Water-assisted colonoscopy in inflammatory bowel diseases: From technical implications to diagnostic and therapeutic potentials

Figure 1 The main differences between water-immersion and water-exchange colonoscopy techniques are as follows: Both techniques, derivatives of water-assisted colonoscopy, utilize water to facilitate the completion of the examination, with distinct differences between them. Compared to standard techniques, water-immersion (WIC) and water-exchange (WEC) offer numerous advantages regarding inflammatory bowel disease (IBD). They facilitate reaching the caecal base with a higher likelihood of achieving terminal ileum intubation. They assist in colorectal cancer screening colonoscopy, which these patients are more susceptible to, by increasing adenoma detection rates both during instrument withdrawal (WIC) and throughout the procedure, including insertion (WEC). Moreover, procedural comfort for patients with IBD, who already suffer from gastrointestinal disorders, is improved to varying degrees with both techniques. In the figure, what pertains (for each parameter indicated in the grey-background boxes) to the WIC is in the blue boxes, while what pertains to the WEC is in the red boxes. WEC: water-exchange colonoscopy; ADR: adenoma detection rate.

Figure 2 Pain-related data emerged from the two primary studies (A and B) conducted in an inflammatory bowel disease setting, comparing water-assisted colonoscopy techniques with standard gas-based colonoscopy. In both cases, pain was graded using a Likert scale from 0 to 10. A: A discomfort score in the paper by Falt et al[39]; B: A pain score by Shi et al[38]. Unlike the latter, the former study recorded these scores separately for the insertion and withdrawal phases of the procedure. The results from the first study (A) indicate that the water-exchange technique (WEC) was drastically and significantly superior to the gas-based colonoscopy (GBC) technique during both the insertion and withdrawal phases. In the second study (B), a broader comparison was conducted, including GBC, WEC, and the water-immersion technique (WIC). Although WIC and WEC did not show significant differences in pain scores, both were superior to the GBC technique. Continuous numerical values are expressed in both graphs (i.e., A and B) as means and SD of the respective means. The sample size (n) reported in each study is also indicated for each group. ^aP < 0.05, statistical significance.

Figure 3 Colonic fold distension during water-aided and gas-aided colonoscopy. A: An example of how the water-assisted colonoscopy technique avoids excessively distending the folds of the colon; B: In contrast to the gas-assisted technique.

Figure 4 Advantages of water-aided colonoscopy in colonic mucosal lesion resections. A: In the water-aided technique (upper portion of the figure), the introduction of water into the colon lumen allows for de-tensioning of the colonic walls and elevation of the mucosa (in pink) and submucosa (in yellow); B: This facilitates the removal of the mucosal lesion, as in an endoscopic mucosal resection using a snare; C: Conversely, in the gas-aided technique (lower portion of the figure), this elevating effect is absent, and the tension of the colonic walls is increased, resulting in reduced thickness of the mucosa and submucosa; D and E: Consequently, the submucosa must be elevated by injecting substances (e.g., diluted adrenaline in saline solution (D), to enable mucosal resection (E).

Figure 5 Benefits that water-assisted colonoscopy techniques can provide in patients with inflammatory bowel disease. Within this patient group, where colonoscopy serves multiple diagnostic, therapeutic, and preventive purposes (screening and surveillance for colorectal cancer), water-assisted techniques' advantages can prove particularly beneficial, especially considering the frequent need for these patients to undergo multiple colonoscopies throughout their chronic disease.