Colonoscope with a sub-distal hyper-flaccid segment for improved insertion at colonoscopy: a randomized study

In sharp bends, particularly in the colonic flexures, the axial pushing force conveyed to the distal actively bending tip of the endoscope may cause impaction rather than progression. It is hypothesized that colonoscopes with a very flaccid segment immediately proximal to the distal bending tip might reduce this problem.

Two prototype colonoscopes with a flaccid passively bending segment (either progressively graded or ungraded flaccidity) positioned immediately proximal to the distal actively bending tip was evaluated in a single-blinded randomized study. The primary end-point was patients' evaluation of pain.

Altogether, 400 patients were randomized 1:1 to examination with a prototype (60 patients to endoscope with graded flaccidity; 141 to the endoscope with ungraded flaccidity) or a standard colonoscope. The groups were similar regarding age, sex and previous abdominal surgery. Severe pain was reported by 7% of patients in the prototype and 18% in the standard group (p = 0.001). There was a trend toward shorter cecal intubation time in the prototype group (mean 14.1 min, 95% CI 12.8-15.3) compared to the standard group (mean 15.5 min, 95% CI 14.3-16.7) (p = 0.12) and similar intubation rates (89% and 85%, respectively). Results for first (ungraded flaccidity) and second (graded flaccidity) generation prototypes collectively were similar to the second generation separately.

The concept of an endoscope with a hyper-flaccid segment may facilitate negotiation of sharp bends and reduce pain without compromising cecal intubation rate or intubation time.