Single Best Answer (SBA) · Postpartum Haemorrhage and Third-Stage Complications

A woman has heavy vaginal bleeding immediately after delivery of the placenta. The uterus feels soft and poorly contracted. What is the single commonest cause of this primary postpartum haemorrhage?

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Answer: D. Uterine atony

Primary postpartum haemorrhage is the loss of 500 ml or more of blood from the genital tract within 24 hours of birth.

The 4 Ts (causes of PPH)	Examples
Tone (commonest)	Uterine atony: multiple gestation, macrosomia, polyhydramnios, prolonged or rapid labour, retained placenta, drugs, infection, Couvelaire uterus
Tissue	Retained placenta or products of conception
Trauma	Genital tract trauma (tears, episiotomy, uterine rupture, inversion)
Thrombin	Coagulopathy (e.g. DIC, including after amniotic fluid embolism or abruption)

A soft, poorly contracted uterus points to uterine atony (Tone), the commonest cause of primary PPH.
Atony is failure of the uterus to contract after delivery of the placenta, so the living-ligature mechanism fails and the placental bed bleeds.

Atony is not the same as 'uterine inertia' (absence of effective contractions during labour); atony refers to the postpartum uterus.

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