Acquired Factor V Inhibitor in a Patient with a Mechanical Aortic Valve under Warfarin Therapy

Abstract

An 84-year-old woman under warfarin therapy, who had undergone mechanical valve replacement 29 months previously, developed coagulation abnormalities after antibiotic treatment for pyelonephritis. Laboratory findings included PT at 47.6 sec, activated thromboplastin time (APTT) at 147 sec, factor V (FV) activity of 4% and FV inhibitor of 8 BU. Although overt bleeding was not observed, administration of prednisolone was started. Her coagulation abnormalities were rapidly normalized. It was later determined that the patient had received bovine thrombin at surgery. The presence of a FV inhibitor should be considered in the differential diagnosis in patients demonstrating an unexpected prolongation of PT under warfarin therapy following surgery.

Acquired Factor V Inhibitor Developing After Percutaneous Ethanol Injection Therapy for Hepatocellular Carcinoma

“…Possible pathogenic mechanism of factor V inhibitors. In addition to the possibilities reported previously [2][3][4][5]12], ethanol in this report was described as an intrinsic causative agent.…”

“…The following examination revealed factor V inhibitor and their relation to percutaneous ethanol injection therapy (PEIT) for hepatocellular carcinoma (HCC). Factor V inhibitor has been reported in various diseases and in conditions related to medical procedures, especially in using bovine thrombin [2][3][4][5]. However, there is no report concerning factor V inhibitor caused by PEIT that is considered to be relatively safe among invasive therapies for HCC [6,7].…”

Acquired Factor V Inhibitor Developing after Treatment with Dabigatran Etexilate Methanesulfonate: A Case Report and Review of the Literature

“…There have been 2 reported cases of AFVI after treatment with warfarin [2,10], and it is considered that careful follow-up with periodic measurement of not only the blood coagulability, but also the factor V activity and factor V inhibitor is necessary in the future.…”

Acquired factor V inhibitor in a woman following aortic aneurysm surgery

“…The spectrum of clinical manifestations of this inhibitor ranges from mild to life-threatening bleeding [2]. The known risk factors for acquired FV inhibitor are multiple blood transfusions, trauma and surgery [4,5], use of antibiotics [5], autoimmune disorders [6], malignancy [7,8], hepatic disorders [8] and bovine thrombin exposure [9]. We present here a female patient who developed FV inhibitor following emergency aortic aneurysm surgery.…”

“…To our knowledge, no similar cases have been reported yet. We excluded bovine thrombin as the cause of acquired FV inhibitor [9], because it was not used during surgery. Moreover, as immediately after surgery methyloprednisolone was abruptly discontinued, it could contribute to the generation of FV inhibitor [6].…”