To evaluate whether oral sulfate solution administered in a short time interval (6-8 hours) between the first and last dose of laxative is not inferior to a long time interval (10-12 hours) in bowel preparation quality.

The split-dose bowel preparation is recommended by multiple guidelines and widely used worldwide for improved bowel preparation quality, higher detection rate of colorectal lesions, and better tolerance. The effect of the time interval between the last dose of laxative and the colonoscopy on the quality of bowel preparation has been well studied, but the impact of the time interval between the first and last dose of laxative on the bowel preparation quality deserve to be explored. Oral sulfate solution administered in a short time interval can reduce sleep disturbance and hunger and is more flexible and convenient. This study aims to evaluate whether oral sulfate solution administered in a short time interval (6-8 hours) is not inferior to a long time interval (10-12 hours) on bowel preparation quality.

Inclusion Criteria:

• Voluntarily participate and sign informed consent;
• Subjects who require screening, surveillance, and diagnostic colonoscopy;
• Subjects who take the oral sulfate solution for bowel preparation.

Exclusion Criteria:

• Subjects with serious cardiac and cerebrovascular diseases, bronchial and lung diseases, suffering from metabolic disease or endocrine disease, abnormal blood clotting mechanism, malignant tumor, electrolyte abnormalities, epilepsy, renal or liver dysfunction;
• Subjects with ascites, suspected electrolyte abnormalities, or uncorrected dehydration.
• Subjects with confirmed or suspected gastrointestinal obstruction, gastric retention, gastroparesis, gastric emptying disorder, or acute gastrointestinal bleeding;
• Subjects with confirmed or suspected colorectal cancer, inflammatory bowel disease, toxic colitis, or toxic megacolon.
• Subjects who had previously undergone colorectal resection.
• Subjects with constipation or suspected severe gastric motility disorder;
• Women with positive pregnancy tests or pregnancy plans, and women in lactation;
• Subjects who have participated in any other clinical trials within the last 3 months;
• Subjects with any other conditions that the investigator considered inappropriate for inclusion.