Colonoscopy has been used for ages as an evaluating tool of the colonic mucosa for screening and early detection of colonic cancer. Several studies have reported that poor bowel preparation reduces detection of polyps that may have the potential to be cancerous. Polyethylene glycol (PEG) has become the most commonly used agent for colon cleansing because it does not cause fluid exchange across the mucosal membrane and thereby limits fluid and electrolyte disturbances.

Only a few studies have evaluated the effects of different diet types on bowel preparation under controlled circumstances. Various studies were made to find the best pre-colonoscopy diet with no single clear study comparing all 3 dietary regimen together was carried out. So, evidence for the efficacy of a RD (regular diet) in bowel preparation is lacking, which led us to question whether it is reasonable to recommend a RD for 24 hours prior to colonoscopy as part of a PEG-based bowel prepa¬ration in healthy inpatients.

The investigators are proposing to carry out a randomized clinical trial at Makassed General Hospital and include patients from October 2018 till February 2019. The data of 90 stable adult patients will be obtained through patients' interviews.

In the trial, all adult inpatients (range, 18 to 80 years old) undergoing colonoscopy for colorectal cancer (CRC) screening in Makassed General Hospital with nonspecific gastrointestinal symptoms will be candidates for inclusion in the study. Patient receiving endoscopy will be asked to answer multiple questions on the day of procedure. Patients will be randomly allocated to one of 3 groups: Regular Diet (RD), Clear Fluid (CF) and Low-Residue Diet (LRD). The primary outcome will consist of the quality of bowel preparation and efficacy of colon cleansing.

The study will be conducted in Makassed General Hospital (MGH) including all admitted patients receiving colonoscopy for the different indications. All patients will receive low volume 2L alpha peg split preps given 8 hours apart at a rate of 1 cup q 30 minutes with addition of 1 L of pure water post each liter with the addition 10mg of bisacodyl the night before.

In the trial, all adult inpatients (range, 18 to 80 years old) undergoing colonoscopy for CRC screening In MGH or with nonspecific gastrointestinal symptoms will be candidates for inclusion in the study. Exclusion criteria will be as follows: outpatient status; serious medical condi¬tions, such as severe cardiac, renal, liver, or metabolic disease; stroke or dementia; major psychiatric illness; known allergy to polyethylene glycol (PEG); a previous colon resection; incomplete colonoscopy examination (failure of cecal intubation); or functional constipation defined by Rome III diagnostic criteria.

Patient information was collected before procedure which included age, gender, weight, height, body mass index (BMI), indications for colonoscopy, and history of previous operation and colonoscopy, as well as bowel frequency. Patients will complete a questionnaire before colonoscopy regarding their preparation experience (the start and end time for PEG solution ingestion; the amount of PEG solution ingested; any associated adverse effects, includ¬ing abdominal pain, nausea, vomiting, headache, dizziness, and others; and willingness to repeat the same preparation in the future) with the help of an endoscopy nurse who will be blinded to the dietary randomization.

Participants were categorized into subgroups with regard to compliance; good compliance was defined as less than 25% of the PEG solution remaining, and poor compliance was defined as 25% or more of the PEG solution remaining. The subjects were randomly assigned to either eat Regular diet (RD), clear fluid diet (CLD) or low-residue diet (LRD) explained to each randomized case by in-hospital dietitian. In all three groups the offered diet was given at breakfast and lunch with fluids only given at dinner.

Inclusion Criteria:

• inpatients 18 to 75 years old
• undergoing colonoscopy for CRC screening
• with nonspecific gastrointestinal symptoms

Exclusion Criteria:

• outpatient status;
• serious medical conditions, such as severe cardiac, renal, liver, or metabolic disease;
• stroke or dementia;
• major psychiatric illness;
• known allergy to PEG;
• previous colon resection;
• incomplete colonoscopy examination (failure of cecal intubation);
• functional constipation defined by Rome III diagnostic criteria.