Post written by Mike Tzuhen Wei, MD, from the Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, Stanford, and Department of Gastroenterology and Hepatology, Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA.

Loop formation can impede scope advancement, destabilize the tip, and cause pain. While there are strategies to overcome loop formation, there continues to be a need for novel instruments. In August 2019, the Pathfinder endoscope overtube (Neptune Medical, Burlingame, California, USA) was approved by the United States Food and Drug Administration. The endoscope overtube is 85-cm long and is designed to accommodate a pediatric colonoscope. If necessary, after advancing the overtube to the desired location, the pediatric colonoscope can be exchanged for a smaller diameter upper endoscope or enteroscope. While extremely flexible in its native state, once the single-use overtube has been advanced to the desired location, application of a vacuum to the overtube can stiffen the tube 15 fold. The stiffened overtube allows the endoscope to advance without loop formation. From May 2019 to February 2020, 29 patients were consecutively treated at 2 hospitals utilizing the rigidizing overtube. These patients are presented in our case series.

In our 29-patient series, we wanted to demonstrate that the rigidizing overtube is useful in a variety of clinical scenarios including incomplete colonoscopy with standard instruments, endoscopic resection when the scope tip requires stabilization, prevention of painful looping, enteroscopy, and altered-anatomy ERCP.

Of the 29 patients consecutively treated utilizing the rigidizing overtube, 1 patient received upper endoscopy (3.4%), 24 received colonoscopy (82.8%), and 4 received enteroscopy (13.8%). Indication for overtube use included incomplete colonoscopy (N=12; 41.4%), enhancing insertion depth not feasible with standard endoscopy (N=6; 20.7%), and scope stabilization during endoscopic resection (N=11; 37.9%).

Of the 22 lower endoscopy cases without history of colonic resection and with time to cecum, median cecal intubation time was 5 minutes (IQR 4.25-7 minutes). In the 12 cases of incomplete colonoscopy, cecum was reached in all cases, with a median cecal time of 6 minutes (IQR 4-7.25 minutes). Out of the 29 cases, there were 2 cases in which the overtube did not facilitate the procedures. In 1 case, the overtube did not improve scope stability to allow for safe polyp removal by ESD. In another, the overtube was unable to help maintain a retroflexed position and allow for removal of a leiomyoma at the gastroesophageal junction. In both cases, the procedures were completed without the overtube. No adverse events were experienced in any of the study patients.

In our case series, we demonstrate that the rigidizing overtube is useful in a variety of clinical scenarios including incomplete colonoscopy with standard instruments, difficult endoscopic resection, prevention of painful looping, enteroscopy, and altered-anatomy ERCP. We feel the ability of the overtube to easily switch from flexible to rigid allows for further facilitation of procedures, especially in difficult colonoscopies. The ability to exchange the pediatric colonoscope for a longer enteroscope is particularly appealing in cases where further attempts to advance a colonoscope appear futile.

Figure 1. Pathfinder endoscope overtube (pictured in white), fits over the scope. There is a stopcock attached to the overtube with 2 positions: in the first position the stopcock connects the vacuumable volume to atmosphere, maintaining the overtube in the flexible position; in the second position, the stopcock connects the vacuumable volume to a source of vacuum which allows the overtube to become rigid, leading for easier navigation of the scope through the colon.

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