An aid to the assessment of bowel preparation prior to colonic resection.

The removal of solid and liquid faeces from the colon is a prerequisite for safe colonic resection. Previous studies attempting to quantify evacuation of the colon have relied on a subjective opinion on isolated areas of the colon at the time of surgery. In an attempt to validate the surgeon's opinion, we have studied the efficiency of bowel preparation in 55 patients undergoing elective surgery requiring bowel preparation. Efficiency of bowel preparation has been assessed by (i) the subjective evaluation of the operating surgeon, (ii) the weight of faecal residue in the resected colon, and (iii) the production of a 'granule index' based upon the removal of Portex granules from the colon by preparation as measured on plain abdominal X-rays before and after preparation. The correlation between weighed faecal residue and the subjective assessment was poor. In 7 of 20 patients assessed subjectively as having no residue, faecal loading was in excess of more than 0.1 g/cm. The surgical assessment did not correlate with the clearance of Portex granules and two patients who had complete clearance of granules were judged poorly prepared. Surgeons are generally poor judges at assessing success or failure of bowel preparation. Standardisation of success of bowel preparation is important in the comparison of clinical trials and Portex granules would appear to give an accurate preoperative assessment of the efficiency of bowel preparation.