A 62-year-old woman presented to the emergency department with dyspnea, chest pain, and fever that developed a few hours earlier. The patient was in the hospital where she underwent total knee replacement surgery. She had been administered heparin for postoperative anticoagulation for 5 days when she developed these symptoms. On physical examination, a petechial rash was seen. Laboratory examination showed thrombocytopenia and prolonged bleeding time.
What’s the diagnosis?