For von Willebrand disease, the following tests permit an accurate diagnosis:
|Factor VIII:C||This measures the amount of factor VIII clotting activity.|
|VWF: antigen||This measures the amount of von Willebrand factor.|
|Ristocetin cofactor activity||This measures how well the VWF works.|
|VWF multimers||This examines the structure of the VWF.|
|Platelet function tests||These measure how well the platelets work.|
For platelet function disorders, the following tests permit an accurate diagnosis:
|Bleeding time||This measures the length of time it takes for a simple cut to stop bleeding.|
|Platelet aggregation studies||These measure if there are abnormalities in the way platelets clump together.|
|Von Willebrand Factor studies||These find out if the Von Willebrand Factor protein is working normally and rule out this similar disorder as the cause of the bleeding.|
|Specialized tests||These determine the exact type of platelet function disorder.|
For hemophilia A and B, they will take a blood sample and do simple lab tests to measure the amount of factor VIII and factor IX in the blood.
Because the other clotting factor deficiencies are so rare, tests are first done to rule out von Willebrand disease, platelet function disorders, and hemophilia A and B as the cause of bleeding. If one of the rare factor deficiencies is suspected, a laboratory assay is done to measure the level of the specific clotting factor.
These tests are done in a lab which specializes in bleeding disorders. Most hemophilia/bleeding disorder clinics offer this service.
It is extremely important for a woman who suspects she has a bleeding disorder to go to a hemophilia / bleeding disorder clinic for testing. People at such a clinic know that tests often need to be repeated to get a correct diagnosis. This is because test results can be affected by:
- normal hormonal changes that happen during a woman’s monthly cycle
- recent use of aspirin or other pain-killers
- birth control pills, hormone therapy, pregnancy, breast feeding, or recent child birth
- strenuous exercise, stress or emotional upset just before having blood drawn
- variation in the lab technologist’s technique
- blood type (Women with blood type O have naturally lower levels of von Willebrand factor and factor VIII than women with blood types A, B or AB.).
Because of these testing difficulties, many women have been told they have no bleeding disorder when, in fact, they do.