Comparison of cap-assisted endoscopy vs. side-viewing endoscopy for examination of the major duodenal papilla: a randomized, controlled, noninferiority crossover study

Background Use of a side-viewing endoscope is currently mandatory to examine the major duodenal papilla; however, previous studies have used cap-assisted endoscopy for complete examination of the papilla. The aim of this study was to compare cap-assisted endoscopy with side-viewing endoscopy for examination of the major duodenal papilla. Methods This was a prospective, randomized, blinded, controlled, noninferiority crossover study. Patients were randomized to undergo either side-viewing endoscopy followed by cap-assisted endoscopy or cap-assisted endoscopy followed by side-viewing endoscope. Photographs of the major duodenal papilla were digitally edited to mask the cap area before they were evaluated by three blinded external examiners. Our primary end point was complete visualization of the major duodenal papilla. Secondary end points were the ability to examine the mucosal pattern, the overview of the periampullary region, overall satisfaction, and time to locate the papilla. Results 62 patients completed the study. Complete visualization of the major duodenal papilla was achieved in 60 examinations by side-viewing endoscopy and in 59 by cap-assisted endoscopy (97% vs. 95%). The difference between the two examinations was 1.6% with a two-sided 95% confidence interval of -4.0% to 7.3%, which did not exceed the noninferiority margin of 8%. Cap-assisted endoscopy achieved better scores regarding the examination of mucosal pattern and overall satisfaction, whereas side-viewing endoscopy had a better overview score ( P <0.001, P =0.004, and P <0.001, respectively). There was no relevant difference in the median times to locate the major duodenal papilla. Conclusion Cap-assisted endoscopy and side-viewing endoscopy had similar success rates for complete visualization of the major duodenal papilla. Cap-assisted endoscopy is superior to side-viewing endoscopy regarding the mucosal pattern and overall satisfaction. Side-viewing endoscopy gives a better overview of the periampullary region.