Small bowel video capsule endoscopy (SBCE) has evolved to be an important tool in the investigation of the small bowel 1. The main indications for its use are occult gastrointestinal bleeding, suspected small bowel Crohn’s disease, suspected small bowel tumor, evaluation of abnormal small bowel imaging, small bowel surveillance in inherited polyposis syndrome, partially responsive celiac disease, and medication-related small bowel injury 2–8.
SBCE is a well tolerated, noninvasive, and ambulatory procedure. The patients are put on clear liquids the day before the procedure and swallow the capsule with water after a 12 h fast. Drinking of clear fluids is allowed 2 h after ingestion as is a light lunch after 4 h. Therefore, the gastric passage of the capsule is in a fasting state. Usually, the capsule remains in the stomach up to 45 min before moving down to the duodenum 9,10. In these studies, which included 195 patients who underwent SBCE examination, the mean gastric passage interval was 37–42 min.
Prolonged gastric transit in not uncommon in SBCE studies, and can indicate a possible gastric motility disorder, thus disrupting whole small bowel visualization because of termination of the capsule battery before completing small bowel passage. To the best of our knowledge, no data on the clinical significance of prolonged SBCE gastric transit time have been published. The aim of our study was to prospectively examine the association of prolonged gastric passage interval with symptoms, anthropometric and laboratory factors as well as with factors related to the SBCE examination, such as indications and pathological findings.
Materials and methods
This prospective study was carried out between January 2012 and April 2013 in the Gastroenterology Department at the Chaim Sheba Medical Center (Ramat Gan, Israel). Our department serves as a tertiary referral center for SBCE studies for the central part of Israel. In this study, we included all patients aged at least 18 years who were referred for ambulatory SBCE for any indication. Exclusion criteria included endoscopic insertion of the capsule because of previous failure of capsule passage to the stomach or to the duodenum and esophageal capsule retention. Our main outcome was the interval of the SBCE gastric transit. To include only significant cases in the prolonged gastric passage interval group, we set the cutoff of ‘normal’ or ‘possibly normal’ gastric passage to less than 45 min. This cutoff was based on the results of two published studies that included 195 patients and described a mean SBCE gastric passage interval of 37–42 min 9–10. The rate of prolonged gastric capsule passage time (≥45 min) in our previous observations was 25%. Sample size calculation estimated that to detect a difference of 0.5 in the mean Gastroparesis Cardinal Symptoms Index (GCSI) between the two groups (two-sided α=0.05 and 1−β=0.8, assuming pooled variance=0.60, ratio A : B=3), a total sample of 100 participants (25 in the prolonged gastric passage group and 75 in the normal gastric passage group) was required. To examine the possible effects of an even longer gastric passage interval, we carried out a subanalysis using a cutoff of 80 min, as described by Iddan et al. 11. The study was approved by the Institutional Helsinki Committee (Sheba-9180-2011) and was registered at ClinicalTrials.gov as NCT01858220.
Small bowel video capsule endoscopy
A PillCam SB2 video capsule endoscope was used in our study (Given Imaging, Yokneam, Israel). This is a wireless capsule (11×26 mm) with a slippery coating that allows easy ingestion and prevents adhesion of bowel contents while the capsule moves through peristalsis from the mouth to the anus. It photographs two images per second in a 156° field of view and 8 : 1 magnification. Patients were instructed to be on clear liquids the day before the procedure and fast for 12 h before the examination. Before the examination, after signing an informed consent, the patients were examined by a gastroenterologist and a nurse, and data on indication for the examination, medical history, use of medications, laboratory results (hemoglobin, C-reactive protein, and albumin), and anthropometric data were recorded. Following this, the patients filled the GCSI score questionnaire and swallowed the capsule with 100 ml of clear water. Drinking of clear fluids was allowed 2 h after ingestion as was a light lunch after 4 h. During the procedure, the patients were free to do their daily activities. The pictures were transmitted by an eight-lead sensor array, attached in a specific manner on the patient’s belly, to a small recorder. The procedure was stopped when the battery ceased working. On the next day, the recorder was downloaded into a Reporting and Processing of Images and Data computer workstation (RAPID 7; Given Imaging) and seen as a continuous video film by one of four experienced gastroenterologists (>200 capsule readings). Esophageal passage interval was calculated as the time from the capsule swallowing and until the first gastric image. Gastric passage interval was calculated from the first gastric image and until the first duodenal image. Small bowel passage interval was calculated from the first duodenum image and until the first cecal image. The first gastric, first duodenal, and first cecal images were recorded. Any pathology that was observed was included in the final report and recorded by the examiners.
Gastroparesis Cardinal Symptoms Index
The GCSI introduced in 2004 by Revicki and colleagues is an effective tool for assessment of the severity of symptoms associated with gastroparesis 12,13. The GCSI consists of nine symptom severity items, which cover the following domains: nausea/vomiting, fullness/early satiety, and bloating. Symptoms are rated by the patients from none (0) to very severe (5). As gastroparesis may involve a number of symptoms, some of which might represent different functions of the stomach, every question was assessed on its own.
The characteristics of the participants are presented as means±SD, or counts in the case of categorical variables. t-Test was used to compare the mean difference in age, BMI, hemoglobin, and albumin between the gastric passage groups (<45 vs. ≥45 min). The GCSI results were compared between the gastric passage groups using the Mann–Whitney test and Fisher’s exact test when results were dichotomized as 0 and more than 0. Fisher’s exact test was also used to evaluate the association between the prevalence of diseases or other indications and gastric passage groups (2×2 tables). Pearson’s correlation was calculated for gastric and the small bowel passage intervals. Two-sided P value less than 0.05 was considered statistically significant. Analyses were carried out using IBM SPSS version 21 (IBM, New York, New York, USA).
