Association between bariatric surgery preoperative chemoprophylaxis and postoperative bleeding

Background Use of chemoprophylaxis for prevention of venous thromboembolism (VTE) after bariatric surgery is a generally accepted principle; however, the optimal strategy in terms of medication type and pre- and postoperative dosing is uncertain. In our healthcare system, four hospitals performed bariatric surgery and utilized differing protocols for VTE prophylaxis. The analysis sought to evaluate the association of differing prophylaxis strategies on bleeding and VTE occurrence. Methods Adult patients who underwent laparoscopic sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) from 2018 to 2021 at four hospitals were studied. Patients were grouped by whether or not they received preoperative chemoprophylaxis. The primary outcome was postoperative bleeding, defined as requiring a blood transfusion or reoperation for bleeding within 30 days. Bivariate analyses were performed with Chi-square and Wilcoxon Rank tests where applicable. Multivariate logistic regression was performed for the outcome of postoperative bleeding. Results A total of 2145 bariatric surgeries were evaluated (33.6% RYGB, 66.4% SG). Among 1712 patients who underwent surgery at Hospitals A, B, and C, 93.1% received preoperative VTE prophylaxis, compared with 1 patient (0.1%) among 433 patients operated on at Hospital D. Postoperative bleeding occurred more frequently in patients who received preoperative VTE prophylaxis versus those who did not (3.7% vs 1.1%; p < 0.01). After multivariable regression analysis, only RYGB (OR 3.59; p < 0.01) and preoperative VTE prophylaxis (OR 3.54; p = 0.02) were significantly associated with postoperative bleeding. Rates of VTE for patients receiving preoperative VTE prophylaxis or no prophylaxis were not significantly different (0.6% vs. 0.2%; p = 0.26). Discussion Preoperative VTE prophylaxis prior to bariatric surgery was associated with postoperative bleeding without differences in VTE occurrence. These results call into question the routine use of VTE chemoprophylaxis for all patients undergoing bariatric surgery and favor selective usage.