Postpartum Uterine Atony

Uterine atony is failure of the uterus to contract adequately after delivery. It causes about 70% of all postpartum haemorrhage (PPH). PPH is blood loss of at least 500 mL after vaginal delivery or 1,000 mL after caesarean; severe at 1,000 mL or more; primary within 24 hours.

PPH complicates about 3 to 5% of births and is the leading cause of maternal mortality worldwide (about 25%). Myometrial contraction normally compresses spiral arteries ("living ligatures"); atony prevents this.

Risk factors:

• Uterine overdistension (multiple pregnancy, polyhydramnios, macrosomia).
• Prolonged or rapid labour, prolonged oxytocin use.
• High parity, chorioamnionitis.
• Retained products or placenta, uterine fibroids or anomalies.
• Previous PPH.
• General anaesthesia (halogenated agents), magnesium sulfate, tocolytics (nifedipine, terbutaline).
• Obesity, advanced maternal age.
• Placenta praevia or abruption.

• Heavy vaginal bleeding after delivery of the placenta (dark blood with clots), or concealed bleeding into the uterus
• Soft, boggy, enlarged uterine fundus above the umbilicus that fails to firm after massage
• Signs of hypovolaemia: tachycardia, pallor, hypotension (a late sign), anxiety, cold clammy skin, oliguria, and altered consciousness
• Shock index (heart rate/systolic BP) above 0.9 predicts need for transfusion; obstetric early warning score
• Coagulopathy in prolonged bleeding

• Clinical, based on bimanual examination of the uterus and quantitative blood loss assessment (weigh swabs, collection drapes)
• Systematically exclude other causes (the "4 Ts": Tone, Trauma, Tissue, Thrombin): genital tract lacerations (examine cervix and vagina), retained placenta or fragments, uterine rupture or inversion, and coagulopathy
• Investigations: full blood count, fibrinogen, coagulation, group and crossmatch, lactate, blood gas, and ultrasound for retained tissue
• Fibrinogen below 2 g/L is predictive of severe PPH

Immediate measures. Call for help and start ABC resuscitation. Give oxygen at 10 to 15 L/min. Insert two large bore cannulae. Send bloods (including fibrinogen) and crossmatch. Give warm crystalloid. Empty the bladder (indwelling catheter). Perform uterine massage (rubbing up a contraction).

Stepwise uterotonic therapy.

1. Oxytocin 5 to 10 IU slow IV (or 10 IU IM), followed by infusion of 40 IU in 500 mL crystalloid at about 125 mL/hour (10 IU/hour)
2. Ergometrine 0.25 mg IM or slow IV (contraindicated in hypertension, pre-eclampsia, cardiac disease) or syntometrine (oxytocin 5 IU with ergometrine 0.5 mg) IM
3. Carboprost (15-methyl PGF2 alpha) 250 micrograms IM (or intramyometrial) every 15 minutes, maximum 8 doses (contraindicated in asthma; causes bronchospasm, vomiting, diarrhoea)
4. Misoprostol 800 micrograms sublingually or 1,000 micrograms rectally
5. Tranexamic acid 1 g IV over 10 minutes within 3 hours of birth (repeat once after 30 minutes if bleeding continues)

Mechanical and surgical measures.

• Bimanual uterine compression
• Intrauterine balloon tamponade (Bakri balloon or Foley with condom): fill with 300 to 500 mL warmed saline (80 to 500 mL according to uterine size). Success about 85%.
• Leave the balloon in situ for 12 to 24 hours with oxytocin infusion, antibiotic cover (cefazolin 2 g IV), and slow deflation
• Uterine compression sutures (B-Lynch, Hayman, Cho) via laparotomy
• Stepwise devascularisation (uterine, utero ovarian and internal iliac artery ligation)
• Interventional radiology: uterine artery embolisation (success 85 to 95% in haemodynamically stable patients)
• Peripartum hysterectomy (subtotal or total) is the definitive life saving procedure, and should not be delayed in uncontrolled haemorrhage
• Non-pneumatic anti-shock garment in low resource settings and aortic compression as a temporising measure

Resuscitation and blood products.

• Target haemoglobin above 8 g/dL (red cells).
• Fibrinogen above 2 g/L (cryoprecipitate or fibrinogen concentrate 2 to 4 g).
• Platelets above 50,000/microlitre.
• Fresh frozen plasma (12 to 15 mL/kg) if PT/aPTT above 1.5 times.
• Massive transfusion protocol (red cells, plasma, platelets in ratio 1:1:1 or 4:4:1) with calcium, warm products, and cell salvage.
• Monitor with ROTEM or TEG.

Prevention. Active management of the third stage is routine in all women: oxytocin 10 IU IM within 1 minute of birth, controlled cord traction, and uterine massage. Give carbetocin 100 micrograms IV for caesarean section (heat stable, longer acting). Assess risk on admission, with IV access and crossmatch in high risk women.

After care. HDU or ICU monitoring, transfusion and iron replacement (IV iron after stabilisation), thromboprophylaxis once bleeding controlled, debriefing, and screening for Sheehan syndrome and postnatal depression.