Constipation is a common reason of poor bowel preparation, which negatively influences the quality of colonoscopy. Clinically to explore more effective and tolerant bowel clearance programs is necessary for patients with chronic constipation.

Colonoscopy is an important method to screen, diagnose and treat colon lesions. The quality of bowel preparation is requisite for the accuracy of diagnosis and safety of treatment. To explore the application effect and safety of Linaclotide combined with Compound Polyethylene Glycol Electrolyte Powder on colon cleansing before colonoscopy in patients with chronic constipation. A prospective mult-centers, colonoscopist-blinded study was conducted. A total of 300 patients with constipation who underwent colonoscopy in 8 hospitals from July to December 2021 were selected as study subjects and divided into the control group, observation group 1, observation group 2 and observation group 3 by random number table method, with 75 cases in each group. Intestinal cleanliness and the incidence of adverse reactions of patients in each group were compared.

Inclusion Criteria:

• Inclusion criteria included: The inclusion criteria were patients ≥18 years old suffering from≥2 of the following criteria of chronic constipation under the Rome IV standard: straining, hard stool, residual stool feeling, occlusion feeling, manual bowel movement(BM) performed ≥25% of overall BMs, and BM frequency<3 times a week . A chronic status was defined as symptoms being present for at least six months, with the symptoms described above being present for at least three months.

Exclusion Criteria:

• Exclusion criteria included: (1)age <18 or> 75; (2) severe chronic renal failure, severe congestive heart failure and Liver dysfunction ;(3)with uncontrolled hypertension, diabetes, intestinal obstruction, intestinal perforation and electrolyte disorders, inflammatory intestinal disease and other organic gastrointestinal diseases;(4)with neurologic, endocrine, or metabolic disorders;(5)treatment with other gastrointestinal drivers, laxatives, and antilaxatives within nearly 2 weeks;(6)history of colorectal surgery;(7) dysphagia; (8) compromised swallowing reflex or mental status;(9)with consciousness disorders or examination intolerance;(10)pregnancy or lactation;(11)allergic to the drug composition;(12)Suspected history of alcohol or substance abuse; (13)Recent participants in clinical trials; (14) unable to give informed consent.