© Georg Thieme Verlag KG Stuttgart · New York
24 November 2010 (eFirst)
Predictive role of capsule endoscopy on the insertion route of double-balloon enteroscopy (Li X et al., Endoscopy 2009 )
Capsule endoscopy and double-balloon enteroscopy (DBE) have similar diagnostic yields for the evaluation of small-bowel diseases . Some of the unique advantages of capsule endoscopy, such as its less invasive nature, superior tolerability and, in theory, complete visualization of the small-bowel mucosa, dictates that capsule endoscopy is the preferred first-line investigation in patients with suspected small-bowel pathology . However, capsule endoscopy is limited by the inability to perform real-time assessments and biopsy sampling or therapeutic interventions on detected lesions, for which small-bowel enteroscopy is needed. Thus, DBE or single-balloon enteroscopy (SBE) often needs to be performed after capsule endoscopy, guided by the capsule results.
In the majority of patients a combination of oral and anal DBE procedures are used to achieve complete small-bowel visualization. However, it is important to choose the initial insertion route most likely to reach the suspected pathology for reasons of efficiency, patient comfort, and prevention of possible complications. Previous studies have used the relative location of abnormal findings seen on capsule endoscopy to select an initial oral or anal DBE route . In a similar fashion, the study by Li et al.  prospectively evaluated a system of using the relative position of lesions identified by capsule endoscopy within the small bowel to calculate a location index that would then determine the primary route of DBE insertion. The index of lesion location was defined as the time from the pylorus to the lesion as a percentage of the time from the pylorus to the ileocecal valve. The cut-off for the lesion location index used to select the insertion route for DBE was determined from previously collected data from 16 patients. Based on these retrospective data, a location index of ≤ 0.6 was adopted to select an initial oral approach and > 0.6 for an initial anal approach; this was then prospectively applied to patients with suspected small-bowel diseases who underwent capsule endoscopy (complete to the cecum) followed by DBE.
A total of 82 patients were enrolled in the study. Six (7.3 %) were excluded because lesions seen on capsule endoscopy (all of which were suspected submucosal tumors) could not be confirmed on bi-directional DBE. Another 16 patients (19.5 %) were excluded because the capsule did not reach the cecum by the end of the capsule recording time, so no index could be calculated. Thus, 60 patients remained for comparison of complete capsule endoscopy and DBE findings. In patients who underwent both oral and anal DBE procedures, confirmation of capsule endoscopy findings was defined according to the first DBE procedure performed. The indications for small-bowel investigation were obscure gastrointestinal bleeding (OGIB; n = 40 [67 %]), suspected Crohn’s disease (n = 8 [13 %]), suspicion of small-bowel tumor (n = 5 [8 %]), and unexplained abdominal pain or diarrhea (n = 7 [12 %]). A total of 60 DBE procedures were performed – 41 oral and 19 anal, all of which reached the lesions identified on capsule endoscopy. A large number of patients were found to have small-bowel tumors compared with the number with angiodysplasia, 20 (33 %) and 10 (17 %), respectively, a result not in keeping with findings from OGIB studies that have been performed in Europe and North America but not that surprising given that this study was conducted in East Asia. The diagnosis from DBE was confirmed by subsequent surgery in 42 patients (70 %), with the estimated distance from the pylorus to the lesion of interest differing between DBE and surgery by an average of only 18 cm (range 0 – 50 cm). The mean capsule transit time from the pylorus to the lesion was 125 minutes (± 75) and 276 minutes (± 95), for the oral and anal routes, respectively. Although this represented a statistically significant difference in mean transit times, there was considerable overlap in the capsule transit times between lesions reached by oral and by anal DBE. By contrast, the index of lesion location cut-off of 0.6 successfully predicted the correct route for the initial insertion of DBE with 100 % accuracy and therefore, is a superior prediction method for selecting route of DBE insertion than capsule transit time alone. The authors conclude that capsule endoscopy was incomplete by not reaching the cecum in 19.5 % of procedures, reported false-positive findings in 7.3 % of patients, and had capsule endoscopy findings successfully confirmed by subsequent DBE in the remaining 73 %, for which the optimal route of insertion was correctly predicted in all cases by using the lesion location index.