Comparing venous thromboembolism (VTE) prophylaxis and bleeding risks: low molecular weight heparin vs. unfractionated heparin in open repairs of large hernias.

BACKGROUND

Venous thromboembolism (VTE) remains a major cause of postoperative morbidity and mortality in surgical patients undergoing open large abdominal wall hernia repairs. Uncertainty persists about whether low molecular weight heparin (LMWH) or unfractionated heparin (UFH) provides superior protection against VTEs without increasing bleeding risk. We sought to compare efficacy.

METHODS

We conducted a retrospective cohort study of adults undergoing open large abdominal wall hernia repairs at a single institution from 2019 to 2025. Patients received either LMWH or UFH for VTE prophylaxis. The primary endpoint was VTE within 30 days of surgery. Secondary endpoints included bleeding complications (hematomas, transfusion requirements, and reoperations for bleeding). Multivariable logistic regression was performed to assess independent risk factors for VTE and bleeding complications.

RESULTS

A total of 309 patients were included in this study: 156 patients received LMWH and 153 patients received UFH for VTE prophylaxis. The mean patient age was 59.0 ± 12.6 years, mean BMI was 34.5 ± 7.7 kg/m2, and median hernia area was 150 cm2 [91-238]. VTEs occurred in five patients (3.2%) in the LMWH group versus two patients (1.3%) in the UFH group (p = 0.45). Twelve patients in both the LMWH and UFH groups required a blood transfusion postoperatively and five patients in each group required reoperation for hematoma or bleeding (p > 0.99). Longer operative time was associated with development of a VTE (OR 1.81, 95% CI 1.24-2.76). Longer operative time (OR 1.58, 95% CI 1.25-2.04) and ASA class (OR 6.36, 95% CI 1.80-27.27) were associated with a bleeding complication (either blood transfusion or reoperation for bleeding).

CONCLUSIONS

In patients undergoing open large abdominal wall hernia repairs, LMWH and UFH demonstrated similar rates of VTEs and bleeding complications. These findings suggest that either agent is reasonable for prophylaxis in this population, and selection may be guided by patient-specific factors or institutional protocols.