Prospective controlled study on the effects of polyethylene glycol in capsule endoscopy

To prospectively confirm whether a small amount of polyethylene glycol (PEG) ingested after swallowing endoscopy capsule improves image quality and completion rate.

Forty-four consecutive patients referred to us for capsule endoscopy (CE) were randomized to two groups. All patients were restricted to clear fluids for 12 h before the examination. Patients in group A (22 cases) received no additional preparation, while those in group B (20 cases) ingested 500 mL of PEG within a 2 h period starting 30 min after swallowing the capsule. Clear fluids and meals were allowed 2 h and 4 h after capsule ingestion, respectively. Image quality was assessed as the percentage of visualized bowel surface area as follows: 1: < 25%; 2: 25%-49%; 3: 50%-74%; 4: 75%-89%; 5: > 90%. The small bowel record was divided into five segments by time, and the score for each segment was evaluated. All CE examinations were performed with the Pillcam SB capsule endoscopy system (Given Imaging Co. Ltd., Yoqnem).

This study ended in December 2009, because sample size was considered large enough. A total of 44 patients were enrolled. Two patients in group B were excluded from the analysis because small bowel images could not be obtained from these patients; one had a full stomach, while the other presented with a massive gastric bleed. Thus, 22 patients from group A and 20 patients from group B completed the study. There was no significant difference in age (P = 0.22), sex (P = 0.31), and indication for CE. No significant adverse events occurred in any of the study patients. In group A, image quality deteriorated as the capsule progressed distally. However, in group B, image quality was maintained to the distal small bowel. In each of the five segments, the visibility score was significantly higher in group B than in group A (segment 1: 4.3 ± 0.7 vs 4.7 ± 0.5, P = 0.03; segment 2: 4.2 ± 0.9 vs 4.8 ± 0.4, P = 0.01; segment 3: 4.0 ± 1.0 vs 4.6 ± 0.7, P = 0.04; segment 4: 3.6 ± 1.1 vs 4.5 ± 0.6, P = 0.003; segment 5: 2.7 ± 1.0 vs 4.4 ± 0.8, P = 0.00004). Thus, the use of PEG during CE examination significantly improved image quality in all time segments, and this effect was more pronounced in the distal ileum. The completion rate to the cecum was not significantly different between groups A and B (81.8% vs 85.0%, P = 0.89). There was no difference in the gastric transit time between groups (36.2 ± 35.0 min vs 54.0 ± 56.6 min, P = 0.23), but the small bowel transit time was significantly longer in group A than in group B (246.0 ± 107.0 min vs 171.0 ± 104.0 min, P = 0.04).

The ingestion of a small amount of PEG after the swallowing of an endoscopy capsule significantly improved CE image quality, but did not enhance the completion rate to the cecum.