Q. A 55-year-old man with a history of advanced pancreatic cancer comes to the emergency room with sudden-onset bleeding from the venipuncture site and a rash over his trunk and extremities. His temperature is 100°F (37.78°C), heart rate is 102/min, respiratory rate is 18/minute, and blood pressure is 90/70 mm of Hg. He appears acutely ill. On physical examination, he has scleral icterus and extensive petechiae over the entire trunk and extremities. Hepatosplenomegaly present. Laboratory studies are shown below. A peripheral blood smear shows schistocytes. What is the best next step in diagnosing his condition?