Influence of rectal washout on bacterial counts in the rectal stump

Forty-three patients undergoing a restorative colorectal resection were randomized to have their rectal stump washed out with either 0.9 per cent saline, 2.5 per cent povidone-iodine or 0.3 per cent sodium hypochlorite. The bacterial counts before and after washout for Escherichia coli and Bacteroides fragilis were compared using the Mann-Whitney U test. There was no significant difference in the counts for E. coli before and after washout with saline (log 9.7-log 9.7 organisms/ml) and saline had no influence on the counts of B. fragilis (log 7.9-log 6.5 organisms/ml). Hypochlorite was associated with a significant reduction in E. coli counts (log 6.1-log 1.1 organisms/ml, P less than 0.005) and the counts of B. fragilis (log 8.1-log 0.0 organisms/ml, P less than 0.005). The counts of B. fragilis were significantly reduced by povidone-iodine (log 8.1-log 1.1 organisms/ml, P less than 0.005) but there was no significant reduction in counts of E. coli (log 5.6-log 5.3 organisms/ml). The data suggest that sodium hypochlorite is better than povidone-iodine or saline as a rectal washout for colorectal anastomosis.