Diagnosis of von Willebrand Disease
Physical examination usually reveals nonspecific evidence of easy bruising and bleeding. The diagnosis of vWD depends in large part on laboratory findings.
Bleeding time (is prolonged)
Platelet aggregation test
Platelet count (may be low or normal)
Ristocetin cofactor test (the primary assay test used to diagnose von Willebrand disease)
Von Willebrand factor level (level is reduced)
Complete blood count (CBC), Prothrombin time (PT) and Activated partial thromboplastin time (aPTT) are important investigations that give clues.
The results of the following tests may also be altered:
Factor VIII level
Von Willebrand factor multimers (parts of the von Willebrand factor protein molecule)
Gene-based assays are highly specific.