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Difficulty: MediumHemodynamic and Coagulation Processes

For each patient presenting with a distinct hemorrhagic or thrombotic disorder, select the primary underlying pathophysiologic mechanism.

  • A 32-year-old woman with a history of recurrent miscarriages presents with an unprovoked deep vein thrombosis. Labs show a prolonged aPTT that fails to correct with a mixing study.Circulating autoantibodies directed against phospholipid-protein complexes
  • A 45-year-old man with advanced chronic kidney disease presents with persistent oozing from a dental extraction site. Labs reveal a normal platelet count, PT, and aPTT, but a prolonged bleeding time.Accumulation of toxins causing defective platelet adhesion and aggregation
  • A 28-year-old woman develops severe postpartum hemorrhage, widespread petechiae, and acute kidney injury. Labs show thrombocytopenia, prolonged PT and aPTT, and an elevated D-dimer.Systemic coagulation activation leading to widespread consumption of clotting factors and platelets
  • A 15-year-old girl is evaluated for heavy menstrual bleeding and frequent epistaxis. Labs show a normal platelet count and PT, but a prolonged aPTT that corrects with a mixing study.Deficiency of a multimeric glycoprotein required for platelet adhesion and Factor VIII half-life stabilization

Answer

The presentations are matched as follows: Antiphospholipid syndrome is caused by circulating autoantibodies; uremic bleeding is due to toxin accumulation impairing platelets; DIC is characterized by systemic coagulation activation; and von Willebrand disease is caused by a deficiency of a multimeric glycoprotein.
Each clinical vignette highlights pathognomonic historical and laboratory findings that map to a unique hemostatic defect. Antiphospholipid syndrome involves autoantibodies; uremic bleeding involves toxin-induced acquired platelet dysfunction; DIC involves massive consumptive factor depletion; and von Willebrand disease involves a lack of the bridging glycoprotein required for both platelet adhesion and Factor VIII protection.

Step-by-Step Solution

1
Evaluate the patient with thrombosis, miscarriages, and a prolonged, non-correcting aPTT.
Identify this as antiphospholipid syndrome.
A non-correcting mixing study indicates an inhibitor, such as lupus anticoagulant, which targets phospholipid-protein complexes.
2
Assess the patient with advanced chronic kidney disease and isolated prolonged bleeding time.
Identify this as uremic platelet dysfunction.
Renal failure leads to the accumulation of uremic toxins that interfere with normal platelet adhesion and aggregation, leaving the absolute platelet count and secondary hemostasis intact.
3
Review the presentation of postpartum hemorrhage with thrombocytopenia, elevated D-dimer, and prolonged PT/aPTT.
Identify this as disseminated intravascular coagulation (DIC).
Obstetric emergencies can trigger massive systemic activation of the coagulation cascade, consuming clotting factors and generating fibrin degradation products.
4
Analyze the case of a teenager with mucosal bleeding and a prolonged, correcting aPTT.
Identify this as von Willebrand disease.
A correcting mixing study suggests a factor deficiency. A deficiency in von Willebrand factor (a multimeric glycoprotein) reduces Factor VIII half-life, explaining the isolated prolonged aPTT.

Key Concept

Identifying underlying mechanisms of coagulation disorders through distinct clinical and laboratory profiles.
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Topics

Hemodynamic and Coagulation Processes

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