The Effect of Endoscope Water Pump Flow Rates on Successful Unsedated Colonoscopy by Water Immersion Method: a Randomized Controlled Trial

Inclusion Criteria: * Adult \> 18 years old with indication for colonoscopy, such as chronic diarrhea, chronic constipation, hematochezia, chronic lower abdominal pain, positive fecal occult blood test, and other change of bowel habit symptoms indicative of need for diagnostic colonoscopy examination Exclusion Criteria: * Patients refuse to participate, patient with obstructive lesion in the colon distal of the cecum, patients with experienced of colon resection, hemodynamically unstable, severe cardiac disorders (such as acute myocardial infarction, unstable angina, malignant arrhythmia, and moderate to severe congestive heart failure), patients with fecal obstruction (whatever the causes) so that impossible to pass the scope through the obstructed segment.