Total Underwater Colonoscopy versus Standard CO2 for Adenoma Detection: A Randomized Controlled Tandem Colonoscopy Trial

• Published in: The American journal of gastroenterology Vol. 113; p. S275
• Main Authors: Anderson, Joseph, Kahi, Charles J, Garcia, Jonathan R, Sullivan, Andrew W, Rex, Douglas K
• Format: Journal Article
• Language: English
• Published: New York Wolters Kluwer Health Medical Research, Lippincott Williams & Wilkins 01-10-2018
• Subjects: Colonoscopy; Gastroenterology; Polyps; Tumors
• ISSN: 0002-9270; 1572-0241

Introduction: Although water exchange may improve adenoma detection when compared to CO2, it is unclear whether water is a better medium for insufflating the lumen and inspecting the mucosa. Total underwater colonoscopy (TUC) involves the use of water exchange with the air valve shut off during insertion, followed by the performance of the exam, including inspection of the mucosa and polypectomy under water. Our goal was to compare TUC to standard CO2 using a randomized tandem colonoscopy design. NCT03231917 Methods: We randomized participants to have tandem colonoscopies using TUC or CO21st to insufflate the colon and inspect the mucosa for adenomas, followed by a 2nd exam with the other method.. The primary endpoints were polyp and adenoma miss rates for the first exam, calculated as the number of additional polyps detected during the 2nd exam divided by the total number of polyps detected by both exams. Inspection times were calculated by subtracting time for polypectomy, and care was taken to keep the times equal for both exams. Co-variates included participant age and sex, indication, personal history of neoplasia, family history of CRC, time (insertion, inspection, withdrawal and total), volume of water infused during insertion and withdrawal, Boston Bowel Prep Score, and sedation. All results are polyp level analyses. Results: Based on sample size calculations, 121 participants were randomized (61 having CO21st and 60 TUC 1st)(Endoscopist 1: 25 TUC 1st/26 CO2 1st; Endoscopist 2: 11 TUC 1st/ 9 CO2 1st; Endoscopist 3: 24 TUC 1st /26 CO2 1st). There were no significant differences between groups with respect to age, sex, family history, BBPS and sedation. The insertion time was longer for TUC than CO2. Characteristics for TUC versus CO2 exams are shown in Table 1. The overall polyp miss rate was significantly higher for the TUC 1st group (81/237;34%) versus the CO2 1st cohort (57/264; 22%)(p=0.002). The adenoma miss rate was also higher for the TUC first group (52/146; 36%) versus the CO2 group (37/159; 23%) (p=0.025) (Table 2). However, 1 of the 3 endoscopists had a numerically higher miss rate for CO2. After adjusting for times, participant characteristics and bowel preparation, TUC was more likely to miss polyps/ adenomas than CO2 (Table 3). Conclusion: Our findings suggest that TUC is not a superior medium to CO2 to insufflate the colon and inspect the mucosa for polyps or adenomas. However, TUC may benefit some endoscopists, an issue which requires further study.