Uterine Atony

Uterine atony is failure of the uterine muscle to contract after birth, so the open blood vessels at the placental site continue to bleed. It is the commonest cause of postpartum haemorrhage and occurs after about 3 to 5 percent of births. Causes include overdistension, prolonged labour, oxytocin exhaustion, infection, retained tissue, uterine fibroids and drugs such as magnesium sulphate and nifedipine.

• Risk factors: twin pregnancy, polyhydramnios, macrosomia, grand multiparity, prolonged labour, chorioamnionitis, previous atony, general anaesthesia.
• A full bladder and retained clots prevent contraction.
• Active management of the third stage prevents most cases.

Women have heavy bleeding after the placenta delivers, with a soft, boggy uterus that rises above the umbilicus and does not feel like a firm round mass, and signs of blood loss. Bleeding eases with massage.

• Soft, ill-defined uterus.
• Blood and clots with massage.
• Differential diagnosis: retained placenta or tissue, genital tract tear, uterine inversion, uterine rupture, coagulopathy, haematoma.
• Complications: haemorrhagic shock, coagulopathy, acute kidney injury, Sheehan syndrome, hysterectomy, maternal death.

The diagnosis is clinical, with tests to measure loss and exclude other causes.

• Palpate the fundus for tone and height; empty the bladder; measure blood loss; check the placenta and genital tract.
• Pulse, blood pressure, shock index, urine output.
• Haemoglobin, platelets, fibrinogen, clotting screen, group and cross-match 4 units.
• Ultrasound for retained tissue or clots.

The principle is prevention with oxytocin, and treatment by massage and a sequence of uterotonics, then mechanical and surgical steps.

• Supportive: call for help; two large-bore cannulae; Ringer's lactate 1 to 2 litres rapidly; oxygen; empty the bladder; uterine massage and bimanual compression; remove clots; early breastfeeding; transfusion for shock.
• Pharmacological: prevention: oxytocin 10 IU IM within 1 minute of birth, or carbetocin 100 micrograms IV slowly at caesarean section, or misoprostol 600 micrograms oral where oxytocin is unavailable; treatment: oxytocin 10 IU IM or 5 IU slow IV then infusion of 40 IU in 1 litre Ringer's lactate at 250 mL per hour; ergometrine 0.2 mg IM (repeat after 15 minutes, maximum 1 mg in 24 hours); misoprostol 800 micrograms sublingual once; carboprost 250 micrograms IM every 15 minutes (maximum 8 doses); tranexamic acid 1 g IV over 10 minutes (repeat once after 30 minutes if bleeding continues); ampicillin 2 g IV plus gentamicin 5 mg/kg IV once daily if infection is suspected.
• Procedures: uterine balloon tamponade (300 to 500 mL sodium chloride 0.9 percent, removed after 12 to 24 hours); B-Lynch compression suture; uterine and internal iliac artery ligation; embolisation where available; hysterectomy for uncontrolled bleeding.
• Special groups: hypertension, preeclampsia or heart disease avoids ergometrine; asthma avoids carboprost; heart disease uses oxytocin as a slow infusion with no bolus; women who decline transfusion have cell salvage and early surgery.
• Red flags: blood loss above 1000 mL, pulse above 120 per minute, systolic blood pressure below 90 mmHg, bleeding after 3 uterotonics, fibrinogen below 2 g/L.
• Follow-up: uterine tone and bleeding every 15 minutes for 2 hours then hourly for 6 hours; haemoglobin at 6 and 24 hours; ferrous sulphate 200 mg oral 8-hourly for 3 months; review at 6 weeks; plan the next birth with oxytocin ready and IV access.