BACKGROUND AND AIMSCurrent guidelines recommend bowel preparation before small-bowel capsule endoscopy (SBCE). However, the optimal protocol is yet to be defined. To determine the best timing for preparation in SBCE, we compared small-bowel visualization quality (SBVQ), diagnostic yield (DY), and patient-reported outcomes across 4 purgative regimens.METHODSIn this prospective, randomized (1:1:1:1), multicenter study, patients with suspected small-bowel bleeding were randomized into 4 arms: G1 (1 L of polyethylene glycol + ascorbic acid [Moviprep, Norgine, Amsterdam, Netherlands] the night before SBCE), G2 (1 L in the morning up to 2 hours before SBCE), G3 (0.5 L up to 2 hours before SBCE + 0.5 L after the capsule reached the duodenum), and G4 (1 L after the capsule reached the duodenum). To assess DY, lesions were categorized as having high (P2) or low (P0 or P1) bleeding potential. SBVQ was assessed using the Brotz score. Transit times were measured, and patient tolerability was scored from 0 to 5, with higher scores indicating better tolerability.RESULTSA total of 387 patients were included, 59% female and with a median age of 73 years (interquartile range, 23). The examination completion rate was lower in G1 (90%, P < .001). Small-bowel transit time was shorter for patients receiving purgative during SBCE (G3 and G4, P = .001). SBVQ was better in patients receiving purgative after reaching the small bowel (P < .001): a median of 7 for G1, 8 for G2, and 9 for G3 and G4. The overall DY of patients receiving intraprocedure purgatives (G3 + G4) was superior (42.7 vs 31.3%, P = .02); significant differences were found in the second and third terciles. Likewise, G3 and G4 had higher angioectasia detection (P = .04). Patients' satisfaction was significantly superior for G4 (median, 4 points; interquartile range, 1).CONCLUSIONSThe group that received the bowel preparation the night before SBCE had poorer outcomes. Intraprocedure purgative regimens reduced SBTT, enhanced visualization, improved DY, and increased angioectasia detection. G4 was the best-tolerated regimen.