Water Injection Colonoscopy vs Air Insufflation Colonoscopy in Experienced Endoscopists

Up to now, many studies has showed that compared with air insufflation colonoscopy, water-related colonoscopy could shorten the cecal intubation time and relieve the pain of the patients,especially for training the beginners，the effect was notable, but the present researches on water assisted technique has still been confined to following aspects:1.Water infusing was based on air insufflation; predetermined amount of water was infused ,and water was infused while passing through certain segment of the bowel(such as the left half of colon) ; 2.When training the first-learners, certain dose of sedatives or analgesics was injected; 3.The patients recruited were less. Colonoscopies in this study would be performed by experienced endoscopists of air insufflation colonoscopy, water would be injected completely instead of air insufflation while advancing the colonoscope, the amount of the water infused would not be predetermined but vary from individuals, and all the patients would be examined without any sedatives or analgesics.