A novel shape-locking guide for prevention of sigmoid looping during colonoscopy

Background: Looping of the endoscope in the sigmoid colon and other colonic segments often represents a significant challenge to the performance of comfortable, complete, and swift colonoscopy. This report describes the design and operation of a new device that addresses this problem, together with preliminary preclinical experience with this use of this shape-locking guide (SG-1). Methods: The shape-locking guide is an overtube that can be converted from a flexible to a rigid configuration on demand. When in the rigid configuration, the shape-locking guide is designed to protect the colon wall from lateral forces exerted by the colonoscope. The shape-locking guide was evaluated in vitro by using an artificial colon model to learn how to operate it, and to assess feasibility for prevention of colon looping. In addition, safety was assessed in vivo in a pig model. Results: In vitro, the shape-locking guide prevented colonic looping and, thereby, aided completion of "colonoscopy" in the artificial colon model. Subsequent in vivo studies demonstrated that use of the shape-locking guide is safe and feasible; it performed well with respect to ease of insertion and avoidance of sigmoid looping. There was no evidence of significant injury to the colon or adjacent abdominal viscera. Conclusions: This preliminary study shows that use of the shape-locking guide is safe and that it has performance characteristics that may assist the performance of colonoscopy. Human trials are being undertaken.