Prolonged cecal insertion time is associated with high amount of mucus in left colon during colonoscopy with water exchange

Aims Colonoscopy is the standard procedure to assess the mucosa of the colon. Colon must be prepared free feces or any residues capable of obstructing the mucosa of the colon for an adequate safety and security during the study. A poor bowel preparation diminishes the detection rate of preneoplastic lesions, increases the cost, time and the risk of complications associated to the procedure itself. Water exchange technique is well known to increase mucus production in left colon interfering with the complete mucosal visualization.The aim is to find an association between clinical variables and mucus amount in a colonoscopy with water exchange technique measured with Left Colon Mucus Scale (LCMS).

Methods Single-center prospective study was conducted in patients>18 years of age with indication for colonoscopy between January and July 2024. Bowel preparation was carried out using PEG complete or split dose. Colonoscopy was performed using water exchange technique with sterile water or 0.45% sodium chloride solution. Adequate bowel preparation was considered with a Boston Bowel Preparation Scale≥6, and a LMCS≤1. Demographic variables, endoscopic findings, factors associated with colonoscopy as the adenoma detection rate (ADR), the presence of sessile serrated adenomas and colonoscopy time were evaluated. Univariate and multivariate analyzes were performed, as well as logistic regression analysis for independent analysis.

Results A total of 92 patients were included, 63 female (68%),age 58±13, split dose PEG (77%).A good bowel preparation was in 51%. An LCMS≤1was achieved in 16 patients (17.4%); the ADR was of 53.3% and sessile serrated lesions were detected in 22 patients (23.9%); in the logistic regression analysis the only variable associated to an increased mucus production of left colon was the cecal insertion time>9 min (OR 1.24; 95% CI 1.11-1.39, p=0.043); any other variable don’t showed a statistically significant association, including the use sodium chloride solution.

Conclusions In colonoscopies with water exchange technique the presence of mucus in left colon becomes a usual condition, it seems that a protracted cecal insertion is the most important variable associated to this finding, this could imply the inflammatory effect of excessive manipulation of the sigmoid, it draws attention that the use of saline apparently didn’t exert a protective effect as previously reported, we need further studies to reinforce this conclusion.

Publication History

Article published online:
27 March 2025