The present study shows that the 2L PEG-based bowel preparation is not superior to the 12-hour overnight fast strategy in improvement of diagnostic yield and did not show any advantage with regard to rebleeding rate in patients undergoing SBCE for active suspected overt SBB, although the VQ of small bowel is enhanced and SBTT is shorter with PEG used.
Several studies have illustrated the high sensitivity and specificity of SBCE for detecting overt small-bowel bleeding sources compared to other techniques such as push enterostomy, CT angiography or intraoperative enterostomy, making SBCE the test of choice in the evaluation of small bowel bleeding after high quality upper and lower endoscopic examinations.17–19 Poor bowel preparation with numerous residues such as blisters, bile, intraluminal fluid and debris, may impair the SBCE diagnostic yield and lead to incomplete capsule procedures.2,20 Most current guidelines recommended bowel preparation before the CE exam, although in low-quality evidence due to conflicting data.2,5,21 However, several recent meta-analyses investigating small bowel preparation utility studies or randomized controlled trials have challenged the benefits of purgatives in diagnostic yield, but conflict in improvement of small bowel visualization.22–24 Moreover, overt bleeding is most strongly associated with better diagnosis yields for suspected SSB, whereas occult bleeding is moderate.25 Bowel preparation is less tolerated and reported several side effects such as nausea, bloating, and abdominal pain.26 Therefore, for patients with active overt suspected SSB in ICU, the exact impact of different bowel preparation in diagnostic yield must be confirmed.
According to our results, theovernight fast only regimen seemed to shows no significant difference on the detection of lesions, diagnostic yield or diagnostic accuracy. Our findings are therefore consistent with recent RCTs evaluating the clinical effectiveness of PEG-based regimens and clear-fluid alone in patients with suspected small bowel bleeding.11,12 Commonly, the term “diagnostic accuracy” frequently used in clinical research, such as sensitivity, specificity etc., is replaced by “diagnostic yield” for the lack of further examinations to serve as reliable gold standard, which is a general methodological problem in SBCE studies.27 It is tough to assess a precise association between positive lesion findings and bleeding etiology. Small bowel mucosal lesions were detected in approximately 10% of the recruited healthy subjects28, and the American College of Gastroenterology (ACG) recommended not every small vascular lesion found on the SBCE required treatment when no bleeding origin was identified, although in very low-level evidence.1 Therefore, we attempted to define CE findings associated with excessive risk of bleeding as the final diagnosis of suspected overt SSB by attending gastroenterologist’s interpretation. Causes of small bowel bleeding as listed in the ACG clinical guidelines.1 A positive SBCE diagnosis is classified as true positive or false positive, depending on whether it is confirmed by surgery or other alternative means, or if other, more relative, sources of bleeding are found. Among the two groups, the overall diagnostic yield of SBCE in two groups show no significant variety (47.6% vs. 51.3%; P = 0.719), the same as the sensitivity (53.6% vs. 58.8%) and specificity (71.4% vs. 100%).
The results of the study show that purgatives improve VQ and shorter SBTT, but is not significantly better in terms of CECR. It is widely aware that poor visualization quality may minimize diagnostic yield, and slower SBTT may result in incomplete capsule studies due to capsule battery life constraints, which seems to contradict our study.7 However, for the detection of active suspected overt SBB, the apparent bleeding would be detectable under an overnight fast only strategy, whereas a small or intermittent bleed lesion might be washed out by radical bowel preparation.29,30 It is possible that extra lesion findings from using the PEG regimen prior to CE do not appear to provide any added benefit in terms of final diagnostic yield. Moreover, while purgatives utility shows a shorter SBTT, it does not show a difference in terms of CECR. In general, a 12-hour capsule battery life would be sufficient for small-bowel capsules to throughout the entire intestine after an overnight fast only preparation. We suspect that a longer visible duration might presumably facilitate the avoidance of neglect and omission in mucosal inspection.31
Additionally, the study did not demonstrate a significant difference in rate of transfusion requirement, recurrent bleeding, or mortality between the 2 groups. A previous study has shown that rebleeding are more possible occur in patients with positive CE findings, patients aged ≥ 60 years, Hb level ≤ 70 g/L, receiving nonspecific treatments and use of anticoagulant, antiplatelet agents or NSAIDs after CE.32 We did not find any association between the purgatives use and the clinical outcomes. Apart from the improvement in the quality of visualization of the small bowel, we should perhaps be more concerned about whether a PEG-based preparation of the small bowel might be beneficial for clinical outcomes and patients. There are consecutive evidences that earlier use of capsule endoscopy (immediately or within 48 hours) would propitiate better identification conditions for the bleeding source33–35. Besides, unlike other indications, the first general management of gastrointestinal bleeding is fasting, which means when patients undergo SBCE, some of them are fasting for more than 12 hours. All this minimizes the necessity for the use of purgatives.
Our study does have several limitations. As a retrospective study, selection bias could not be excluded and randomization was not possible. What’s more, it is unusual to find patients in ICU with active suspected overt SBB, so the sample size was relatively small. Lastly, in spite of extensive further examination, the gold standard for the origin of bleeding remains absent, and some bleeding etiologies have failed to be validated. Therefore, a larger, multicenter, randomized studies are needed to confirm our findings.
In conclusion, this is a retrospective study that compares 2 L of PEG solution with a fasting only strategy in patients performing SBCE for active suspected overt SBB. 2L PEG-based bowel preparation did not result in improvement of diagnostic yield or clinical outcomes, although the VQ of small bowel is enhanced. With less discomfort and side effects, fasting may be preferred over the use of PEG solutions in patients with active overt suspected SBB.