A 32-year-old pregnant woman at 38 weeks gestation develops sudden hypotension, hypoxia, and disseminated intravascular coagulation during labor. Laboratory shows platelets 40,000/µL, PT and aPTT prolonged, fibrinogen 80 mg/dL, and elevated D-dimer. Which pathophysiological mechanism is most directly responsible?

• A Fetal squamous cells and mucin activating the intrinsic coagulation cascade
• B Massive release of tissue factor from decidual cells into maternal circulation ✓
• C Placental secretion of plasminogen activator inhibitor causing hyperfibrinolysis
• D Maternal antiplatelet antibodies crossing the placenta

Explanation

Amniotic fluid embolism triggers DIC through massive entry of tissue factor-rich amniotic fluid into maternal venous sinuses. Tissue factor activates the extrinsic coagulation cascade, generating widespread thrombin and microvascular thrombosis, followed by consumptive coagulopathy. While fetal squamous cells are found in pulmonary vasculature, they are not the primary trigger. This is distinct from placental abruption where decidual thromboplastin (tissue factor) also enters circulation.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.