BACKGROUND: Colonoscopes with short bending sections facilitate retroflexion but their effect on other aspects of colonoscope insertion are unknown. We sought to determine the impact of short bending on cecal insertion, terminal ileal intubation, and proximal colon retroflexion. METHODS: Two studies were performed. In study 1, we randomized 104 adult patients with intact colons to undergo colonoscopy with a standard pediatric colonoscope (Olympus PCF-160), a prototype pediatric colonoscope with short bending in four directions (PCF-AYL), or a prototype pediatric colonoscope with short bending in two directions, and normal bending in two directions (PCF-AY3L). In study 2, we randomized 70 patients with intact colons to undergo colonoscopy with a prototype 170 degrees wide angle colonoscope (CFQ160-WL) with a standard bending section length or to a prototype 170 degrees colonoscope with a short bending section (CFQ160-W2L). RESULTS: In study 1, the cecum was reached in all patients. Using the AYL, the cecal intubation time (4.08 min) was significantly longer when compared to both the PCF-160 (2.62 min; p= 0.0001) and the AY3L (3.25 min; p= 0.02). The AYL required the application of abdominal pressure (79%) and activation of the variable stiffness device (70%) more frequently when compared to both the PCF-160 (32%; p= 0.0001 and 41%; p= 0.02, respectively) and the AY3L (34%; p= 0.0003 and 41%; p= 0.02, respectively). Successful cecal retroflexion was possible less often with the PCF-160 (57%) when compared to either the AYL (94%; p= 0.005) or AY3L (91%; p= 0.001). The ability to intubate the terminal ileum was similar in all three groups (PCF-160 and AY3L 100%; AYL 94%) as was the time needed to intubate (p= 0.73). Depth of ti intubation was deeper for the PCF-160 when compared to the AYL (p= 0.0002) or AY3L (p= 0.02). There was a trend toward deeper ileal intubation with the AY3L compared to AYL (p= 0.09). In study 2, no difference was noted in cecal intubation time (p= 0.1) or in frequency of application of abdominal pressure (p= 0.28), position change (p= 0.15), or activation of the stiffening device (p= 0.46). Cecal retroflexion was successful more often when using the W2L when compared to the WL (p= 0.00001). CONCLUSION: Short bending sections facilitate proximal colon retroflexion for both pediatric and adult colonoscopes, but can negatively impact cecal insertion and terminal ileal intubation in pediatric colonoscopes. A pediatric colonoscope with short bending in only two directions had good function for both cecal insertion and proximal colon retroflexion.
