Minimally invasive colorectal surgery in the morbid obese: does size really matter?

Background: As obesity becomes more prevalent, it presents a technical challenge for minimally invasive colorectal resection surgery. Various studies have examined the clinical outcomes of obese surgical patients. However, morbidly obese patients (BMI ≥ 35) are becoming increasingly more common. This study aims to investigate the short-term surgical outcomes of morbidly obese patients undergoing minimal-invasive colorectal surgery and compare them with both obese (30 ≤ BMI < 35) and non-obese patients (BMI < 30).

Methods: Patients from three centres who received minimally invasive colorectal surgical resections between 2006 and 2016 were identified from prospectively collected databases. The baseline characteristics and surgical outcomes of morbidly obese, obese and non-obese patients were analysed.

Results: A total of 1386 patients were identified, 84 (6%) morbidly obese, 246 (18%) obese and 1056 (76%) non-obese. Patients' baseline characteristics were similar for age, operating surgeon, surgical approach but differed in terms of ASA grade and gender. There was no difference in conversion rate, length of stay, anastomotic leak rate and 30-day readmission, reoperation and mortality rates. Operation time and blood loss were different across the 3 groups (morbidly obese vs obese vs non-obese: 185 vs 188 vs 170 min, p = 0.000; 20 vs 20 vs 10 ml, p = 0.003). In patients with malignant disease there was no difference in lymph node yield or R0 clearance. Univariate and multivariate linear regression analysis showed that for every one-unit increase in BMI operative time increases by roughly 2 min (univariate 2.243, 95% CI 1.524-2.962; multivariate 2.295; 95% CI 1.554-3.036). Univariate and multivariate binary logistic regression analyses showed that BMI does not affect conversion or morbidity and mortality.

Conclusions: The increased technical difficulty encountered in obese and morbidly obese patients in minimally invasive colorectal surgery results in higher operative times and blood loss, although this is not clinically significant. However, conversion rate and post-operative short-term outcomes are similar between morbidly obese, obese and non-obese patients.