One hundred patients were included in this study. Seventy-six patients had normal gastric transit interval (<45 min) and 24 patients had prolonged gastric transit interval (≥45 min). Three patients were excluded: one because of capsule retention in the pharynx and two because of endoscopic after pyloric capsule insertion. None of the patients had undergone a previous gastric operation. There was no capsule retention or any adverse events reported in both groups. The capsule reached the cecum while photographing in 95% of the patients. No significant differences were found between the patients with normal gastric transit interval and prolonged gastric transit interval regarding age, sex, prevalence of diabetes mellitus, use of antimotility drugs, indications for the exam or levels of hemoglobin, C-reactive protein, and albumin (Table 1). The interval of esophageal capsule transit was not significantly different in patients with normal and prolonged gastric transit interval (mean of 0.4 min in both groups, P=0.70). Small bowel transit interval was not significantly different between both groups (247±118 vs. 237±104 min, P=0.72, normal and prolonged passage interval, correspondingly), as well as the overall rates of complete small bowel examination (94.5 vs. 95.6%, P=0.66, gastric passage interval <45 and ≥45 min, correspondingly). There was no association between gastric and the small bowel transit intervals (r2=−0.062, P=0.542).
The mean score for any GCSI item and the mean total GSCI score did not differ significantly between the normal and the prolonged gastric passage interval groups (Table 2). Moreover, comparison of only abnormal GCSI item scores (i.e. any item≥1) did not vary significantly between the two study groups (Table 3).
Finally, we did not find any significant difference between any pathological findings in the small bowel and gastric transit time (normal or prolonged) (Table 4). No significant pathology was observed in the stomach in any patient.
In a subanalysis carried out with a prolonged cutoff of 80 min, no significant differences were found between both study groups in the mean total GSCI score (P=0.74), the only abnormal GCSI item scores (P=0.31), and in the rate of the diagnosis of any pathology (P=0.86).
To the best of our knowledge, this is the first study to examine the clinical associations that might be attributed to prolonged gastric transition interval of SBCE. The main results of our prospective study show that prolonged duration of SBCE gastric transit had no effect on the clinical symptoms of gastroparesis, as well as on other anthropometric, demographic, and laboratory features. Prolonged gastric passage of SBCE did not affect whole small bowel passage interval and did not disrupt the success rates of whole small bowel visualization (95%), which was higher than reported previously for the Given Imaging small bowel capsule.
Prolonged gastric SBCE transition was observed in a quarter of our study population. Although SBCE has not been used previously for the determination of gastric transit time, a similar tool – the wireless motility capsule (SmartPill; Given Imaging) – has been validated as a useful instrument in the diagnosis of gastroparesis 14. However, prolonged gastric transition had no relation to any clinical symptom of gastroparesis as indicated by the GCSI score. Furthermore, in the prolonged gastric transit group, the mean GCSI scores as well as the mean score for any GSCI item did not reach the mean scores of patients with gastroparesis, as reported previously by Revicki et al. 12. Therefore, it can be assumed that prolonged SBCE gastric transit has no clinical significance in the general population.
There are a few possible explanations for this finding. SBCE transition through the stomach occurs in a fasting gastric state. In this state, electrical and contractile events of the corpus or antrum occur in a highly regular pattern termed the migrating myoelectrical complex (MMC) 15. The three phases of the MMC, as described by changes in intraluminal contractions, recur approximately every 90–120 min. Swallowing of the SBCE after the initiation of the MMC can result in prolonged gastric transition, at least until the recurrence of another MMC cycle. Furthermore, studies examining the effects of promotility agents (such as erythromycin) on SBCE transit times did not find any significant acceleration in the SBCE gastric transition period 9,16. Therefore, it appears that prolonged SBCE gastric transition in a general population does not mandate further gastrointestinal evaluation. Although loss of the antral phase 3 contractions that results in poor emptying of fibrous debris in the stomach was described in diabetic gastroparesis 17, the duration of SBCE gastric duration in patients with documented gastroparesis was not examined in this study and needs further evaluation.
An important factor in achieving satisfying SBCE results is the visualization of the entire small bowel. Up to 20% of the studies were reported to be incomplete, mostly because of slow transit 5. Previous attempts to improve the rate of the completion of the study by adding promotility agents or bowel preparation did not achieve a significant improvement in the rates of whole small bowel visualization 9,18. Interestingly, in our study, prolonged gastric SBCE transition intervals did not reduce the rate of complete small bowel visualization. A possible explanation for this result could be related to a relative reduction in the small bowel transition period, as reported previously in a retrospective study 19. However, in our study, this correlation was not observed. Moreover, in our study, whole small bowel visualization rates were found to be high, reaching close to 95%.
Our study has several limitations. The study was focused on patients’ clinical symptoms and gastric scintigraphy was not performed. However, usually, gastroparesis is diagnosed on the basis of specific symptoms, which can be measured using the GCSI score, as performed in our study. Another limitation is the lack of patients with documented gastroparesis. However, the association of SBCE gastric transit interval with clinical symptoms in this population will be addressed in our future studies.
We found that in the study population, SBCE prolonged gastric transit interval had no clinical significance. Further studies are needed to examine the rate and significance of gastric SBCE transition in patients with established gastroparesis.
Conflicts of interest
There are no conflicts of interest.
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Keywords:Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved.
gastric transit time; gastrointestinal pathologies; PillCam small bowel