Thromboprophylaxis After Bariatric Surgery: BJS Open | August 2026

Introduction:

Patients undergoing metabolic bariatric surgery are at risk for both venous thromboembolism (VTE) and postoperative bleeding. However, the optimal timing and duration of thromboprophylaxis remain uncertain. This large nationwide registry study evaluated the impact of different thromboprophylaxis strategies on thrombotic and bleeding outcomes.

Why was this study needed?

• Bariatric surgery patients have an increased risk of VTE due to obesity and surgery.
• Anticoagulation reduces thrombosis but may increase bleeding complications.
• Current recommendations regarding timing and duration of thromboprophylaxis are largely based on expert opinion.
• Considerable variation exists in clinical practice.
• High-quality real-world evidence is needed to optimize perioperative anticoagulation.

Results:

• Postoperative initiation of thromboprophylaxis significantly reduced intraoperative bleeding compared with preoperative administration, without increasing the risk of venous thromboembolism.
• The duration of thromboprophylaxis was not associated with significant differences in VTE or postoperative bleeding, suggesting that prolonged prophylaxis did not provide additional benefit in the overall population.
• Previous VTE, intraoperative bleeding, and prolonged operative time increased VTE risk, while older age, male sex, cardiovascular disease, and antidepressant use were associated with higher postoperative bleeding risk.

Clinical Impact:

This large registry study supports postoperative initiation of thromboprophylaxis as a safer strategy for most patients undergoing metabolic bariatric surgery by reducing bleeding without compromising thromboembolic protection. Duration of prophylaxis should be individualised according to patient-specific VTE risk factors rather than routinely prolonged.

Bottom Line:

Starting thromboprophylaxis after bariatric surgery reduces intraoperative bleeding without increasing venous thromboembolism. These findings support a risk-stratified approach to anticoagulation timing and duration rather than a universal extended prophylaxis strategy.