Background: Colonoscopes are designed with balance between flexibility, required to negotiate angulations, and\r\nstiffness, required to counteract the propensity for looping in unfixed sections of the colon, which retards\r\nadvancement of the instrument. Colonoscopy can be challenging with old instruments that have lost native\r\nstiffness and become less responsive to torquing.\r\nA new intraluminal stiffening device has become available in two grades of stiffness. However, there is no\r\npublished evidence of its effectiveness. This randomized, controlled trial was designed to determine the\r\neffectiveness of the stiffening wires in improving cecal intubation rate and time following routine application. A\r\nsecondary analysis determines effectiveness of application only after intractable failure with the unaided\r\ncolonoscope.\r\nMethods: The colonoscope tested was an Olympus CF-100TL, approximately fifteen years old. Patients were\r\nrandomly assigned to the unaided colonoscope or the standard or firm wire introduced routinely on entry into\r\ntransverse colon. Each phase of colonoscopy was timed. Failure to advance the colonoscope for 5 minutes (despite\r\nusual manipulations to minimize looping) required switching to another intervention according to a prescribed\r\nmethodology and the originally assigned intervention was recorded as failed.\r\nResults: The study was terminated after accrual of 112 participants (target sample size 480) because the colonoscope\r\nrequired repairs (no damage attributable to stiffening wires) which would have been uneconomical. There were no\r\nstatistically significant differences between per-protocol cecal intubation rates (81.1, 71.1 and 70.3 percent respectively),\r\na finding which persisted after multiple imputation for a virtual sample size of 480. Similarly, there were no statistically\r\nsignificant differences between per-protocol cecal intubation times (15, 16.2 and 13.9 minutes). However, a statistically\r\nsignificant improvement in cecal intubation rate (from 81.1% to 97.3%, P = 0.0313) was achieved when the wires were\r\napplied after intractable failure of the unaided colonoscope in the first intervention group.\r\nConclusions: Routine application of either stiffening wire does not improve caecal intubation rate nor time compared\r\nto the unaided colonoscope. However, application of the stiffening wires after intractable failure of the unaided\r\ncolonoscope enabled a statistically significant improvement in cecal intubation rate.
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