A Pre-endoscopic Prediction Model for Inadequate Bowel Preparation in Patients Receiving Split Dose Polyethylene Glycol Preparation

After written consent for participating in clinical research studies, all clinical studies conducted to in the one day. The investigators will ask and record about bowel cleansing state in all patients who performed colonoscopy. There is no additional cost and the expected complications. Based on answer, the investigators will develop a prediction model for inadequate bowel preparation and prove validation. This model can take the additional measures to subjects predicting improper cleansing. It can contribute to improve the accuracy of the test and reduce the discomfort due to re-performing colonoscopy after re-preparation, as well as cost savings due to reduced frequency of re-colonoscopy Ultimately, it will be able to bring a improvement of the quality of management