Postoperative Thromboprophylaxis After Bariatric Surgery

Quick Takes

  • The effectiveness of extending postoperative rivaroxaban thromboprophylaxis after bariatric surgery out to 28 days, versus 7 days, was investigated.
  • In this modified intention-to-treat population that included patients undergoing sleeve gastrectomy, Roux-en-Y, and revision bariatric surgery, reported incidence of thrombosis was low, suggesting rivaroxaban 10 mg daily is effective in preventing postoperative venous thrombosis.
  • Adverse bleeding events were more prevalent with the longer (28-day) postoperative exposure to anticoagulation, but in this study, that difference did not reach statistical significance.

Study Questions:

Does longer duration of postoperative venous thrombosis prophylaxis (28 days vs. 7 days) affect risk of postoperative venous thrombosis among obese patients undergoing bariatric surgery?


Patients ≥18 years of age with body mass index ≥35 kg/m2, scheduled to undergo bariatric surgery at one of three bariatric centers in Switzerland between July 1, 2018 and June 30, 2021, were eligible to participate.

On postoperative day 1, all were assigned to receive rivaroxaban 10 mg daily, randomized to a duration of 7 days versus 28 days. The primary composite outcome was: 1) any deep vein thrombus (proximal or distal), or 2) pulmonary embolus (confirmed by computed tomography or VQ scan if clinically suspicious signs or symptoms were noted during hospitalization or follow-up visits). All subjects received bilateral lower extremity ultrasound to exclude deep vein thrombosis (DVT) 28-30 days after surgery, and a safety assessment by telephone on postoperative day 35. Secondary outcomes included 28-day postoperative all-cause mortality. The main safety outcome was major bleeding (defined as any event requiring blood transfusion or decrease in hemoglobin of ≥2 g/dL).


Among 300 enrolled patients, 272 were randomized, 3 were excluded due to postoperative bleeding prior to randomization, and 12 dropped out after randomization (5 in short and 7 in long prophylaxis groups). The remaining modified intention to treat (mITT) population consisted of 129 patients in the short and 128 patients in the long prophylaxis arms. Among the mITT population, the primary outcome (asymptomatic DVT) was observed in one patient in the long prophylaxis group and 0 patients in the short prophylaxis group (no statistical difference).

Serious adverse events occurred more frequently among patients in the long versus short prophylaxis group (in 12 [8.9%] vs. 6 [4.5%] patients) but that difference did not reach statistical significance (p = 0.80). Adverse events leading to premature discontinuation of anticoagulation were also more prevalent in the long versus short prophylaxis group (in 9 vs. 3 patients), but that difference likewise did not reach statistical significance (p = 0.50).


Among patients undergoing bariatric procedures, rivaroxaban 10 mg daily for 7 days versus 28 days produced no significanct difference in incidence of thrombotic events within the first month after surgery. Adverse events were more common in the longer period of prophylaxis, although in this study population, that difference did not differ statistically.


The apparent low incidence of postoperative venous thrombosis events (1 among 257 in the mITT population) indicates that rivaroxaban 10 mg daily is effective against postoperative venous thrombosis, but also raises the possibility that the study was underpowered to detect a difference in effectiveness and adverse events with a 7-day versus 28-day course.

Clinical Topics: Anticoagulation Management, Diabetes and Cardiometabolic Disease, Noninvasive Imaging, Prevention, Pulmonary Hypertension and Venous Thromboembolism, Vascular Medicine, Anticoagulation Management and Venothromboembolism, Echocardiography/Ultrasound

Keywords: Anticoagulants, Bariatric Surgery, Body Mass Index, Diagnostic Imaging, Gastrectomy, Gastric Bypass, Hemoglobins, Hemorrhage, Metabolic Syndrome, Obesity, Primary Prevention, Pulmonary Embolism, Rivaroxaban, Ultrasonography, Vascular Diseases, Venous Thromboembolism, Venous Thrombosis

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