Surgical Duration and Risk of Venous Thromboembolism | Journal Scan

Study Questions:

What is the association between surgical duration and the incidence of venous thromboembolism (VTE)?


Using the American College of Surgery National Surgical Quality Improvement Program (NSQIP), a retrospective cohort of 1,432,855 patients undergoing surgery with general anesthesia at 315 hospitals across the United States was analyzed. The rates of deep vein thrombosis (DVT), pulmonary embolism (PE), and VTE within 30 days of an operation were assessed. Total time of anesthesia for each procedure was compared to the standard surgical duration based on Current Procedural Terminology codes to generate a z score. These results were divided into quintiles of surgical length for analysis. The association between surgical duration and the rate of DVT, PE, and VTE were assessed with logistic regression models adjusting for demographic, clinical, and comorbidity characteristics.


The overall rates of VTE, DVT, and PE were 0.96% (n = 13,809), 0.71% (n = 10,198), and 0.33% (n = 4,772), respectively. Patients undergoing surgical procedures in the middle quintile of duration experienced a VTE rate of 0.86% (95% confidence interval [CI], 0.83-0.90%). Surgical duration and VTE rate increased in a stepwise fashion for each surgical subspecialty (e.g., cardiothoracic, orthopedic, vascular). Patients undergoing the longest procedure durations were at increased risk of developing VTE (odds ratio [OR], 1.27; 95% CI, 1.21-1.34) compared to average length procedures. Patients undergoing the shortest procedure durations were at decreased risk of developing VTE (OR, 0.86; 95% CI, 0.83-0.88). Similar findings existed for both DVT and PE rates. A 1-hour increase in surgical duration was associated with an OR for VTE of 1.18 (95% CI, 1.06-1.30) for laparoscopic cholecystectomy, 1.18 (95% CI, 1.08-1.29) for laparoscopic appendectomy, and 1.26 (95% CI, 1.15-1.40) for laparoscopic gastric bypass.


The authors concluded that increasing surgical duration is directly associated with an increased risk of developing VTE.


This analysis describes the association of a prolonged procedure (and therefore immobilization) with the risk of VTE. The findings are convincing, given the size of the NSQIP database and consistency across multiple surgical subspecialties and commonly performed procedures. However, use of heparin agents for VTE prophylaxis, a prior history of VTE, and the presence of thrombophilia were not assessed and therefore not incorporated into the analysis. Whether these findings can be used to identify patients who require more intensive or longer-duration VTE prophylaxis still remains to be evaluated. Nevertheless, this study highlights the importance of addressing VTE prophylaxis in all patients undergoing surgical procedures.

Clinical Topics: Pulmonary Hypertension and Venous Thromboembolism, Vascular Medicine

Keywords: Anesthesia, General, Appendectomy, Cholecystectomy, Laparoscopic, Comorbidity, Current Procedural Terminology, Gastric Bypass, Laparoscopy, Pulmonary Embolism, Quality Improvement, United States, Venous Thromboembolism, Venous Thrombosis

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