Subinvolution of Placental Site

Subinvolution of the placental site is failure of the usual obliteration of the arteries at the placental attachment site after birth, so that large vessels remain open and cause sudden heavy bleeding, usually at 1 to 3 weeks, sometimes up to 12 weeks. It results from incomplete trophoblastic invasion changes, infection, retained placental tissue and local inflammation. It accounts for a large share of secondary postpartum haemorrhage, and matters because bleeding can be abrupt and severe.

• Risk factors: retained products, endometritis, previous caesarean section, uterine anomaly, multiple pregnancy, anaemia.
• The uterus is often soft, large and boggy.
• Histology of curettings shows vessels with trophoblast and no thrombosis.

Women have sudden heavy red bleeding with clots 1 to 3 weeks after birth, after a period of normal or diminishing lochia, with a soft, enlarged uterus and sometimes lower abdominal pain and low grade fever. The cervix may be open.

• Large soft uterus at the placental site.
• Bleeding that returns after settling.
• Differential diagnosis: retained placental fragments, endometritis, caesarean scar dehiscence, arteriovenous malformation, trophoblastic disease, coagulopathy, return of menstruation.
• Complications: haemorrhagic shock, anaemia, infection, repeated curettage, hysterectomy, infertility from adhesions.

The approach is ultrasound with colour Doppler, tests for infection and histology.

• Pelvic ultrasound with colour Doppler: enlarged uterus, thick endometrium, vascular placental site, with or without retained tissue; check for scar defect and arteriovenous malformation.
• Haemoglobin, white cell count, C-reactive protein, platelets, clotting screen, high vaginal swab, urine hCG, group and cross-match 2 to 4 units.
• Histology of any curettings to confirm the diagnosis and to exclude trophoblastic disease.
• Pulse, blood pressure, temperature, uterine size and tenderness.

The principle is resuscitation and uterotonic drugs with antibiotics, avoiding curettage unless tissue is retained, because it can worsen bleeding.

• Supportive: admit; two large-bore cannulae; Ringer's lactate 1 litre rapidly for shock; blood transfusion for haemoglobin below 7 g/dL or shock; uterine massage; empty the bladder; breastfeeding.
• Pharmacological: oxytocin 10 IU IM then infusion of 40 IU in 1 litre Ringer's lactate at 250 mL per hour for 4 hours; misoprostol 800 micrograms sublingual once; ergometrine 0.2 mg IM once, then methylergometrine 0.2 mg oral 8-hourly for 3 days (not in hypertension); tranexamic acid 1 g IV over 10 minutes, then 1 g oral 8-hourly for 3 days; ampicillin 2 g IV 6-hourly plus gentamicin 5 mg/kg IV once daily plus metronidazole 500 mg IV 8-hourly until afebrile for 48 hours, then amoxicillin-clavulanate 625 mg oral 8-hourly to complete 7 days; ferrous sulphate 200 mg oral 8-hourly for 3 months.
• Procedures: gentle suction evacuation under ultrasound guidance only for retained tissue, after antibiotics; balloon tamponade (300 to 500 mL sodium chloride 0.9 percent); uterine artery embolisation for persistent bleeding; hysterectomy for uncontrolled haemorrhage.
• Special groups: women with hypertension avoid ergometrine and use misoprostol 400 micrograms sublingual once instead.
• Red flags: heavy bleeding, shock, fever above 38 degrees Celsius, foul lochia, bleeding after curettage, rising hCG.
• Follow-up: haemoglobin at 24 hours and 2 weeks; ultrasound at 1 to 2 weeks; histology review; review at 6 weeks.