Longer Surgeries Entail Higher Blood Clot Risk

The longer a surgical procedure takes to complete, the higher the risk of a life-threatening venous thromboembolism (VTE), according to a new study.

Researchers at Northwestern University (Chicago, IL, USA) conducted a large-scale, quantitative, retrospective cohort study involving 1,432,855 patients who had surgery under general anesthesia (GA) at 315 US hospitals to examine the association between surgical duration and the incidence of VTE. The main outcomes and measures included rates of deep vein thrombosis (DVT), pulmonary embolism (PE), and VTE within 30 days of the index operation.

Surgical duration was standardized and models were developed to examine the association, while adjusting for patient demographics, clinical characteristics, and co-morbidities.

The results showed that the overall VTE rate was 0.96%; the rates of DVT and PE were 0.71% and 0.33%, respectively. In the most common surgeries—including gall bladder removal, appendix removal, and gastric bypass for weight loss—every additional hour of surgery duration resulted in an 18%–26% increase in the risk of developing a clot. Compared with an average duration procedure, patients undergoing the longest procedures experienced a 1.27-fold increase in the odds of developing a VTE, while the shortest procedures demonstrated an odds ratio of 0.86. The study was published on December 3, 2104, in JAMA Surgery.

“Minute by minute, hour by hour, the trend is much more pervasive and consistent than any of us believed it could be. It was true across all procedures, specialties, and hospitals,” said senior author associate professor of surgery John Kim, MD. “There may be times when we have the option of cobbling together a couple of surgeries. If you know longer surgeries have a higher risk, depending on the variables, splitting up those surgeries may be the best option.”

VTE, DVT, and PE are lethal disorders that affect hospitalized and non-hospitalized patients, recur frequently, and are often overlooked. Evidence supports the use of heparin in people following surgery who have a high risk of thrombosis to reduce the risk of DVTs; however, the effect on PEs or overall mortality is not known. Complications of VTE include chronic thromboembolic pulmonary hypertension (CTPH) and the post-thrombotic syndrome (PTS).

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