Miss rate of right-sided colon examination during colonoscopy defined by retroflexion: an observational study

Background: Colonoscopy is less effective in the proximal compared with the distal colon. Objective: To describe the success rate, yield, and safety of retroflexion of the right side of the colon after a careful forward-viewing examination. Design: Prospective observational study. Setting: Tertiary-care hospital outpatient endoscopy center and associated ambulatory surgery center. Patients: A total of 1000 consecutive adults undergoing elective screening or surveillance colonoscopy, without previous bowel resection, inflammatory bowel disease, or polyposis syndromes. Intervention: After cecal intubation, a careful examination of the cecum to the hepatic flexure was performed in the forward view with removal of all identified polyps. The colonoscope was then reinserted to the cecum and retroflexed, and examination was performed to the hepatic flexure in retroflexion. Main Outcome Measurements: Success rate, per-polyp and per-patient miss rates, and adverse events rate of retroflexion. Results: Retroflexion was successful in 94.4% of patients. Looping in the insertion tube was the apparent cause of 89% of failed attempts. The forward view identified 634 proximal colon polyps and 497 adenomas, and retroflexion identified an additional 68 polyps and 54 adenomas, representing a per-adenoma miss rate of 9.8% and an intention-to-treat, per-patient adenoma miss rate of 4.4%. Older age, male sex, and polyps seen on the forward view predicted polyps seen on retroflexion. There were no adverse events. Limitations: Single-center, uncontrolled study with only 2 endoscopists. Conclusions: Right-sided colon retroflexion is generally achievable and safe in our hands. The yield is comparable to that expected from a second examination in the forward view. (Gastrointest Endosc 2011;74:246-52.)