Two operators are usually required to perform the spiral enteroscopy technique given the fact that both the overtube and the instrument have to be manipulated during the procedure. The overtube is installed on the enteroscope using an interlocking device, which can switch between a longitudinal (advance-withdrawal) and rotational axis of freedom for the scope within the overtube. The procedure can be performed with moderate sedation, monitored anesthesia care (deep sedation) or with general anesthesia depending on patient, indication and operator variables. If general anesthesia is used for anterograde procedures, it is advisable to deflate the endotracheal balloon while the spiral is advanced through the upper esophagus to avoid trauma. Infrequently, in patients with significant cervical spine disease or cervical osteophytes, the overtube cannot be advanced past the upper esophagus and an alternative enteroscopy method has to be employed [2]. Once past the upper esophageal sphincter, the fixed overtube-enteroscope unit is carefully advanced through steady rotation through the stomach into the duodenum, keeping in mind the possibility of occult strictures. Non-obstructive esophageal Shatzki’s rings are usually inconsequential, but strictures less than 15 mm in diameter should be traversed with caution. Once the overtube engages the pylorus and duodenum, the scope-overtube unit usually advances fairly easily with steady clockwise rotation into the small bowel. When the entire effective part of the overtube has been inserted in the patient and rotational advancement stops or when the operator encounters unusual rotational resistance, the unit can be unlocked again and the scope advanced independently in the small bowel to the maximal point of insertion or until pathology is found.

For the retrograde approach, the overtube serves primarily to “splint” the endoscope (usually an enteroscope) during insertion into the colon and avoid looping (Fig. 9.3). The retrograde spiral overtube can rarely be engaged through the ileocecal valve. Instead, in a relatively straight configuration and under favorable valve orientation, the enteroscope itself can be advanced relatively easily in the ileum (Video 9.1). In a small study, the terminal ileum was intubated in 100 % of patients and the depth of insertion past the ileocecal valve was estimated at 100 cm (range 50–150 cm) [3]. Controlled visualization and, on a case-by-case basis, endoscopic therapy occurs during system withdrawal, which is essentially the reverse of the process described previously (i.e., counter-clockwise rotation of the overtube with the scope either in “locked” or “free” position to allow a more nimble handling of the scope as well as diagnostic and therapeutic interventions). In order to increase the traction of the overtube on the small bowel, only the minimum amount of gas (air or CO₂) is insufflated during advancement. A more detailed description of the procedure is available [1].