Hemostasis and Coagulation Cascade

Which laboratory finding best distinguishes Hemophilia A from von Willebrand disease in a patient presenting with mucosal bleeding and a prolonged activated partial thromboplastin time (aPTT)?

A 38-year-old woman with a history of recurrent thrombosis is found to have a prolonged aPTT that does not correct with 1:1 mixing study. Which single laboratory result best distinguishes an antiphospholipid antibody from a Factor V inhibitor (acquired inhibitor)?

Which coagulation parameter best distinguishes Disseminated Intravascular Coagulation (DIC) from Vitamin K deficiency in a critically ill patient with prolonged PT and aPTT?

A 32-year-old woman presents to the emergency department with spontaneous bleeding from gums and petechial rash over lower limbs for 3 days. She denies any recent infections or medication use. On examination, she has severe thrombocytopenia (platelet count 8,000/µL). Coagulation studies show: PT 12 sec (normal), aPTT 32 sec (normal), bleeding time prolonged. Bone marrow examination reveals adequate megakaryocytes. What is the most likely diagnosis?

A 35-year-old woman presents to the emergency department with spontaneous bleeding from gums, petechiae on lower limbs, and a platelet count of 8,000/μL. Peripheral blood smear shows no schistocytes. PT and aPTT are normal. What is the most appropriate next step in management?