Increased bleeding risk with enoxaparin venothromboembolism prophylaxis compared with heparin in patients undergoing bariatric surgery

Background Perioperative venothromboembolism (VTE) chemoprophylaxis is an established tenant of bariatric surgery; however, there is little comparative data to guide medication choice. The objective of this study was to determine if a change in VTE prophylaxis from heparin to enoxaparin was associated with differing rates of postoperative bleeding and VTE occurrence after bariatric surgery. Methods This retrospective cohort study included patients 18 years or older who underwent primary bariatric surgery (sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB)) at a single institution between March 2012 and December 2021. Subcutaneous unfractionated heparin was utilized for VTE prophylaxis from March 2012 through February 2018 and then enoxaparin was used from March 2018 through December 2021. Postoperative bleeding was defined as requiring a blood transfusion or reoperation for bleeding within 30 days of surgery. Chi-square test was used to test for differences between groups. Results There were 2159 patients who underwent bariatric surgery with 1324 (61.3%) patients in the heparin group and 835 (38.7%) in the enoxaparin group. Overall, 1,503 (69.6%) patients underwent SG and 656 (30.4%) RYGB. There was no difference in the ratio of SG to RYGB between the heparin and enoxaparin groups. Most patients were female (n = 1709, 79.2%) with a median age of 43.2 years (interquartile range (IQR): 35.6–52.2), and median BMI of 44.9 (IQR: 40.9–50.5). Overall postoperative bleeding occurred more frequently in the enoxaparin group (n = 26, 3.1%) compared with the heparin group (n = 12, 0.9%) (p < 0.01). Additionally, reoperation for bleeding was more frequent with enoxaparin (enoxaparin 0.8% vs. heparin 0.2%, p = 0.04). There was no difference in VTE occurrence between the two groups (heparin: n = 14, 1.1%, enoxaparin: n = 7, 0.8% (p = 0.61)). Conclusions An institutional change from heparin to enoxaparin for bariatric surgery perioperative VTE prophylaxis was associated with a significant increase in postoperative bleeding, with no difference in VTE complications.