Extended versus conventional thromboprophylaxis after major abdominal and pelvic surgery: Systematic review and meta-analysis of randomized clinical trials

Background: Venous thromboembolism, presenting as deep vein thrombosis or pulmonary embolism, can be associated with considerable morbidity after major abdominal and pelvic surgery. Perioperative thromboprophylaxis with low-molecular-weight heparin is well established, but the duration of treatment remains debated. We aimed to assess the efficacy and safety of extended (4-week) versus conventional (1-week) thromboprophylaxis with low-molecular-weight heparin in patients undergoing abdominopelvic surgery. Methods: Using MEDLINE databases (PubMed, EMBASE, and Web of Science), we conducted an electronic, systematic search of randomized controlled trials comparing post-operative extended versus conventional low-molecular-weight heparin on venous thromboembolism, deep vein thrombosis, and pulmonary embolism rates. Results: Four randomized controlled trials met the predefined criteria. Extended prophylaxis with low-molecular-weight heparin after major abdominal and pelvic surgery decreased rates of postoperative venous thromboembolism, deep vein thrombosis, and proximal deep vein thrombosis without increased postoperative bleeding. Numbers needed to treat to prevent venous thromboembolism, overall deep vein thrombosis, and proximal deep vein thrombosis were 14, 14, and 44, respectively. Rates of postoperative symptomatic PE were rare, and the incidence was similar in both groups. Conclusion: Extended prophylaxis with low-molecular-weight heparin is associated with a decrease in asymptomatic venous thromboembolism. There remains sparse evidence regarding its impact on pulmonary embolism because of the overall low incidence. Extended prophylaxis should be considered in high-risk patients.