[Utility of Global Coagulation Assays for Hemostasis Management in Hyperclearance-Type Autoimmune Acquired Coagulation Factor V Deficiency].

We report the case of an 80-year-old woman in which marked prolongation of prothrombin time (PT) and activated partial thromboplastin time (APTT) noted upon diagnosis of autoimmune hemolytic anemia revealed severe factor V (FV) deficiency. A mixing study showed a downward-convex pattern and the Bethesda assay for inhibitors was negative, which initially suggested congenital FV deficiency. Although the patient had concomitant early-stage esophageal cancer, infusions of fresh frozen plasma (FFP) failed to correct the coagulopathy, necessitating postponement of endoscopic therapy. Subsequently, a comprehensive evaluation by the Standardization Committee of the Japanese Ministry of Health, Labour and Welfare detected anti- FV IgG, establishing the diagnosis of hyperclearance-type autoimmune FV deficiency (AiFVD). Despite corticosteroid therapy, conventional coagulation screening test results remained markedly abnormal, complicating periprocedural management. In contrast, viscoelastic testing (VET) and thrombin generation testing (TGT), including ex vivo supplementation assays, indicated that adequate hemostasis could be achieved, allowing the endoscopic treatment to proceed safely. This case underscores that, even in FV deficiency with a negative inhibitor screen, testing for anti-FV IgG is essential for identifying hyperclearance-type AiFVD. Furthermore, ex vivo VET and TGT provided actionable assessments of hemostatic capacity and proved useful for guiding management in AiFVD.