The aim of this study was to investigate the effect of different bowel preparation protocols applied on the same day on patients' compliance, tolerance and bowel cleansing before colonoscopy.

Hypotheses of the Study : Same-day administration of bowel preparation before colonoscopy; H1.1: There is a significant difference between the bowel preparation protocol with polyethylene glycol (Protocol I) and the protocol with sodium phosphate (Protocol II) in bowel preparation score scores H1.2: There is a significant difference between the compliance levels of the patients who underwent a bowel preparation protocol containing polyethylene glycol (Protocol I) and a protocol containing sodium phosphate (Protocol II) H1.3: There is a significant difference between the tolerance of the patients who underwent a bowel preparation protocol containing polyethylene glycol (Protocol I) and a protocol containing sodium phosphate (Protocol II)

In patients in Protocol I and II groups, data will be collected one day before the procedure with the Descriptive Characteristics Form and the procedure will be explained face to face. After the procedure, bowel preparation score during colonoscopy and compliance and tolerance to the bowel preparation protocol will be evaluated from the patients in both groups.

The aim of this study was to investigate the effect of different bowel preparation protocols applied on the same day on patients' compliance, tolerance and bowel cleansing before colonoscopy.

This study will be conducted as a single centre prospective randomised controlled trial in accordance with the principles of the Declaration of Helsinki. The study will be conducted in a private clinic in Famagusta region in patients undergoing colonoscopy.

Patients undergoing colonoscopy will be given written material about bowel preparation the day before the procedure and the protocol will be explained verbally and in writing. The bowel preparation protocol is described below.

Protocol I 06.30 Breakfast 09.00 hours: Phospho-Soda 45 ml 10.00: Phospho-Soda 45 ml At least 3 litres of liguid fluid intake until 14.00 14.30- 15.00: Colonoscopy Protocol II 06.30 Breakfast 09.00 :Polyethylene Glycol (PEG) will be diluted with 4 litres of water and one glass (200ml) will be drunk every 10 minutes until it is finished (It will be finished in about 4 hours) Colonoscopy after 2 hours Inclusion criteria

• Over 18 years of age
• Drinking at least 75 per cent of the solution
• Have the ability to read and understand research instructions
• Patients who agreed to participate in the study Sampling exclusion criteria
• Patients with active lower intestinal bleeding Patients diagnosed with CHF, liver failure, end-stage acute renal failure

A total of 118 patients were planned to be included in the study with an effect size of d=0.50, α =0.05 margin of error, 85% power, and 59 patients in each group. Considering the possibility of missing data, the sample number was increased by 10% and it was decided to take 128 patients by taking 64 patients in the groups in total.

The patients will be assigned to the experimental and control groups according to the list to be created using the randomisation program at a ratio of 1.1(https://www.random.org/). Randomisation and assignment to groups will be done by an independent researcher who is not involved in the implementation phase of the research. Thus, selection bias will be prevented in the randomization process.

In patients in Protocol I and II groups, data will be collected one day before the procedure with the Descriptive Characteristics Form and the procedure will be explained face to face. After the procedure, the bowel preparation score during colonoscopy and compliance and tolerance to the bowel preparation protocol will be evaluated from the patients in both groups.

Inclusion Criteria:

• Drinking at least 75 per cent of the solution
• Have the ability to read and understand research instructions
• Patients who agreed to participate in the study

Exclusion Criteria:

• Patients with active lower intestinal bleeding
• KKY
• Liver failure,
• Patients with end-stage acute renal failure

The statistician will not know which group the intervention is for. Data entry will be made as A and B.