Mechanical bowel preparation (MBP) is a method of cleansing the bowel prior to surgery which has been used routinely for many years with the aim of reducing post-operative complications.

However, several recent studies have shown no statistically significant evidence of short-term benefit from this procedure, and Guenaga and co-workers suggested in the most recent update of a Cochrane review of this procedure that there is a trend towards poorer short-term outcomes and particularly to anastomotic leakage. However, there have as yet been no reported long-term outcomes of MBP for colorectal surgery.

Gary Nicholson from the West of Scotland Cancer Surveillance Unit, University of Glasgow, UK and his colleagues have now conducted a retrospective cohort study of MBP before surgery for colon cancer over a follow-up period of five years.

This study included all patients undergoing potentially curable surgery for cancer of the colon in the West of Scotland in the years 2000-2005. Exclusions included emergency admission and the incidence of rectal lesions or multiple tumours. Patients were categorised demographically and by tumour stage and socioeconomic characteristics, and records of surgical complications were obtained from standard clinical audits. The primary outcome was overall survival five years after surgery.

A total of 1730 patients underwent surgery for colon cancer in the participating area of Scotland during the study period and were therefore included in the study. 1460 (84.4%) of these patients received MBP before surgery; the mean age of all participants was 69.1 and slightly more than half (51%) were male.

Patients whose surgery was undertaken as an emergency were less likely to receive MBP than those who underwent elective surgery.

The median follow-up period was 3.5 years (range: 0-1-6.7 years) and all-cause survival was significantly higher in those patients who had received MBP throughout that time period. In multivariate analysis, the survival advantage remained after adjustment for age, sex, Dukes' stage and socioeconomic circumstances, but it was no longer significant after adjusting for whether the surgery was elective or emergency.

The fully adjusted hazard ratio for all-cause mortality was 0.85 (confidence interval 0.67-1.10). This suggests that factors associated with emergency surgery other than lack of MBP are responsible for an increase in risk of post-operative death that extends more than three years after the operation.

There was also no statistically significant difference between patients receiving or not receiving MBP in complications reported in the 30 days following surgery.

Manual bowel preparation remains standard practice in many countries, even though it is unpleasant for patients to undergo and time-consuming for nurses to oversee, particularly in patients who are elderly or otherwise frail. Previous studies have shown that it confers no statistically significant benefits in the immediate post-operative period.

Nicholson and his colleagues have now shown that no apparent long-term benefit is conferred by this procedure. However, this retrospective study of patients in one area, in which the choice of pre-operative procedure was made on a case-by-case basis by the individual surgeon concerned, is open to bias.

Nicholson and his colleagues suggest that a multi-centre, randomised controlled trial would be needed to prove that there is no overall benefit from this procedure.

References

Guenaga, K.K.F.G., Matos, D. and Wille-Jørgensen, P. (2009). Mechanical bowel preparation for elective colorectal surgery. Cochrane Database of Systematic Reviews 2009, Issue 1. Art. No.: CD001544.

DOI: 10.1002/14651858.CD001544.pub3

Nicholson, G.A., Finlay, I.G., Diament R.H., Molloy, R.G., Horgan, P.G. and Morrison, D. S. (2011). Mechanical bowel preparation does not influence outcomes following colonic cancer resection. British Journal of Surgery 98, 866–871

DOI: 10.1002/bjs.7454