Small bowel cleansing for capsule endoscopy, systematic review and meta- analysis: Timing is the real issue

Background: The optimal small bowel preparation modality before capsule endoscopy (SBCE) is still uncertain, regarding preparation type, dose and timing of administration. Aim: The aim of the study is to evaluate the small bowel cleansing in patients undergoing small bowel capsule endoscopy after fasting alone or active treatment with purgative solutions. Methods: We searched 4 major scientific databases from inception to December 2021 for studies evaluating small bowel preparation before SBCE. Different preparation efficacy was compared using fasting as reference. Main variables evaluated in the current study were: preparation type, administration schedule and timing. Results: 17 studies (27 treatment arms) with 2372 patients (male 47,4%) were included, mean age 54 years. Fasting alone VS overall purgative preparations pooled rate difference (RD) was 0.15 I2=81.5% p: 0.000. Sub-analysis for preparation schedule (day-before, split and same-day) and the time lapse showed that administration of PEG after the ingestion of capsule had the highest rate of adequate small bowel cleansing with a RD 0.33, administration between 1 and 6 h before SBCE had a RD 0.28, 6 to 12 h had a RD 0.21 and ≥12 h had a RD 0.05. Conclusions: Timing of ingestion was found to be critical for bowel cleansing; the shorter time laps between the ingestion last dose of laxative and SBCE, the better was the mucosal visualization.