Left-colon WEC May Reduce Insertion Time Compared With Whole-colon WEC.

In most of situation, left colon (especially SD junction) is considered the most difficult part of colonoscopy, where endoscopist may encounter difficulty for scope insertion and patients may feel pain or uncomfortable. It is suggested more than half of the whole time for scope insertion should be used in left colon. Many methods, such as water immersion, abdominal palpation, have been used to facilitate insertion in left colon.

Colonoscopy with whole-colon water exchange method has been shown to be useful for reducing medication used, pain experienced during colonoscopy, increasing the success rate of cecum intubation and adenoma detection rate in sedated and unsedated patients undergoing screening colonoscopy. Exchange of water during scope insertion minimizes loop formation and prevents lengthening and distension of the colon during colonoscopy. This will facilitate the colonoscopy in average or difficult colonoscopy. However, it is not known whether the benefits of water exchange method of colonoscopy was mainly due to its effect on the left colon.

We hypothesized that left-colon water exchange colonoscopy (LWE) may have the similar effect regarding the maximal pain score and mean pain score in unsedated patients compared with whole-colon water exchange colonoscopy (WWE). At the mean time, LWE may reduce the insertion time compared with WWE. Here we performed a prospective, randomized controlled study to investigate the efficacies of whole-colon water exchange, left-colon water exchange and air methods of colonoscopy on pain score and insertion time in unsedated outpatients.