A systematic review of the impact of post-operative oral fluid intake on ileus following elective colorectal surgery

Introduction: Ileus (delayed return of bowel function after surgery) is one of the highest priority research questions in modern day colorectal practice. Current Enhanced Recovery After Surgery (ERAS) guidance either does not include a specific recommendation for volume of postoperative oral fluids/foodstuffs or suggests ad-lib fluids. It is unclear if the volume of intake affects ileus rates. This systematic review aimed to determine the optimal fluid volume for patients to consume day one after elective colorectal surgery. Methods: The literature was searched across seven databases, September 23, 2020. Randomised controlled trials of adults undergoing elective colorectal surgery, comparing oral intake postoperatively were eligible for inclusion. Two blinded reviewers assessed papers with disagreements resolved by a third independent reviewer. Main outcomes were 'resolution of postoperative ileus' and 'length of hospital stay'. Secondary outcomes included vomiting, mortality and complications. Results: Of 2175 screened papers, eight were eligible for inclusion. All studies gave a clear liquid diet postoperatively. The comparison groups followed a traditional nil-by-mouth approach. All studies showed a minor reduction in postoperative ileus and hospital stay in the intervention group, but we are unable to determine the optimal postoperative oral fluid volume. The low number and poor quality of studies was a significant limitation. None of the trials were conducted within an ERAS protocol: only 883 patients were included in total. Conclusions: From the current literature it is unclear how postoperative oral fluid volume intake affects gastrointestinal function and ileus in elective colorectal surgical patients. This remains an important area for further research.