Is rectal washout necessary in anterior resection for rectal cancer? A prospective clinical study

Implantation of exfoliated malignant cells has been suggested as a possible mechanism of tumor recurrence in colorectal anastomoses that might be prevented by cytocidal washout. The aim of our study was to assess whether malignant cells are likely to be collected by a circular stapler introduced transanally to perform an anastomosis and to observe local recurrences during follow-up, with special attention to the washout status of patients.

Between May 1999 and March 2004, 96 patients with carcinoma of the rectum and distal sigmoid colon undergoing anterior resection under the care of three surgeons (only one of whom routinely performed rectal washout) were prospectively studied. While 38 patients had rectal washout with 5% povidone-iodine before anastomosis, 58 patients did not. A circular stapler was used for anastomosis, and the stapler was immediately rinsed in 100 ml of saline. The fluid was then classified as "acellular," "malignant cells identified," or "benign cells identified" by pathologists.

Malignant cells were collected from the circular stapler after use in 3 patients (8%) on whom rectal washout was performed and in 2 (3%) patients who did not have rectal washout performed (P=0.631). Three patients (8%) in the washout group developed local recurrence, and 2 patients (3.4%) in the no-washout group had local recurrence (one was anastomotic recurrence) (P=0.338). The median follow-up time was 23 (range: 9-70) months.

There were no differences in terms of the number of patients who had malignant cells collected from the circular stapler and local recurrence rates between the two groups. Although this is not a randomized study and size and mean follow-up time of the study were not sufficient, our results did not offer rational arguments in support of intraoperative rectal washout when a circular stapler is used after low anterior resection for carcinoma. Because of the limitations of our study, however, we are unable to arrive at a definite conclusion regarding rectal washout. There is a need for a randomized, controlled, large-scale, multicenter trial to establish the clinical relevance of intraoperative rectal washout.