A Transanal Technique for Accurately Measuring Distal Resection Margin in Rectal Cancer

Abstract

Purpose. Adequate distal resection margin (DRM) is an important factor determining the outcome of rectal cancer surgery. Traditionally, DRM is measured intra-abdominally after mesorectal excision. We proposed a new method to achieve sufficient DRM and avoid tumor cell exfoliation-caused bysurgical over-manipulation of the rectum involved with tumor. Material and Methods. Between October 2013 and February 2014, 17 patients (seven males, 10 females; median age: 71.1 yrs (range: 44-85 yrs) with rectal cancer who underwent low anterior resection (15 patients) or colo-anal anastomosis (two patients) received our intra-operative trans-anal technique. We used a plastic anoscopeto expand the anal canal and allow the use of a plastic ruler to measure the distal tumor margin. We then performed purse string suture ligation of the distal margin with 3-O vicryl leaving a sufficient length to use as a guide during surgery. During the colectomy, we performed the resection below the suture site. Results. The average ＂in vivo＂ DRM was 43.8 mm +/- SD of 12.7 mm (range: 20-80 mm). Average ＂ex-vivo＂ DRM was 32.7 mm +/- SD of 8.85 mm (range: 20-60 mm). The shrinkage rate, comparing ＂in vivo＂ with ＂ex vivo＂, was 25.3%. The average DRM, as measured by the pathologist (i.e., ＂in vitro＂), was 24.9 mm (range: 15-53 mm). The average shrinkage rate at pathology was 41.9%. Conclusions. Our transanal suture ligation method offers an optimal method to avoid insufficient DRM and tumor cell exfoliation caused by surgical over-manipulation of the rectum involved with tumor.