Transient and Spontaneous Idiopathic Factor V Inhibitor

We present the case of a 70-year-old woman found to have a prothrombin time (PT) of 26.8 seconds (s) and an activated partial thromboplastin time (PTT) of 71 s prior to an elective endoscopic retrograde cholangiopancreatography for symptomatic choledocholithiasis. She had no personal or family history of bleeding, thrombosis, autoimmune diseases, miscarriages, recent surgery or antibiotic use, and was not anticoagulated. Laboratory studies revealed a hemoglobin of 11 g/dl, and normal leucocyte count, platelet count, serum protein immunoelectrophoresis, D-dimer, fibrinogen, lupus anticoagulants and anticardiolipin antibodies. PT and PTT mixing studies revealed an inhibitor of a coagulation factor in the common pathway. Factor assays II, VIII and IX, were normal. Factor VII and X, both more than 50%, were difficult to quantify secondary to an inhibitor effect in the system, with increasing activity after dilution. Factor V had 5% activity. Factor V inhibitor was 1.6 Bethesda Units. Prednisone 60 mg was started and the ERCP successfully performed with no bleeding complication. Within 6 months the PT, PTT and factor V activity normalized and prednisone was tapered off.