Plastic and reconstructive surgeons consistently create large, raw surfaces as part of their operative procedures. Thus, plastic & reconstructive surgery patients are among those at highest risk for anticoagulant-associated bleeding adverse drug events (ADEs). Our preliminary data has shown that a fixed, or "one size fits all" dose of enoxaparin, an anticoagulant, can allow a high proportion of patients to have appropriately thinned blood, measured by anti-Factor Xa (aFXa) levels. Patients with adequate aFXa levels are known to have significantly decreased venous thromboembolism risk (VTE), which is desirable. However, 30% of patients who receive fixed dose enoxaparin have blood that is too thin. Patients who are over-anticoagulated are significantly more likely to have ADEs including bleeding requiring return to the operating room, need for blood transfusion, or death. The optimal way to dose enoxaparin to minimize ADEs remains unknown. This study seeks to optimize both the safety and effectiveness of post-operative enoxaparin by comparing aFXa levels, bleeding events, and VTE events among plastic & reconstructive surgery patients randomized to receive two different enoxaparin dose regimens.