression, and rarely sarcoma.

Diagnosis is by ultrasound, with MRI or CT to show the origin of the mass.

• Abdominal and transvaginal ultrasound.
• Pelvic MRI or CT scan to show origin and relation to the uterus, ovaries, ureters and bowel.
• Full blood count; ferritin; pregnancy test; renal ultrasound; CA-125 if an ovarian tumour is possible.
• Histology after surgery.

Observe asymptomatic fibroids and operate for pressure symptoms, torsion or rapid growth.

• Supportive: observe asymptomatic fibroids with ultrasound every 6 to 12 months; counselling on symptoms of torsion; pelvic support if heavy.
• Pharmacological: ibuprofen 400 mg oral 8-hourly with food (maximum 1.2 g in 24 hours) and paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours) for pain. Leuprorelin 3.75 mg IM every 4 weeks for up to 3 months to shrink the fibroid before surgery. Anaemia: ferrous sulphate 200 mg oral 8-hourly, continued for 3 months after haemoglobin normalises. Tranexamic acid 1 g oral 8-hourly for up to 4 days if bleeding is heavy (maximum 4 g in 24 hours).
• Procedures: laparoscopic or open myomectomy; hysterectomy when fertility is complete; urgent laparotomy for torsion; uterine artery embolisation for selected women; ureteric stent when ureters are compressed.
• Special groups: in pregnancy give paracetamol and rest for pain; avoid ibuprofen from 28 weeks; expect red degeneration in the second trimester. Avoid GnRH analogues and tranexamic acid in pregnancy.
• Red flags: sudden severe pain with vomiting (torsion), fever with pain (infected degeneration), urinary retention, hydronephrosis, rapid growth.
• Follow-up: review at 6 weeks after surgery; ultrasound at 6 to 12 months if observed.