Ideally, a collagen binding assay (CBA) should be collected with a von Willebrands disease screen.
Please include any relevant bleeding history.

There is good evidence in place that an optimized VWF:CB assay can significantly reduce the diagnostic error rate otherwise arising from the use of a test panel restricted to including the VWF:RCo assay as the sole functional VWF assay. [Results of a recent multilaboratory survey indicate that laboratories not performing CBA testing have a 6-fold higher error rate for identification of VWD type 1 and are 10 times more likely to misclassify nonpathologic samples as VWD.] Nevertheless, the VWF:CB assay should not be used to wholly replace the VWF:RCo assay in phenotypic testing but rather as a supplementary assay. However, the VWF:CB assay can be used to partly replace the VWF:RCo assay in some "screening" applications and can also be used to abrogate the need to perform routine VWF:multimers in most test cases. As with the VWF:Ag and VWF:RCo assays, blood group–specific reference intervals may be useful for interpretation of VWF:CB results.