Placental abruption

Aetiopathogenesis

Risk factors and key findings

• Cardinal finding: painful bleeding with a hard, tender uterus and a pathological CTG.
• The dangerous variant is concealed bleeding with no visible loss — the shock does not match what you can see.
• Risk factors: hypertension and pre-eclampsia, trauma, smoking and cocaine, ruptured membranes, polyhydramnios, previous abruption.
• Ultrasound signs: a hypoechoic mass between placenta and uterine wall, an undulating or sunken placental contour; importantly a normal scan does not exclude abruption.

Clinical features

Presentation

• The cardinal features are continuous pain, a board-like tender uterus and usually dark vaginal bleeding.
• In some cases the bleeding is concealed, because the haematoma collects behind the placenta — the loss is then underestimated.
• The CTG typically shows reduced variability, variable or late decelerations, progressing to bradycardia.

Complications

• The feared ones are intrauterine death and disseminated intravascular coagulation.
• The Couvelaire uterus denotes bleeding into the uterine muscle with blue-violet mottling (uteroplacental apoplexy).
• Further consequences are acute kidney injury, shock and postpartum haemorrhage.

Diagnosis

Ultrasound

• You may see a hypoechoic or heterogeneous mass between placenta and uterine wall, and a wavy, sunken placental contour.
• What matters: a normal scan does not exclude abruption.
• Fresh haematomas can look isoechoic to the placenta and so be missed.
• The diagnosis is therefore primarily clinical.

Typical imaging findings

• Ultrasound: Between the placenta and the uterine wall a hypoechoic to mixed-echogenic area lifts the placenta marginally off the wall. The placenta appears thickened at this point; the measurement records the extent of the haematoma.
• Ultrasound: Beside the gestational sac lies a crescent-shaped hypoechoic zone lifting the chorion off the uterine wall. The sac itself is normally configured; calipers record the extent of the bleed.

Keep learning in the app

Further reading (selection)

1. StatPearls: Placental Abruption (NCBI Bookshelf)
2. DocCheck Flexikon, Vorzeitige Plazentalösung

Cross-references