Placental Abruption

A placental abruption can become life-threatening before the amount of blood on a pad looks alarming. Blood may collect behind the placenta rather than exit through the vagina, while the pregnant person develops shock and the fetus loses placental oxygenation. Treat the haemorrhage, fetal compromise and risk of coagulopathy as parallel problems. The process begins when maternal decidual vessels rupture. A retroplacental haematoma then shears the placenta away from the uterine wall. Placental and decidual tissue factor enters the maternal circulation, producing rapid thrombin generation and consumption of fibrinogen and other clotting factors. This is why a patient with abruption can develop disseminated intravascular coagulation before measured vaginal blood loss appears large. A patient involved in a motor vehicle collision may have little external bleeding but a persistently firm, tender uterus and a prolonged fetal deceleration. That combination demands emergency assessment even if the blood pressure is initially normal.