What findings are typically observed in laboratory results for von Willebrand's disease?

In von Willebrand's disease, the most commonly observed laboratory findings include a normal prothrombin time (PT) and an increased activated partial thromboplastin time (aPTT). This is due to the role of von Willebrand factor in stabilizing factor VIII in circulation; a deficiency or dysfunction of this factor leads to a reduction of factor VIII levels, thus prolonging the aPTT.

While the PT remains normal because it primarily assesses the extrinsic and common pathways of coagulation that are not significantly affected by von Willebrand factor, the aPTT is elongated due to the impaired function and stability of factor VIII. Additionally, bleeding time is typically prolonged in von Willebrand's disease because this condition affects platelet adhesion, which is crucial for effective primary hemostasis.

This understanding is essential for differentiating von Willebrand's disease from other bleeding disorders, as recognizing these specific laboratory findings can help guide diagnosis and management.