Postoperative Prophylactic Anticoagulation in Flap Surgery: A Review of the Evidence and Challenging Common Beliefs

Postoperative anticoagulation is widely used in microsurgical flap reconstruction to reduce the risk of thrombosis and flap complications. However, their effectiveness and safety in relation to flap outcomes remain uncertain. This systematic review and meta-analysis evaluates the existing evidence on postoperative anticoagulant use in microsurgical flap reconstruction. A literature search was performed in PubMed database for studies published from 1995 until January 2025 that compared flap outcomes with postoperative prophylactic anticoagulation regimens in microsurgical flap procedures. Outcomes of interest included hematoma, complete flap failure, and reoperation. Relevant data were extracted and analyzed using meta-analytic techniques. In total, 11 studies were included in the final review and meta-analysis. Seven studies comparing patients who received postoperative anticoagulation with those who did not demonstrate a significantly higher rate of hematoma in the anticoagulated group (5.0% vs. 3.0%; p = 0.03). However, there were no significant differences in flap failure or reoperation rates. In subgroup analyses, only studies using UFH showed increased hematoma risk, whereas LMWH showed no significant effect. Four studies compared patients receiving postoperative anticoagulation plus aspirin with those receiving anticoagulation alone and found a higher reoperation rate when aspirin was added (17.5% vs. 10.0%; p < 0.01), with no significant differences in flap failure rates. Postoperative heparin increases the risk of hematoma without improving flap survival. Additionally, combining aspirin with LMWH may increase reoperation rates. These results suggest that routine anticoagulation may not benefit all patients and support a risk-based approach to postoperative management in microsurgical reconstruction.