Comparison of Oral Lactulose Versus Polyethylene Glycol for Bowel Preparation in Low-risk Patients

Adequate quality of bowel preparation(BP) is essential for colonoscopy. In recently, Kang suggested that for low-risk patients, single dose of 2L PEG is an effective regimen for bowel preparation.However, due to the poor palatability, there still more than 30% patients with 2L regimen experienced nausea or vomiting in our center. Oral lactulose is a treatment for constipation. Several studies have compared the effectiveness between use PEG and lactulose for colonoscopy preparation in average-risk patients. However, the data in low-risk patients is vacant. The objective of current study was to compared the effectiveness of bowel preparation and patient tolerance using lactulose and 2L PEG regimen in low-risk patients.

In the LOS group, patients were instructed to drink 200ml lactulose (Duphalac, Olst, the Netherlands; 200ml/bottle) diluted with clear water into 1L 4-6h before colonoscopy at a rate of 250ml every 30min.

patient in the PEG group were instructed to drink 2L of PEG (each liter containing 59g PEG 4000, 1.46g sodium chloride, 5.68g sodium sulfate, 0.74g potassium chloride, 1.68g sodium bicarbonate; WanHe Pharmaceutical Co, Ltd., China) 4-6h before colonoscopy at a rate of 250ml every 15min

Boston bowel preparation score (BBPS)：cleanliness of each part of the colon: 0=unprepared colon segment with mucosa not seen because of solid stool that cannot be cleared; 1=portion of mucosa of the colon segment seen, but other areas of the colon segment not well seen because of staining, residual stool, and/or opaque liquid; 2=minor amount of residual staining, small fragments of stool and/or opaque liquid, but mucosa of colon segment seen well; 3=entire mucosa of colon segment seen well with no residual staining, small fragments of stool, or opaque liquid.

We will ask patients in the form of questionnaire whether they are willing to repeat the same bowel preparation method if they need colonoscopy examination again

Inclusion Criteria: Patients over 18 years old and with low-risk were eligible. Patients were considered as low risk if they did not meet any of the following risk factors: age>70 years old, body mass index (BMI)>25Kg/m2, constipation, Parkinson's disease, diabetes, history of stroke or spinal cord injury, use of tricyclic antidepressant or narcotics. Exclusion Criteria: (1) history of colorectal resection; (2) Known or suspected colonic stricture or obstructing tumor; (3) Known or suspected colonic perforation; (4) toxic colitis or megacolon; (5) use of prokinetic agents or purgatives within 7 days; (6) hemodynamic instability; (7) pregnancy or lactation; (8) inability to provide informed consent.