A pilot study of a novel variable-stiffness stylet for efficient colonoscope insertion with ex-vivo colon model

Objectives: The variable-stiffness colonoscope is reportedly useful for making colonoscope insertion easier. However, this function is not associated with all colonoscopes. We developed a variable-stiffness stylet that can be inserted into the endoscope instrumentation channel to change the rigidity of the endoscope. Methods: We developed a stylet with adjustable stiffness and investigated its utility in colonoscope insertion using an ex-vivo model. Four endoscopists performed 24 colonoscope insertions, alternating between using the stylet (Stylet method) and the conventional method. We assessed insertion rate, rate of applying abdominal compression, and insertion time between the two groups. Results: In all procedures, the endoscope was inserted up to the cecum. There were significantly fewer external abdominal compressions with the Stylet method (1/12, 8.3%) compared to the conventional method (6/12, 50%). The insertion time was shorter with the Stylet method (140.9 ± 53.7 s) compared to the conventional method (181.3 ± 64.9 s). Conclusions: Using the variable-stiffness stylet, currently under development, resulted in significantly fewer external abdominal compressions and tended to have shorter insertion time.