VWF and blood coagulation disease: In a study performed in 6 centers in the United States, among 232 women with PBAC scores of >100, a laboratory abnormality was found in 73.3%, including both white (68.1%) and black (91.9%) subjects; 6.0% had VWD, 56.0% had abnormal platelet aggregation tests, 4.7% had a non-VWD coagulation defect, and 6.5% had an abnormal PFA only.