Postoperative bleeding in an elderly patient from acquired factor V inhibitor: rapid response to immunosuppressive therapy.

Acquired factor V inhibitor is a rare but potentially life-threatening hemorrhagic disorder caused by the development of autoantibodies directed against coagulation factor V. The management of acute bleeding and inhibitor eradication is the mainstay of the treatment. The authors report a case of a 79-year-old man who underwent right hip arthroplasty and postoperatively, when on Coumadin for deep venous thrombosis prophylaxis, developed bleeding from the surgical site with a hematoma and abnormal coagulation parameters. Further workup revealed an acquired factor V inhibitor. The approach to treat this rare and challenging disorder is discussed. The patient responded rapidly with disappearance of factor V inhibitor titers after initiation of treatment with rituximab, prednisone and cyclophosphamide.