Water during small-bowel capsule endoscopy: some cautions before going with the flow

We read with great interest the randomized controlled trial published by Zeng et al.1Zeng X. Ye L. Liu J. et al.Value of the diving method for capsule endoscopy in the examination of small-intestinal disease: a prospective randomized controlled trial.Gastrointest Endosc. 2021; 94: 795-802Abstract Full Text Full Text PDF Scopus (4) Google Scholar Remarking on a resemblance to water-immersion colonoscopy, the authors explored the impact of water ingestion—500 mL per hour after the small bowel is reached, coined as the “diving method”—in improving visualization, diagnostic yield, and completion rate of small-bowel capsule endoscopy (SBCE). The “diving method” was associated with a higher completion rate (92% vs 76%, P < .05) and improved visualization of the proximal-to-mid small bowel (P < .05). Nonetheless, no significant differences were observed on the number of lesions in each small-bowel third or on the detection rate. The authors advocate that the “diving method” increased the diagnostic yield. However, we believe that further studies are needed to prove that assumption. Besides the fact that “lesions” and “positive findings” lack explicit disambiguation, the only segment in which positive findings were significantly increased was the distal part of the small bowel, where visualization was not improved. Only the indications for SBCE were compared, not final diagnoses, potentially biasing the number of lesions and positive findings. In fact, a slight imbalance between groups, in the number of patients with Crohn’s disease or polyposis, could justify more positive findings in a certain group or bowel segment, unrelated to improved image quality. The higher completion rate in the “diving group” could be simply explained by a shorter, although nonsignificant, small-bowel transit time, which could ultimately compromise the diagnostic yield.2Egea Valenzuela J. Sánchez Martínez A. García Marín A.V. et al.Influence of demographic and clinical features of the patient on transit times and impact the on the diagnostic yield of capsule endoscopy.Rev Esp Enfermedades Dig. 2019; 111: 530-536Google Scholar This trial is an important step forward, bringing to debate several aspects that remain unsettled in SBCE: (1) the lack of consensus about the best preprocedural preparation,3Hookey L. Louw J. Wiepjes M. et al.Lack of benefit of active preparation compared with a clear fluid-only diet in small-bowel visualization for video capsule endoscopy: results of a randomized, blinded, controlled trial.Gastrointest Endosc. 2017; 85: 187-193Abstract Full Text Full Text PDF PubMed Scopus (30) Google Scholar,4Triantafyllou K. Gkolfakis P. Dimitriadis G.D. Abandon purgative bowel preparation before small-bowel capsule endoscopy? Not yet.Gastrointest Endosc. 2017; 85: 684Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar (2) the promising role of intraprocedural preparation,5Chetcuti Zammit S. Sidhu R. Capsule endoscopy: recent developments and future directions.Expert Rev Gastroenterol Hepatol. 2021; 15: 127-137Crossref PubMed Scopus (17) Google Scholar with water and lower quantities of isosmotic or hyperosmotic purgatives (important not only to evaluate safety and efficacy but also to perform dose-range finding studies); and (3) the lack of validated, reproducible, and easy cleansing scoring scales,6Ponte A. Pinho R. Rodrigues A. et al.Review of small-bowel cleansing scales in capsule endoscopy: a panoply of choices.World J Gastrointest Endosc. 2016; 8: 600-609Crossref PubMed Google Scholar as recently highlighted,7Dray X. Houist G. Le Mouel J.-P. et al.Prospective evaluation of third-generation small bowel capsule endoscopy videos by independent readers demonstrates poor reproducibility of cleanliness classifications.Clin Res Hepatol Gastroenterol. 2021; 45: 101612Crossref Scopus (7) Google Scholar which are critical to evaluate small-bowel preparation protocols. All authors disclosed no financial relationships.