Uterine Arteriovenous Malformation

Uterine arteriovenous malformation is an abnormal direct connection between uterine arteries and veins in the myometrium. It may be congenital or acquired after curettage, caesarean delivery, miscarriage, abortion or gestational trophoblastic disease.

• It causes sudden, severe, recurrent vaginal bleeding that can be life-threatening.
• Dilatation and curettage can provoke catastrophic haemorrhage and must be avoided.
• Embolisation is the main treatment.

Sudden heavy vaginal bleeding days to weeks after abortion, miscarriage, delivery or curettage; intermittent or continuous bleeding that does not respond to uterotonics.

• Pelvic bruit or thrill; enlarged uterus; anaemia and shock.
• Differential diagnosis: retained products of conception, gestational trophoblastic disease, endometrial polyp, submucosal fibroid, placenta accreta, caesarean scar pregnancy, uterine rupture.
• Complications: hypovolaemic shock, anaemia, hysterectomy, infertility and heart failure from large shunts.

Diagnosis is by Doppler ultrasound, confirmed by angiography, after exclusion of pregnancy and retained tissue.

• Pregnancy test and beta human chorionic gonadotrophin to exclude trophoblastic disease and retained tissue.
• Transvaginal ultrasound with colour Doppler showing a vascular network with high-velocity, low-resistance flow in the myometrium.
• Contrast CT angiography or MRI angiography; catheter angiography is the confirmatory test and allows treatment.
• Full blood count; group and cross-match; clotting screen.

Resuscitate, avoid curettage, and treat with uterine artery embolisation.

• Supportive: resuscitation with IV crystalloid and blood transfusion when haemoglobin is below 7 g/dL or in shock; two large IV lines; avoid curettage or vacuum aspiration; keep the woman in a facility with interventional radiology and theatre.
• Pharmacological: tranexamic acid 1 g IV over 10 minutes, repeated once after 30 minutes if bleeding continues, then 1 g oral 8-hourly for up to 4 days (maximum 4 g in 24 hours). Minor stable bleeding is observed with tranexamic acid and repeat Doppler ultrasound. Iron: ferrous sulphate 200 mg oral 8-hourly, continued for 3 months after haemoglobin normalises.
• Procedures: uterine artery embolisation as first-line treatment; hysteroscopic resection of small superficial malformations; laparotomy with uterine artery ligation or hysterectomy for uncontrolled bleeding or when embolisation is unavailable.
• Special groups: in women who want pregnancy, embolisation with particles preserves the uterus; counsel on later placental problems. In renal impairment, reduce tranexamic acid to 15 mg/kg (usually 1 g) oral 12-hourly when creatinine is 120 to 249 micromol/L, and limit contrast use.
• Red flags: shock, bleeding after dilatation and curettage, continued bleeding after embolisation, heart failure.
• Follow-up: Doppler ultrasound at 1, 3 and 6 months; haemoglobin and ferritin; early ultrasound in any future pregnancy.