[A rare hemostatic disorder: pseudo von Willebrand's disease]

A case of pseudo von Willebrand's disease occurring in a 26 year old pregnant woman is reported. The diagnosis was made during the 33rd week of pregnancy. The patient had excessive bleeding of minor wounds, and biological tests revealed a bleeding time exceeding 20 min, a greatly reduced level of Rco fraction of von Willebrand's factor (27%), the absence of high molecular weight von Willebrand's factor multimers, and a greatly increased platelet aggregation in small doses of ristocetin. The patient was allowed to give birth by the vaginal route, receiving 30 IU.kg-1 highly purified concentrated factor VIII, once cervical dilatation was complete. Uterine revision was carried out for safety's sake because of prolonged post-partum bleeding. Two red cell packs were transfused as haemoglobin concentration decreased from 106 g.l-1 to 80 g.l-1. The newborn also presented with biological signs of pseudo von Willebrand's disease, with a bleeding time exceeding 15 min, hypothrombocytopaenia, and a level of Rco fraction of von Willebrand's factor of 9%. Preoperative assessment should always include an investigation of primary haemostatic mechanisms. In case of pseudo von Willebrand's disease, platelet transfusion combined or not with the transfusion of highly purified factor VIII seems to be useful. Investigation of other family members for a pseudo von Willebrand's disease trait is essential.