The rationale for bowel preparation is to decrease the amount of stool within the colon and to thereby reduce the volume of bacteria, assuming this will improve the healing of a colonic anastomosis, decrease the risk of leak and surgical site infection, and help bowel manipulation intraoperatively. However, there is controversy regarding the type of bowel preparation that should be administered, as well as the addition of antibiotics to preoperative mechanical preparation.
There is only one multicenter, randomized, prospective study comparing two bowel preparations: polyethylene Glycol (PEG) vs sodium phosphate (SP), along with a comparison with ertapenem and cefotetan, favoring the SP. The rest of the trials focus on comparing bowel preparation vs no bowel preparation, with contradicting results on anastomotic leakage, surgical site infection (SSI) and intra-abdominal infection.
The key factor may be the oral antibiotics given with the preparation, as they have been proven to decrease the incidence of SSI, as well as many other parameters. Several surgical guidelines recommend the addition of oral antibiotics prior to colorectal surgery, including in Enhanced Recovery programs (ERAS).
In conclusion, sodium phosphate is superior to PEG but due to its high risk nephrotoxicity, it is seldom used. Further studies comparing the prophylactic antibiotics administered both intravenously and orally are required.