General Pathology USMLE Step 1 Practice Question

A 30-year-old woman experiences sudden severe dyspnea, hypotension (BP 80/50), and cyanosis during active labor. Minutes later, she develops profuse bleeding from intravenous sites and gingival oozing. Vital signs show tachycardia (HR 128/min), tachypnea (RR 22/min), and SpO2 88% on room air. Laboratory studies reveal thrombocytopenia (platelets 45,000/μL), prolonged PT (18 seconds) and PTT (52 seconds), and normal fibrinogen levels. She denies recent anticoagulant use. Which pathophysiologic mechanism most likely underlies this condition?