Type IB von Willebrand's disease and pregnancy: comparison of analytical methods of von Willebrand factor for classification of von Willebrand's disease subtypes.

The clinical course and changes in von Willebrand factor (vWf), factor VIII and bleeding time during pregnancy are described in a patient with type IB von Willebrand's disease (vWD) in whom all vWf multimers were present in plasma with relatively reduced content of the high-molecular-weight multimers. At term, ristocetin cofactor was elevated to some extent (from the baseline value of 5 U/dl to 23 U/dl), but never normalized and below the level of vWf antigen (49 U/dl). Bleeding time remained prolonged. In addition, abnormal distribution in the multimer size of plasma vWf was never corrected. These findings contrast with favorable responses during pregnancy reported in type IA individuals. The patient was infused during labor with 400 ml of fresh frozen plasma, and blood loss was approximately 800 ml. Analytical techniques of vWf by crossed immunoelectrophoresis, gel filtration on Sepharose 2B and SDS-agarose gel electrophoresis for the classification of vWD subtypes were compared. Multimer analysis by SDS-agarose gel electrophoresis was needed for differentiation of type IB from type IIA vWD.