It usually follows injury but occurs mainly in patients with a predisposition to hemorrhage such as those being treated with warfarin (or other anticoagulants) and patients with hemophilia. It can be associated with knee joint arthroplasty. It has also been reported as a part of hemorrhagic syndrome in the Crimean-Congo Hemorrhagic Fever, suggesting a viral cause to the bleeding in a joint space.
Hemarthrosis
Thrombophlebitis
Varicose veins
Phlebitis
Hemoperitoneum
Pulmonary hematoma
Retroperitoneal bleeding
Orthostatic purpura