Water immersion sigmoidoscopy versus standard insufflation for colorectal cancer screening: A cohort study

Although the efficacy of water-assisted colonoscopy is well established, the role of water immersion sigmoidoscopy (WIS) remains unclear. We compared WIS with carbon dioxide insufflation sigmoidoscopy (CO₂S) on patient outcomes.

We conducted an analysis of prospectively collected data from a single-center quality improvement program about patients undergoing unsedated screening sigmoidoscopy (WIS and CO₂S) between May 2019 and January 2020. Outcomes studied included the following: Rates of severe pain <17% (score of ≥7 on a numeric rating scale of 0-10, and on a Likert scale), willingness to repeat the procedure without sedation, adequate bowel cleanliness >75% (proportion of Boston Bowel Preparation Scale score: 2-3) and adenoma detection rate (ADR).

In total, 234 patients (111 WIS; 123 CO₂S) were included. All patients were aged 58 years and 58.9% were female; baseline characteristics were comparable between groups. There were no significant differences in rates of severe pain (WIS: 16.5%, CO₂S: 13.8%; P = 0.586), willingness to repeat the unsedated procedure (WIS: 82.3%, CO₂S: 84.5%; P = 0.713), adequate bowel cleanliness (WIS: 78.4%, CO₂S: 78%, P = 0.999) or ADR (WIS: 25.2%, CO₂S: 16.3%; P = 0.106) between groups. However, average procedure times were longer with WIS (9.06 min) compared to CO₂S (6.45 min; P < 0.001). Overall, 29.6% of women reported that they would repeat sigmoidoscopy only if sedated.

WIS does not ameliorate tolerance to and quality of sigmoidoscopy screening measured by several scores. When offered a choice, the women's willingness to repeat WIS or CO₂S without sedation was poor and raises concern on the opportunity of screening sigmoidoscopy without sedation in these subjects.