Approach to determining VWD subtype

Diagnosis of VWD includes both clinical and laboratory features. After determining whether VWD is present (refer to separate algorithm in UpToDate), one then determines the subtype, which has implications for management, as depicted here. Type 1 is the most common, affecting 75 to 85% of individuals. Type 2A affects approximately 10 to 15% of individuals and type 2B affects approximately 5%. Types 2M and 2N are less common, and type 3 is rare. The bleeding history, family history, and inheritance pattern are also important factors in making the diagnosis of VWD and in assigning the type. Screening may be performed by the primary clinician or hematologist. Secondary testing is generally done by the consulting hematologist or clinician with expertise in diagnosing VWD.