Outcome parameters
To date, there is no consensus in the measurement of POI. Thus, the measurement of POI is currently the subject of research8. We selected the most frequently used criteria found in the work of Chapman et al.9: time to passage of first flatus, time to passage of first stool, time to solid food tolerance, number of patients requiring post-operative introduction of nasogastric tube, time to first bowel movement at the auscultation and post-operative length of hospital stay. The following parameters were reported in hours: first gas, first stool, solid food resumption and bowel movement. The duration of hospitalisation was stated in post-operative days and the reintroduction of nasogastric tube was reported in number of patients. Studies were eligible if one or more of these outcomes were reported or provided by the Corresponding Author. The mean age of each individual study population was recorded in addition to the percentage of male participants and the mean operative time. No surgical complications beyond ileus were recorded due to heterogeneity in reporting complications.