Abstract:Objective To investigate the effect of simethicone administration timing on the preparation of oral compound polyethylene glycol electrolyte. Methods A total of 600 patients who underwent colonoscopy were randomly divided into groups A, B, and C, 200 in each group. The three groups were based on compound polyethylene glycol electrolyte 139.12g (2 000 ml) 4 hours before the examination. Group A only took compound polyethylene glycol electrolyte powder, group B took polyethylene glycol electrolyte powder with dimethicone (4h before the examination) and group C took polyethylene glycol electrolyte powder with plus dimethicone (1h before the examination).The intestinal preparation score, colonoscopy bubble score, mirror time, difference in colonoscopy lens clarity and so on were compared among the three groups. Results The gut preparation score (9.35±0.45) in group C was higher than that in group A (7.95±1.22) and group B (8.37±0.36) (P < 0.05); the score of colonoscopy in group C (0.19±0.07) was lower than that in group A (0.45±0.15) and group B (0.30±0.10) (P < 0.05); the time of advance and retreat in group C (8.15±1.20), (9.35±0.60) min was shorter than group A (10.45±1.65), (12.11±0.85) min and group B (9.35±1.22), (10.93±0.60) min (P < 0.05); the colonoscopy lens resolution score (0.78±0.13) in group C was lower than that in group A (1.97±0.26) and group B (1.46±0.35) (P < 0.05). No adverse events occurred in each group during the study. Conclusions Simethicone combined with polyethylene glycol electrolyte can be used as a bowel preparation preparation before enteroscopy. 1 hour before dimethicone examination, it can effectively reduce the amount of air bubbles in the intestine, improve the efficiency of microscopy, and improve the intestinal preparation.