## Why 5–7 days before surgery; resume 24–48 hours post-operatively once hemostasis is adequate is right Aspirin irreversibly acetylates COX-1 in platelets, blocking thromboxane A2 synthesis and impairing aggregation. Because platelets are anucleate (lack a nucleus), they cannot synthesize new COX-1 enzyme; therefore, the antiplatelet effect persists for the entire platelet lifespan (~7–10 days). To achieve adequate platelet recovery before major elective surgery (high bleeding risk procedures), aspirin must be stopped 5–7 days preoperatively. This allows sufficient time for new, uninhibited platelets to be generated from bone marrow. Resumption 24–48 hours post-operatively is safe once hemostasis is established, balancing thrombotic and hemorrhagic risk. This is the standard perioperative management guideline in KD Tripathi 9e Ch 44. ## Why each distractor is wrong - **2–3 days before surgery; resume immediately post-operatively**: 2–3 days is insufficient for platelet turnover; many inhibited platelets would still circulate at surgery, increasing bleeding risk. Immediate post-operative resumption is premature and unsafe. - **10–14 days before surgery; resume 5–7 days post-operatively**: Unnecessarily prolonged preoperative discontinuation increases thrombotic risk in a post-MI patient. Delayed post-operative resumption is overly cautious and contradicts standard practice. - **1 day before surgery; resume 12–24 hours post-operatively**: 1 day is far too short; the majority of inhibited platelets remain in circulation, resulting in severe perioperative bleeding risk. This ignores the 7–10 day platelet lifespan. **High-Yield:** Aspirin's irreversible COX-1 inhibition + platelet anucleacy = effect lasts platelet lifespan → stop 5–7 days pre-op, resume 24–48h post-op. [cite: KD Tripathi 9e Ch 44]
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