Coagulation disorders can be congenital or acquired. Congenital disorders include hemophilia A which is a factor VIII deficiency and hemophilia B which is a factor IX deficiency. Von Willebrand disease is the most common inherited bleeding disorder caused by a defect in von Willebrand factor. Acquired coagulation disorders result from vitamin K deficiency, liver disease, or disseminated intravascular coagulation. Screening tests for coagulation disorders include platelet count, prothrombin time, and activated partial thromboplastin time.