Robotic-assisted versus laparoscopic rectal surgery in obese and morbidly obese patients: ACS-NSQIP analysis

Laparoscopic rectal surgery within the confines of a narrow pelvis may be associated with a high rate of open conversion. In the obese and morbidly obese patient, the complexity of laparoscopic surgery increases substantially. Robotic technology is known to reduce the risk of conversion, but it is unclear if it can overcome the technical challenges associated with obesity. The ACS NSQIP database was used to identify obese patients who underwent elective laparoscopic or robotic-assisted rectal resection from 2015 to 2016. Obesity was defined as a body mass index (BMI) greater than or equal to 30 kg/m². Morbid obesity was defined as a BMI greater than or equal to 35 kg/m². The primary outcome was unplanned conversions to open. Other outcomes measures assessed included anastomotic leak, operative time, surgical site infections, length of hospital stay, readmissions and mortality. Statistical analyses were performed using SPSS 22.0 (IBM SPSS, USA). 1490 patients had robotic-assisted and 4967 patients had laparoscopic rectal resections between 2015 and 2016. Of those patients, 561 obese patients had robotic-assisted rectal resections and 1824 patients underwent laparoscopic rectal surgery. In the obese cohort, the rate of unplanned conversion to open in the robotic group was 14% compared to 24% in the laparoscopic group (P < 0.0001). Median operative time was significantly longer in the robotic group (248 min vs. 215 min, P < 0.0001). There was no difference in anastomotic leak or systemic sepsis between the laparoscopic and robotic rectal surgery groups. In morbidly obese patients (BMI ≥ 35 kg/m²), the rate of unplanned conversion to open in the robotic group was 19% compared to 26% in the laparoscopic group (P < 0.027). There was no difference in anastomotic leak, systemic sepsis or surgical site infection rates between robotic and laparoscopic rectal resection. Multivariate analysis showed that robotic-assisted surgery was associated with fewer unplanned conversions to open (OR 0.28, P < 0.0001). Robotic-assisted surgery is associated with a decreased risk of conversion to open in obese and morbidly obese patients when compared to conventional laparoscopic surgery. However, robotic surgery was associated with longer operative time and despite improvement in the rate of conversion to open, there was no difference in complications or length of stay. Our findings are limited by the retrospective non-randomised nature of the study, demographic differences between the two groups, and the likely difference in surgeon experience between the two groups. Large randomised controlled studies are needed to further explore the role of robotic rectal surgery in obese and morbidly obese patients.