A 32-year-old woman presents with acute obstetric DIC following placental abruption. Which of the following is the most common cause of DIC in obstetric practice?

Explanation

## Most Common Cause of Obstetric DIC **Key Point:** Placental abruption is the most frequent obstetric cause of DIC, accounting for approximately 50% of all obstetric DIC cases. ### Pathophysiology of Placental Abruption–Induced DIC 1. Placental separation releases large amounts of **tissue factor (TF)** and **phospholipids** into maternal circulation 2. TF activates the extrinsic coagulation pathway (Factor VII → Factor X) 3. Massive thrombin generation leads to: - Consumption of platelets and clotting factors - Formation of fibrin clots in microvasculature - Secondary fibrinolysis with elevated D-dimer and FDP ### Obstetric Causes of DIC — Comparative Frequency | Cause | Frequency | Mechanism | |-------|-----------|----------| | **Placental abruption** | **~50%** | Tissue factor release | | Amniotic fluid embolism | ~10% | Amniotic fluid entry into maternal circulation | | HELLP syndrome | ~10% | Endothelial activation + microangiopathy | | Retained dead fetus | Rare | Tissue factor from necrotic tissue | **High-Yield:** In obstetric DIC, **platelet count drops rapidly** (often <50,000/μL) and **fibrinogen is markedly depleted** (<100 mg/dL), distinguishing it from other causes of coagulopathy. **Clinical Pearl:** Placental abruption DIC presents acutely with vaginal bleeding, abdominal pain, and signs of shock; laboratory findings show thrombocytopenia, prolonged PT/aPTT, elevated D-dimer, and low fibrinogen within hours. **Warning:** Do not confuse placental abruption with amniotic fluid embolism — AFE is rarer (~1 in 40,000 deliveries) and presents with sudden cardiovascular collapse and respiratory distress, not primarily bleeding.