Bleeding, Clotting, and Flap Failures: Management of Blood Thinners in Head & Neck Free Flaps

ABSTRACT Objective There is no consensus on blood thinner management in the perioperative period for head and neck free flap reconstructions. This study evaluated head and neck free flap outcomes in patients on baseline blood thinners, aspirin flap prophylaxis, and deep venous thrombosis (DVT) prophylaxis regimens. Methods Patients undergoing head and neck free flap reconstruction at a single tertiary, academic institution were included. Patients were grouped according to baseline blood thinners, aspirin flap prophylaxis, and DVT prophylaxis regimens. The primary outcome was overall complication rate, while secondary outcomes included flap compromise, flap failure, bleeding, venous thrombotic events, and arterial thrombotic events. Statistical analysis was performed with Fisher's exact test and risk ratio (RR) regression analysis, using propensity score‐adjusted models. Results Of 470 patients, 16.6% experienced postoperative complications. Longer preoperative holds (odds ratio [OR] = 1.81, p = 0.04) and delayed resumption of baseline blood thinners (OR = 1.56, p = 0.04) were associated with increased complication risk, particularly flap compromise. Unfractionated heparin was associated with higher complication rates compared to sequential compression devices (RR = 3.10, p = 0.018) and low molecular weight heparin (RR = 2.79, p < 0.001) for DVT prophylaxis. No other perioperative blood thinner regimens were significantly associated with postoperative complications. Conclusions Most regimens, including baseline blood thinners, aspirin flap prophylaxis, and DVT prophylaxis, can be managed safely in the perioperative period. However, unfractionated heparin was associated with higher complication rates than other DVT prophylaxis regimens. While baseline blood thinners did not increase most complications, prolonged preoperative holding and delayed resumption may jeopardize flap viability—highlighting a modifiable point of intervention. Level of Evidence 3.