Bleeding Disorders: Coagulation Pathway Defects
Start with the big picture
The bleeding pattern offers an initial clue: coagulation factor defects commonly cause deep-tissue hematomas, joint bleeding, or delayed bleeding after trauma or surgery. Screening tests help localize the problem: aPTT evaluates intrinsic and common pathways, while PT/INR evaluates extrinsic and common pathways; platelet count and bleeding time are typically normal in isolated factor deficiencies. The topic compares inherited deficiencies, including hemophilias A, B, and C, with acquired problems such as vitamin K deficiency, liver disease, and DIC. It also introduces von Willebrand disease, factor XII deficiency, and Factor V Leiden as important distinctions. Mixing studies help assess whether an abnormal result reflects a factor deficiency or an inhibitor.
What you'll learn
- Distinguish typical bleeding patterns of coagulation defects from platelet-related bleeding.
- Relate aPTT and PT/INR results to the pathways they assess.
- Compare major inherited and acquired coagulation disorders using their characteristic laboratory patterns.
- Explain how mixing studies help distinguish factor deficiencies from inhibitors.
- Recognize selected conditions that complicate interpretation, including factor XII deficiency and Factor V Leiden.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
