Prevention of anastomotic tumour take by on-table colon washout with povidone-iodine - An experimental study in rats

The presence of organic material in the intestinal lumen is reported to interfere with the efficacy of cancericidals when used in low concentrations to prevent anastomotic recurrence in colorectal cancer surgery. We aimed at investigating the efficacy of intra-operative whole-colon washout using povidone-iodine in an experimental model of anastomotic tumour growth. A large inoculum of highly 'tumorigenic' carcinoma cells was instilled in the colonic lumen of Fischer rats. The whole-colon water washout was intended to remove the luminal organic material. This was followed by irrigation of increasing concentrations of povidone-iodine up to 5% with or without additional incubation for 10-20 min. Five animals died after 30 min incubation with povidone-iodine 5%. Tumour take was observed in all control animals including after irrigation with physiological saline. Increasing the povidone-iodine concentration from 1 to 5% reduced the rate of tumour take, but not significantly. The anastomotic tumour growth was significantly reduced after tumour cell inoculation followed by whole-colon ravage and luminal incubation for 20 min with povidone-iodine 5%. Application of intra-operative whole-colon washout to remove the luminal 'organic material' followed by luminal application of povidone-iodine 5% for a sufficient incubation time could reduce the risk of anastomotic recurrence in colorectal cancer surgery.