A Randomized Clinical Trial of a Novel Stiffening Wire to Increase Depth of Insertion During Double and Single Balloon Enteroscopy

BACKGROUND Small bowel endoscopy has undergone a paradigm shift in the past decade. Prior to this, the small bowel was considered a 'black hole' due to our inability to visualize it endoscopically and the limited sensitivity of radiologic studies. This all changed with the development of capsule endoscopy, which gave physicians the ability to visualize the full length of the small bowel. Although widely considered a great leap forward, video capsule endoscopy is limited by its inability to perform any form of endoscopic intervention. Thus, something was needed to biopsy and treat the abnormalities detected with capsule endoscopy. Double balloon enteroscopy (DBE) was invented in Japan in 2001. Using an overtube and two inflatable balloons, DBE enabled deep intubation of the small bowel through a series of push and pull maneuvers to accordion the small bowel over the overtube. This procedure proved highly successful in the diagnosis and treatment of small bowel diseases. Subsequently, single balloon enteroscopy (SBE) was developed consisting of a single overtube balloon. Collectively, these techniques are called balloon assisted enteroscopy.

Balloon assisted enteroscopy can be performed using an antegrade (through the mouth) or retrograde (through the anus) approach. The two approaches are considered complimentary since the antegrade approach enables visualization of the proximal and mid small bowel while the distal portion is seen with the retrograde approach. Complete enteroscopy, or visualization of the entire small intestine, occurs when an antegrade enteroscopy is performed and the tattoo left at the depth of maximal insertion is reached during a subsequent retrograde procedure. Although considered to be the gold standard for enteroscopy, this is rarely achieved outside of expert centres in Japan. The reason for this is because of loop formation in the small intestine, commonly referred to as looping (Figure 1). Looping typically worsens as the depth of insertion increases and eventually prevents forward migration of the enteroscope.

Looping is not unique to enteroscopy and is a common problem encountered during colonoscopy. During colonoscopy, loops can be removed, by pulling back and torqueing the colonoscope. However, the loop often reforms when the colonoscope is pushed forward again. To counter this problem, colonoscopes have been developed with adjustable stiffness that can be changed during the procedure (Olympus Inc., Tokyo, Japan). Using this feature, the loop can be removed and the colonoscope stiffened prior to pushing forward to prevent loop reformation.

Although variable stiffness is available in colonoscopes, the same technology cannot be incorporated into enteroscopes due to its much thinner diameter. Recently, an enteroscopy stiffening wire has been developed by Zutron Medical LLC (Kansas, USA). This through the scope wire can be inserted as needed to increase the stiffness of the enteroscope. In theory, this should improve the performance of DBE/SBE and translate into deeper insertion although this has never been investigated. The objective of this randomized clinical trial is to answer this question.

STUDY DESIGN