Background & aims: Although several studies have been conducted on the relation between withdrawal time (WT) and adenoma detection rate (ADR) in the intact colonKim, little is known about the optimal WT needed to increase ADR in the postoperative colon. We investigated the association between WT and ADR in surveillance colonoscopy after colorectal cancer (CRC) surgery.
Methods: We conducted a retrospective cohort study of CRC patients who underwent 1st surveillance colonoscopy after curative colectomy. We excluded patients with incomplete inspection of colon during preoperative colonoscopy, inadequate bowel preparation, and total colectomy or subtotal colectomy. The colonoscopies were performed by 8 board-certified colonoscopists. The receiver operating characteristic curve of the WT revealed an optimal cutoff value of 7.8 min for adenoma detection. We divided the colonoscopists into fast and slow colonoscopists using the 8-min WT as cutoff, and compared the ADR between the two groups.
Results: We analyzed a total of 1341 patients underwent first surveillance colonoscopy after CRC surgery. Mean WTs by 8 colonoscopists during colonoscopy with and without polypectomy were 18.9 ± 13.7 and 8.1 ± 5.6 min, respectively. ADR varied from 29.3 to 50.6% by individual colonoscopists. Slow colonoscopists showed significantly higher ADR than fast colonoscopists (49.1% vs 32.2%, P < 0.001). The mean WT during colonoscopy without polypectomy for each colonoscopist and the detection rate of all neoplasia were positively correlated (Rs = 0.874, P = 0.005).
Conclusion: Because patients who underwent colorectal surgery possess high risk of metachronous CRC and adenoma, sufficient WT (8-10 min) is mandatory, despite short length colon due to surgery.
Keywords: Postoperative colon; Surveillance colonoscopy; Withdrawal time.