Effect of Second Sigmoid Colon Intubation During Colonoscopy on Adenoma Detection Rate in Overweight and Obese Patients: A Prospective Randomized Controlled Trial

INTRODUCTION: The sigmoid colon is the most tortuous part of the large intestine and is often the most easily compressed during intubation and more easily missed during withdrawal observation. This study aimed to ascertain whether a second sigmoid colon intubation could enhance the adenoma detection rate (ADR). METHODS: We conducted a randomized controlled trial of patients 45 years and older with a body mass index over 24 who underwent colonoscopy. At the time of the first withdrawal to the rectum, patients were randomized to the standard withdrawal (SW) group, which underwent withdrawal to the anus, or the second intubation (SI) group, which underwent reinsertion into the sigmoid colon. During the SI, we pushed the colonoscope forward without straightening it, allowing for slight looping that could be used to flatten the colonic folds as the tip of the instrument was advanced. Observations were made during both the intubation and withdrawal. The ADR in the sigmoid colon was the main result. RESULTS: This trial involved a total of 650 patients, including 325 in the SI group and 325 in the SW group. In the sigmoid colon, the ADR and polyp detection rate in the SI group were substantially greater than those in the SW group (ADR 24.3% vs 14.5%, P = 0.001; polyp detection rate 29.2% vs 17.8%, P = 0.001). Older age, smoking, longer duration of the second inspection, and the identification of lesions during the initial withdrawal from the sigmoid colon were independent predictors of further adenomas discovered during the SI. DISCUSSION: Using a SI of the sigmoid colon can effectively enhance the detection rate of sigmoid colon adenomas and polyps.