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# vWD type I
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* vWD type I can be diagnosed in a patient with significant mucocutaneous bleeding, laboratory test results compatible with vWD type I, and a positive family history for vWD type I. These criteria may be impossible to satisfy in many patients for various reasons. Therefore, physicians must acknowledge this diagnostic uncertainty and should not deny patients treatment, especially when patients' laboratory test results are compatible with vWD type I and they have either a significant history of mucocutaneous bleeding or a positive family history for vWD type I.
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* A less common problem is the misdiagnosis of vWD type I in patients who actually have a qualitative defect. The results of screening tests recommended for patients with vWD type I often show proportionally decreased RCoF activity and vWF:Ag in patients with vWD type IIB, although classic teaching is that a discrepancy should exist between the two. In this scenario, ristocetin-induced platelet aggregation test results should demonstrate an exaggerated affinity of the mutant vWF for platelets in the presence of ristocetin.
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# vWD type II
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* Disproportionately low RCoF activity relative to vWF:Ag may reflect a decreased affinity of vWF for platelets. The most common cause of such loss of function is the absence of hemostatically effective large vWF multimers, characteristic of vWD type IIA. This subtype is diagnosed based on the combination of markedly reduced RCoF activity and compatible multimer gel analysis results.
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* In type IIB, brisk platelet agglutination occurs at low concentrations of ristocetin that have little or no effect on platelet-rich plasma from normal controls. Positive results from this test are found in only one other extremely rare disease, platelet-type or pseudo vWD, in which mutations in platelet GpIb cause a phenotype similar to that of vWD type IIB.
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* vWD type IIM (M for multimer) includes variants in which binding to platelets is impaired but the vWF multimer distribution is normal. Screening laboratory test findings are similar to those found in vWD type IIA, but multimer gel analysis results show that large multimers are present.
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* In vWD type IIN (N for Normandy), the platelet-dependent functions of vWF are preserved, but FVIII levels are low (often <10%). This condition is an autosomal mimic of hemophilia A, and a careful family history helps distinguish the two.
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* Multimeric examination of the vWF is particularly important in the diagnosis of type II vWD. Results from this laboratory test reveal the multimeric distribution of vWF, thus allowing classification of type II disease depending on the specific absence of large multimers (type IIB) or both intermediate and large (type IIA) multimers.
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# vWD type III
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* This is a recessive disorder in which vWF protein is virtually undetectable. The absence of vWF causes a secondary deficiency of FVIII and a subsequent severe combined defect in blood clotting and platelet adhesion.

* Results from screening assays show absent RCoF activity and vWF:Ag and a prolonged aPTT.