Antepartum haemorrhage — praevia vs abruption
Placenta praevia versus abruptio placentae side by side, plus vasa praevia as the third differential.
Define the problem
Antepartum haemorrhage (APH) is bleeding from the genital tract after 28 weeks and before delivery. The two big causes are placenta praevia (low-lying placenta) and abruptio placentae (premature separation of a normally situated placenta). Separate them by one question first: is there pain? Praevia is painless; abruption hurts.
Praevia vs abruption — side by side
| Feature | Placenta praevia | Abruptio placentae |
|---|---|---|
| Pain | Painless | Painful, constant |
| Bleeding character | Revealed, bright red, recurrent; amount = visible loss | May be concealed or revealed; dark; visible loss underestimates true loss |
| Uterine tone | Soft, relaxed, non-tender | Tense, "woody" hard, tender |
| Fetal status | Usually well (presenting part high) | Distress or death common (placental separation) |
| Presenting part | High/floating, malpresentation frequent | Engaged, normal lie usual |
| Shock vs visible loss | Proportionate | Out of proportion (hidden blood + DIC) |
| Examination caution | NEVER do a digital vaginal exam — provokes torrential bleeding; confirm site by ultrasound first | Speculum to exclude local cause; watch for DIC and renal failure |
| Associations | Prior LSCS/uterine scar, multiparity, multiple pregnancy | Hypertension/pre-eclampsia, trauma, sudden uterine decompression, cocaine, high parity |
Complications that separate them
- Praevia → recurrent bleeds, malpresentation, postpartum haemorrhage (lower-segment placenta implants on poorly contractile muscle), placenta accreta if a scar underlies it.
- Abruption → Couvelaire uterus (blood infiltrates myometrium), DIC, acute tubular necrosis, fetal death.
The third differential — vasa praevia
Vasa praevia: fetal vessels (from a velamentous cord insertion or a succenturiate lobe) cross the internal os, unprotected by cord or placenta. Classic triad: painless bleeding + rupture of membranes + acute fetal distress/bradycardia. The blood is fetal, so a small loss is catastrophic for the baby though the mother stays stable. It is the one APH where the fetus exsanguinates while the mother looks fine — an emergency caesarean.
Pearl: painless soft uterus, well baby, no PV exam → praevia; painful woody uterus, distressed baby, shock out of proportion → abruption; painless bleed at membrane rupture with sudden fetal bradycardia → vasa praevia.
Sources
- DC Dutta's Textbook of Obstetrics, 9e
- Williams Obstetrics, 26e