The Impact of Obesity on Intraoperative Complications in Rectal Cancer

Abstract

Background: Obesity is a growing global health concern and poses significant challenges in rectal cancer surgery. Excess visceral fat can obscure surgical landmarks, complicate dissection, and increase the risk of intraoperative adverse events (iAEs). Despite these recognized difficulties, there is limited objective data quantifying the impact of obesity on intraoperative complications. This study utilizes the CLASSIntra classification system to assess the incidence and severity of iAEs in patients with obesity (BMI ≥ 30 kg/m2) undergoing rectal cancer resection. Methods: This retrospective cohort study reviewed patients undergoing rectal cancer resection between January 2014 and December 2023. Patients were stratified into groups by BMI (obese (BMI≥ 30 kg/m2) versus non-obese (BMI < 30 kg/m2)). The primary outcome was the incidence and severity of iAEs, graded using the CLASSIntra system. Secondary outcomes included conversion to open surgery, postoperative complications, ICU admissions, and overall length of stay. Results: There were 350 patients included (112 obese, 238 non-obese). There were significantly more iAEs in the obese group (40% vs. 26%, p = 0.010). Obesity was an independent predictor of intraoperative complications (OR 1.92, p = 0.010). Conversion to open surgery (27% vs. 40%, OR 2.30, p = 0.0100) and ICU readmission (50% vs. 31%, OR 2.35, p = 0.003) were significantly more common in patients with obesity. There were no significant differences in postoperative complication rates and hospital length of stay between groups. Conclusion: Obesity leads to a higher risk of intraoperative complications in rectal cancer surgery, increased conversion rates, and greater ICU resource utilisation. These findings highlight the technical challenges of rectal surgery in obese patients and emphasize the need for tailored preoperative planning, prehabilitation, and intraoperative strategies. Despite these intraoperative difficulties, structured postoperative care appears to mitigate differences in postoperative outcomes. Further research should explore preoperative interventions, such as weight optimization programs, to improve surgical outcomes in this high-risk population.