What is the likely diagnosis for an 8-month-old male presenting with hemarthrosis and hematuria?

The most likely diagnosis for an 8-month-old male presenting with hemarthrosis (bleeding into the joints) and hematuria (blood in the urine) is hemophilia. This hereditary bleeding disorder occurs due to a deficiency in specific clotting factors—most commonly factor VIII in hemophilia A and factor IX in hemophilia B. The presentation of joint bleeding and bleeding in urine aligns well with hemophilia, as these patients typically demonstrate a tendency for spontaneous bleeding after minor injuries, and they can have bleeding episodes without any trauma.

Infants and young children may present with bleeding symptoms as their physical activity increases, and in hemophilia, the defect lies in the body's ability to form a stable clot, leading to the observed symptoms. Characteristically, hemophilia often presents during infancy or early childhood, making it a more common diagnosis in this age group compared to other disorders.

Von Willebrand disease, while it also can cause bleeding symptoms, typically presents with mucocutaneous bleeding rather than hemarthrosis, making it less likely in this case. Thrombocytopenia generally presents with petechiae and easy bruising rather than significant hemarthrosis. Vitamin K deficiency can lead to a bleeding diathesis but