Effect of rectal stump washout on the presence of free malignant cells in the rectum during anterior resection for rectal cancer.

Purpose: It is possible that implantation of viable malignant cells is one of the mechanisms of anastomotic recurrence in rectosigmoid cancer. The viability of shed intraluminal cells was previously established and malignant cells were retrieved on circular staplers in unwashed rectal stumps. The aim of this study is to evaluate the effectiveness of a defined and uniform washout protocol in eradication of intraluminal malignant cells during anterior resection.

Methods: In 14 consecutive patients the closed rectal stump was washed before insertion of the circular stapler. The washout was performed uniformly by instillation of ten increments of 50 ml of saline through a rectal tube. Samples from the first, fifth, and tenth washings were collected for cytologic examination. The presence or absence of malignant cells was then correlated with rectal stump length, length of the tumor-free distal margin, and differentiation and Dukes staging of the tumor.

Results: In 11 patients the first washing was positive for free malignant cells, and the fifth washing was still positive in 7 patients; however, the last (tenth) samples were clear in 10 patients, and malignant cells were recovered in only 4 patients. The rectal stump and the tumor-free distal margin were shorter in patients who still had positive cytology for free intraluminal malignant cells after stump irrigation with 500 ml of saline. No correlation was found with tumor differentiation or staging.

Conclusions: Free malignant cells are shed into the rectal stump during anterior resection. Mechanical lavage with saline effectively eradicates these cells; however, the completeness of cleansing is volume related. Incomplete cleansing with 500 ml of saline correlates with lower tumors. Technically more difficult surgery involves traumatic handling of the tumor and possibly induces shedding of more malignant cells. We suggest that rectal stump washout during anterior resection for carcinoma should be routine, and the volume of the lavage fluid should be larger than 500 ml.