Which test result is typically normal in a patient with classic von Willebrand's disease?

In classic von Willebrand's disease, the platelet count remains typically normal. This condition is primarily characterized by a deficiency or dysfunction of von Willebrand factor, which plays a crucial role in platelet adhesion and aggregation. However, the number of platelets itself, as counted in a complete blood count, does not change in this disorder.

Bleeding time is often prolonged due to the impaired function of platelets in hemostasis when von Willebrand factor is deficient. The activated partial thromboplastin time (aPTT) can also be prolonged depending on the severity of von Willebrand's disease because von Willebrand factor is important for protecting factor VIII from degradation. Lastly, both Factor VIII:C and von Willebrand’s factor levels are typically decreased in classic von Willebrand's disease, reflecting the underlying pathology.

Thus, in this context, the normal platelet count is a distinguishing feature that helps differentiate classic von Willebrand’s disease from other bleeding disorders that might present with thrombocytopenia or other abnormalities in blood parameters.