Bleeding after 28 weeks (in India; 20–24 weeks elsewhere) is placenta praevia or abruptio placentae until proven otherwise — and they look opposite at the bedside.
How it's asked: A vignette of painless vs painful bleeding: identify the cause, the investigation (ultrasound) and the one thing never to do (a vaginal examination in praevia).
Why this is true
In placenta praevia the placenta implants over or near the internal os. As the lower segment forms and stretches in the third trimester, the inelastic placenta shears off its bed, opening maternal sinuses: bleeding is painless, bright red, recurrent, and the uterus stays soft because nothing irritates the myometrium. In abruption a normally sited placenta separates early, usually from vasospastic disease such as pre-eclampsia; blood tracks into the myometrium and behind the placenta, so the uterus becomes tense and tender, much of the bleed may be concealed, and placental thromboplastin release can trigger DIC.
Key points
Placenta praevia vs abruptio placentae
| Feature | Placenta praevia | Abruptio placentae |
|---|---|---|
| Pain | Painless | Painful |
| Bleeding | Revealed, bright red, recurrent | Revealed, concealed or mixed; dark |
| Uterus | Soft, non-tender | Tense, tender, woody hard |
| Fetal parts / lie | Easily felt; malpresentation | Difficult to feel |
| Fetal heart | Usually normal | Often distressed or absent |
| Shock | Proportional to visible loss | Out of proportion to visible loss |
| Key association | Previous caesarean, multiparity | Hypertension, trauma |
Common traps
- Shock out of proportion to the visible bleeding points to abruption with concealed haemorrhage.
- A 'warning haemorrhage' in praevia is typically small; don't be falsely reassured by its size.
Clinical case
A 32-week primigravida with severe pre-eclampsia develops sudden abdominal pain and a small amount of dark vaginal bleeding. BP 90/60 mmHg, pulse 120/min, the uterus is tense and tender and the fetal heart is not heard.
High-yield
Painless + soft uterus = praevia (no PV exam; ultrasound). Painful + tense uterus + hypertension = abruption (watch for DIC).
Quick check
Q1.Which is contraindicated in a woman with suspected placenta praevia?
Q2.Commonest obstetric cause of DIC: