A complication associated with polycythemia due to hyperviscosity is which of the following?

• A. Thrombosis
• B. Cardiomyopathy
• C. Pulmonary edema
• D. Disseminated intravascular coagulation (DIC)

Answer: (A)

When hematocrit is high, blood becomes more viscous, which slows flow, especially in the microcirculation. This sluggish flow promotes stasis and activates coagulation pathways, making clot formation more likely in both arteries and veins. That combination—hyperviscosity leading to impaired perfusion and increased thrombotic risk—is the hallmark complication of polycythemia related to the thickened blood, so thrombosis is the best answer. While polycythemia can strain the heart and, in some cases, contribute to edema, and while DIC is a separate coagulopathy, they are not the classic hyperviscosity-related complication.