A 45-year-old woman undergoes preoperative screening before elective surgery. Laboratory studies reveal elevated aPTT (48 seconds) with normal PT (12 seconds), platelet count (245,000/μL), and fibrinogen (340 mg/dL). Mixing study with normal plasma shows persistent aPTT prolongation. She denies personal or family history of bleeding and takes no anticoagulants. Vital signs are stable: BP 128/82 mmHg, HR 76/min, RR 14/min, Temp 37°C. Which of the following is the most likely explanation?
- A)Factor XII deficiency
- B)Heparin contamination of sample
- C)Lupus anticoagulantGABARITO
- D)Factor V deficiency
- E)von Willebrand disease
Explicação
Lupus anticoagulant is an antiphospholipid antibody that prolongs aPTT in vitro but does NOT correct on mixing study (distinguishes from factor deficiency). Despite in vitro anticoagulation, patients are hypercoagulable and at risk for thrombosis. No bleeding ... Ver explicação completa e trilha adaptativa →