Bleeding disorders of unknown cause: A conglomeration of disorders with heterogeneous etiology

Patients with clinically significant bleeding, but with normal hemostatic investigations are identified as a distinct group known as "bleeding disorders of unknown cause" (BDUC). Though the clinical symptoms often resemble that of mild bleeding disorders (MBDs) with confirmed laboratory diagnosis, these patients have to go through multiple laboratory investigations only to end up in a diagnosis of exclusion i.e. BDUC. There are no standard protocols or general consensus on treatment of these patients, either for a generalized bleeding or prophylaxis prior to surgical procedures; patients are treated as per the physician perceptions or practices and many patients go untreated. Patients with BDUC are at increased risk of uncontrolled bleeding during trauma, surgery, and during delivery. Present review discusses the standard tests required for diagnosis of BDUC, type of bleeding, treatment modalities and future perspectives. Research should focus both on hemostatic, non-hemostatic and acquired factors contributing to bleeding. Evidence based diagnostic and treatment guidelines for this clinically mild group of patients are warranted for specific hemostatic interventions.