Differential diagnoses associated with coagulation assay results
| Prolonged prothrombin time (PT), normal activated partial thromboplastin time (aPTT) |
| Factor VII deficiency or factor VII inhibitor |
| Liver disease |
| Vitamin K deficiency |
| Warfarin use |
| Disseminated intravascular coagulation |
| Normal PT, prolonged aPTT |
| Deficiency of intrinsic pathway factors (VIII, IX, XI, XII) or inhibitors of these clotting factors |
| von Willebrand disease (if factor VIII is very low) Heparin use |
| Lupus anticoagulant (usually associated with thrombosis instead of bleeding) |
| Prolonged PT and aPTT |
| Deficiency of common pathway factors (II, V, X, or fibrinogen) |
| Severe liver disease |
| Vitamin K deficiency |
| Warfarin use |
| Disseminated intravascular coagulation |
| Heparin overdose |
| Normal PT and aPTT with bleeding |
| Platelet dysfunction (acquired or congenital) |
| von Willebrand disease (if factor VIII is mildly decreased) |
| Scurvy |
| Ehlers-Danlos syndrome |
| Hereditary hemorrhagic telangiectasia |
| Factor XIII deficiency |
| Hyperfibrinolysis |