The effect of postoperative enoxaparin on risk for reoperative hematoma.

Background: The risk of postoperative bleeding is the chief concern expressed by plastic surgeons who do not use pharmacologic prophylaxis against venous thromboembolism. The Plastic Surgery Foundation-funded Venous Thromboembolism Prevention Study examined whether receipt of postoperative enoxaparin prophylaxis changed 60-day reoperative hematoma rates.

Methods: In 2009, the study's network sites uniformly adopted a "best practice" clinical protocol to provide postoperative enoxaparin to adult plastic surgery patients at risk for perioperative venous thromboembolism. Historical control patients (2006 to 2008) received no chemoprophylaxis for 60 days after surgery. Retrospective chart review identified demographic and surgery-specific risk factors that potentially contributed to bleeding risk. The primary study outcome was 60-day reoperative hematoma. Stratified analyses examined reoperative hematoma in the overall population and among high-risk patients. Multivariable logistic regression controlled for identified confounders.

Results: Complete data were available for 3681 patients (2114 controls and 1567 enoxaparin patients). Overall, postoperative enoxaparin did not change the reoperative hematoma rate when compared with controls (3.38 percent versus 2.65 percent, p = 0.169). Similar results were seen in subgroup analyses for breast reconstruction (5.25 percent versus 4.21 percent, p = 0.737), breast reduction (7.04 percent versus 8.29 percent, p = 0.194), and nonbreast plastic surgery (2.20 percent versus 1.46 percent, p = 0.465). In the regression model, independent predictors of reoperative hematoma included breast surgery, microsurgical procedure, and post-bariatric surgery body contouring. Receipt of postoperative enoxaparin was not an independent predictor (odds ratio, 1.16; 95 percent CI, 0.77 to 1.76).

Conclusion: Postoperative enoxaparin does not produce a clinically relevant or statistically significant increase in observed rates of reoperative hematoma.

Clinical Question/level Of Evidence: Risk: II.