Colonoscopy is essential for the diagnosis and treatment of colorectal disease. In particular, the indication range of colonoscopic treatment has been broadened owing to improved techniques for the endoscopic resection of colorectal tumors, endoscopic hemostasis, and endoscopic balloon dilatation of intestinal stenosis. As for colonoscopic devices, image quality as well as insertability has improved considerably. However, total colonoscopy is still technically difficult to perform in about 10% to 15% of subjects[7
]. Even though our hospital specializes in gastrointestinal endoscopy, we still encounter patients in whom total colonoscopy is technically difficult to perform. Excluding follow-up examinations after colorectal surgery or other procedures, we performed 3140 sessions of colonoscopy during the year of 2011. A conventional colonoscope could not be inserted to the cecum in 32 sessions (1.0%). In many patients with difficulty in scope insertion, barium enema examination was performed to evaluate sites of the colon that could not be assessed on endoscopy. Factors related to technical difficulty in colonoscope insertion have been reported to include advanced age, female sex, a low body mass index, an elongated colon or adhesions, multiple diverticula, and inadequate bowel preparation[7
]. In our series, the main factors that precluded colonoscope passage during SBE were an elongated colon and severe adhesions.
Patients in whom colonoscope insertion is expected to be technically difficult, especially those who are sensitive to discomfort and pain associated with colonoscopy, should receive adequate doses of analgesics and sedatives before examination. Manual compression of the abdomen by an assistant and the use of an overtube may facilitate scope passage in patients in whom insertion is difficult because of an elongated colon[11
]. In such patients, a variable stiffness colonoscope or a colonoscope with a long effective length should be used. Lichtenstein et al[12
] reported that the use of a small-caliber, push-type enteroscope with an effective length of greater than 2000 mm allowed total colonoscopy to be performed in about half of all patients in whom scope passage was difficult. If colonoscopy is performed in patients with severe adhesions in the colon after open surgery, a small-caliber colonoscope should be used. At present, very small-caliber colonoscopes with an outer diameter of 10 mm or less are commercially available. We previously reported that the use of a colonoscope with an outer diameter of 9.2 mm and an effective length of 1600 mm (CF-PQ260L®
, Olympus Co., Tokyo, Japan) allowed total colonoscopy to be performed in the majority of patients in whom scope insertion was precluded by an elongated colon and adhesions[13
]. Preliminary studies have suggested that the use of a guide-wire-directed endoscope or a spiral overtube can facilitate colonoscope insertion when difficulty is encountered[14
During colonoscope insertion, the scope may bend or form large loops in patients with an elongated colon. The presence of bowel adhesions can restrict mobility of the colon and cause sharp bends, which preclude scope passage. Excessive force to promote passage can injure the intestine. We performed colonoscopic examination by SBE in patients with a history of difficulty in scope insertion even by experienced endoscopists. A balloon attached to a sliding tube was inflated to grip and shorten the intestine, thereby preventing overextension of the intestine during the procedure and facilitating passage of the endoscope through regions with adhesion. Because the outer diameter of the SBE was only 9.2 mm, pushing the scope and distension of the intestine caused only mild discomfort to patients. Subsequent shortening of the intestinal tract with a sliding tube was also easily accomplished. In our study, SBE permitted total colonoscopy in all patients with a history of difficulty in colonoscope insertion. There were no serious complications associated with colonoscope insertion or endoscopic treatment. Eight patients (53%) underwent repeated examinations, and total colonoscopy was successfully accomplished at all sessions, confirming that SBE is consistently effective. During SBE, the mean time required for scope insertion into the cecum was 22.9 min. This prolonged insertion time was attributed to the extra time required for insertion of a sliding tube and shortening of the intestine.
Balloon endoscopy has previously been reported to be useful for colonoscopy in patients with a history of difficulty in colonoscope insertion[16
]. Most studies used a DBE, but two studies conducted in the United State and Holland reported the results of SBE[22
] randomly assigned 30 patients with a history of difficulty in colonoscope insertion to undergo SBE or conventional colonoscopy. The success rate of total colonoscopy was significantly higher in the SBE group (93%) than in the conventional colonoscopy group (50%), with no examination-related complications. Teshima et al[23
] reported that total colonoscopy was successfully accomplished in 22 (96%) of 23 sessions of SBE performed in 22 patients with a history of difficulty in colonoscope insertion. In contrast to DBE, SBE does not require a balloon attached to the tip of the scope. Consequently, intestinal gripping strength might be lower with SBE than with DBE. However, our results suggest that SBE with only one balloon attached to the sliding tube was able to adequately shorten the large intestine, allowing total colonoscopy to be successfully accomplished.
Because SBE does not require attachment of a balloon to the scope tip, the preparation time is shorter and insertion of the scope is easier than with DBE. One study reported that the single-balloon technique performed with a DBE, in which a balloon was attached only to the overtube, facilitated scope insertion in patients in whom a colonoscope had been technically difficult to insert[17
]. DBE with a short effective length of 1520 mm are now available and have been reported to be useful[21
In addition to diagnostic procedures such as biopsy, SBE allowed colorectal polyps to be endoscopically resected with no problems or complications. In contrast to a standard colonoscope, the opening of the forceps channel of SBE is located in the 8 o’clock direction. The field of vision is thus similar to that during upper gastrointestinal endoscopy. Because the scope is long, twisting maneuvers applied by the operator are sometimes not transmitted to the scope tip, making it difficult to accurately position endoscopic devices relative to target lesions. Because the forceps channel diameter was 2.8 mm, which is smaller than that of a standard colonoscope, it was difficult to aspirate intestinal juice and air after the insertion of endoscopic devices. Many lesions located at curvatures of the large intestine or on the proximal sides of folds were difficult to view endoscopically. When the intestine was shortened with the use of a sliding tube, the region surrounding lesions was straightened, facilitating lesion inspection as well as endoscopic therapy.
Our results showed that SBE facilitated total colonoscopy in patients in whom scope passage was difficult, confirming that SBE is useful and safe in Japanese subjects. However, this was a retrospective study in a small number of patients, and 1 endoscopist with many years of experience in colonoscopy performed most of the examinations. To clarify whether the technical ability of the operator affects the performance of SBE, prospective studies performed by endoscopists with different levels of experience are needed.