A 63-year-old man with coronary artery disease who has recently undergone bypass surgery presents with dyspnea. Laboratory testing reveals a platelet count of 86,000 per cubic millimeter, as compared with 225,000 per cubic millimeter at the time of discharge nine days earlier. Findings on chest radiography are unremarkable; spiral computed tomography of the chest shows a pulmonary embolism. Heparin-induced thrombocytopenia is suspected. What diagnostic studies are warranted, and how should this patient be treated? A 63-year-old man who has recently undergone bypass surgery presents with dyspnea. His platelet count is 86,000 per cubic millimeter. Spiral CT of the chest shows a pulmonary embolism. Heparin-induced thrombocytopenia is suspected. What diagnostic studies are warranted, and how should this patient be treated? Foreword This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the authors' clinical recommendations. Stage A 63-year-old man with coronary artery disease who has recently undergone bypass surgery presents with dyspnea. Findings on physical examination are unremarkable. Laboratory testing reveals a platelet count of 86,000 per cubic millimeter, as compared with 225,000 per cubic millimeter at the time of discharge nine days earlier. The results of chest radiography are unremarkable; spiral computed tomography of the chest shows a pulmonary embolism. Heparin-induced thrombocytopenia is suspected. What diagnostic studies are warranted, and how should this patient be treated? The Clinical Problem Heparin-induced thrombocytopenia is a life-threatening disorder that follows exposure to unfractionated or (less commonly) low-molecular-weight . . .