Enhanced instructions such as re-education by telephone or short message which increase the patient adherence eventually improve the quality of bowel preparation significantly. However, the effect of family assistance which plays an essential role on compliance of patient with treatment on bowel preparation is unknown. The investigators hypothesized that reinforced education giving family members of outpatients will enhance family support to patients for colonoscopy, and consequently improve the quality of bowel preparation.

Therefore, the investigators designed protocols to reinforce family member education by verbal (face to face or telephone) and written methods. The aim of this study is to evaluate the effect of reinforced family member education on patient compliance and the quality of bowel preparation for colonoscopy. In addition，the rate of side effects happening, the subjective feelings of bowel preparation, the outcomes of colonoscopy ,and the independent risk factors will be also assessed.

Adequate bowel preparation is essential for optimal examination of the colorectal mucosa during colonoscopy. However, approximately 10%-30% bowel preparation is inadequate, leading to significantly decrease diagnostic accuracy and surveillance intervals, increase the procedural difficulties, and even increase the procedure-related complications. As reported, enhanced instructions such as re-education by telephone or short message which increase the patient adherence eventually improve the quality of bowel preparation significantly. However, the effect of family assistance which plays an essential role on compliance of patient with treatment on bowel preparation is unknown. The investigators hypothesized that reinforced education giving family members of outpatients will enhance family support to patients for colonoscopy, and consequently improve the quality of bowel preparation.

Therefore, the investigators designed protocols to reinforce family member education by verbal (face to face or telephone) and written methods. The aim of this study is to evaluate the effect of reinforced family member education on patient compliance and the quality of bowel preparation for colonoscopy. In addition，the rate of side effects happening, the subjective feelings of bowel preparation, the outcomes of colonoscopy ,and the independent risk factors will be also assessed.

This is a prospective, endoscopist-blinded, randomized, controlled study.

1. Patients, Arm Description, Education and Blinding. Consecutive individuals over 18 years, who will be scheduled for undergoing colonoscopy between September and December 2017 at the Endoscopy Center of Wuxi people's Hospital in China and are not accord with the exclusion criteria will be enrolled in the study. After signature of informed consent, Patients will be consecutively randomized to either the reinforced family member education (RFME) or regular education (control) group at the time of colonoscopy appointments by opening a sealed opaque envelope. Regular instructions will be given to all patients during the colonoscopy appointment by one experienced endoscopy nurse. For RFME group, at least one family member who lives with the patient together will be given instruction at the basis of patent education. The information of group assignments will be keep from colonoscopists and other investigators at any time.
2. Bowel preparation. Two kinds of purgatives, magnesium sulphate and polyethylene glycol electrolyte powder (PEG-ELP), are available in our endoscopy center, and the type will be prescribed by physician based on the conditions of the patient.
3. Data collection and Definitions. On the day of colonoscopy, the patients will be asked to arrive at the Endoscopy Center 1 h before the procedure. The baseline data, clinical data and related data of the enrolled patients will be collected 1 h before the colonosc0py.
4. Colonoscopy. All colonoscopy will be carried out between 13:30 and 16:30 by 5 five experienced endoscopists. The Boston Bowel Preparation Scale (BBPS) scoring system will be employed for the assessment of the quality of bowel preparation. The endoscopists will be asked to give the BBPS score immediately after the colonoscopy, and the findings of the colonoscopy, the cecal intubation, the insertion time, the withdrawal time and the incomplete examination cases not for poor bowel preparation will be recorded simultaneously.
5. Statistical analysis. A total of 276 patients in each group will be required to obtain statistical significance for the primary outcome. Baseline characteristics, primary and secondary outcomes will be evaluated by intention-to-treat (ITT) analysis. To assess independent risk factors associated with inadequate bowel preparation, multivariate analysis will be conducted using the score of bowel preparation quality (BBPS <5) with a P value of ≤ 0.10 in the univariate analysis. All analyses will be carried out with SPSS software V.20.0 (SPSS Inc., Chicago, IL, USA). A P value of <0.05 was considered statistically significant.

Inclusion Criteria:

1. Individuals scheduled for undergoing colonoscopy at the Endoscopy Center of Wuxi people's Hospital in China
2. Greater than the age of 18
3. Individuals living with other family members
4. Outpatients

Exclusion criteria:

1. History of colorectal surgery
2. Suspected or known digestive tract obstruction, stricture, or perforation
3. Serious status of illness, such as severe renal failure whose creatinine clearance<30 ml/min, New York Heart Association grade III or grade IV congestive heart failure, or hemodynamic instability, etc.
4. Incapable of completing bowel preparation，such as dysphagia, allergy to purgatives, or impaired mental status, etc.
5. Pregnancy or breastfeeding
6. Incomplete colonoscopy due to causes except poor bowel preparation
7. Unable to give informed consent
8. Have participated in the study before.

The patients and the associated family members know which group they are assigned，while the colonoscopist, information collector are blinded to group assignment.