Effect of Simethicone on Colon Preparation During Water Exchange Colonoscopy

June 23, 2026 updated by: Dalin Tzu Chi General Hospital

Effects of Simethicone on Colon Preparation in Water Exchange Colonoscopies: a Randomized Controlled Study

Background: Colonoscopy reduces colorectal cancer mortality by enabling early detection and removal of adenomas. Its effectiveness, however, depends heavily on bowel preparation quality and mucosal visibility. Simethicone, an anti-foaming agent, decreases intraluminal bubbles and improves visualization; studies in conventional air-insufflation colonoscopy generally show benefits for cleanliness and patient comfort, but evidence in water-exchange (WE) colonoscopy remains limited.Objective: To evaluate whether adding oral simethicone to a split-dose polyethylene glycol (PEG) regimen further improves bowel cleanliness and procedural performance in WE colonoscopy.Methods: Adults undergoing outpatient colonoscopy will be randomly assigned (1:1) to a simethicone group or a control group, with a planned enrollment of 180 participants. All procedures will use the WE insertion technique, and endoscopists will be blinded to group allocation. The primary endpoint is the Boston Bowel Preparation Scale (BBPS); adequate preparation is defined as a total score ≥6 with all segment scores ≥2. Secondary endpoints include bubble score and CEBuS, adenoma detection rate (ADR), polyp detection rate (PDR), cecal intubation rate and time, withdrawal time, volume of water used and flushing/irrigation metrics, and patient-reported tolerability and satisfaction.Expected Results: Compared with PEG alone, adding simethicone is expected to (1) increase the proportion of adequate BBPS preparations, (2) reduce bubble coverage, (3) maintain or potentially improve ADR/PDR, and (4) enhance patient tolerability and satisfaction.Conclusion: If effective, this intervention would provide a simple, low-cost strategy to optimize the quality of WE colonoscopy.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

180

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Consecutive patients undergoing screening, surveillance, or diagnostic colonoscopy.
  • Procedures performed by participating endoscopists.
  • Ability to provide written informed consent.

Exclusion Criteria:

  • Colonoscopy performed using air insufflation or water immersion technique.
  • History of colorectal surgery (e.g., colectomy or colostomy).
  • Known or suspected colonic obstruction or severe stricture.
  • Requirement for inpatient bowel preparation.
  • Known allergy or hypersensitivity to simethicone.
  • Unable or unwilling to provide informed consent.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Health Services Research
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: Without simethicone group
follow a bowel preparation protocol consisting of 10 mg of bisacodyl and 2 liters of PEG solution.
Drug: PEG
All participants followed a standardized bowel preparation protocol consisting of 10 mg of bisacodyl and 2 liters of PEG solution administered in a split-dose regimen.
Experimental: With simethicone group
Participants received a total of 30 mL of simethicone, with 15 mL added to each 1-liter dose of polyethylene glycol (PEG) solution in the split-dose regimen.
Drug: Simethicone with PEG
All participants followed a standardized bowel preparation protocol consisting of 10 mg of bisacodyl and 2 liters of PEG solution administered in a split-dose regimen. Participants in the simethicone group additionally received 30 mL of simethicone (600 mg), with 15 mL added to each 1-liter dose of PEG solution.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Boston bowel preparation scale (BBPS)
Time Frame: At the time of colonoscopy.
Bowel preparation quality assessed using the Boston Bowel Preparation Scale (BBPS). Adequate preparation is defined as a total score ≥6 with all segment scores ≥2.
At the time of colonoscopy.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Bubble score assessed using a 4-point bubble scale
Time Frame: During the colonoscopy procedure.
Bubble score assessed during colonoscopy using a 4-point scale (0-3) for each colon segment, where higher scores indicate more bubbles.
During the colonoscopy procedure.
Colon Endoscopic Bubble Scale(CEBuS)
Time Frame: During the colonoscopy procedure.
Bowel cleanliness assessed using the Colon Endoscopic Bubble Scale (CEBuS), categorized based on the percentage of mucosal surface obscured by bubbles (e.g., <5%, 5-50%, >50%).Higher scores indicate poorer visibility due to bubbles.
During the colonoscopy procedure.
Adenoma detection rate (ADR)
Time Frame: one week
one week
Polyp detection rate (PDR)
Time Frame: one week
one week
Cecal intubation rate
Time Frame: At the time of colonoscopy.
Proportion of procedures in which the cecum is successfully reached.
At the time of colonoscopy.
Cecal intubation time
Time Frame: During the colonoscopy procedure.
Time from insertion to successful cecal intubation, measured in minutes.
During the colonoscopy procedure.
Withdrawal time
Time Frame: During the colonoscopy procedure.
Time from cecal intubation to scope withdrawal, measured in minutes.
During the colonoscopy procedure.
Volume of water infused
Time Frame: During the procedure.
Total volume of water infused during colonoscopy, measured in milliliters.
During the procedure.
Volume of fluid aspirated
Time Frame: During the procedure
Total volume of fluid aspirated during colonoscopy, measured in milliliters.
During the procedure
Patient-reported pain score
Time Frame: Immediately after the procedure.
Pain assessed using a visual analog scale (VAS) ranging from 0 (no pain) to 10 (worst pain imaginable).
Immediately after the procedure.
Patient satisfaction score
Time Frame: Immediately after the procedure.
Patient satisfaction assessed using a numeric rating scale from 0 to 10, where higher scores indicate greater satisfaction.
Immediately after the procedure.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Dalin Tzu Chi General Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

August 1, 2026

Primary Completion (Estimated)

May 1, 2028

Study Completion (Estimated)

September 1, 2028

Study Registration Dates

First Submitted

March 3, 2026

First Submitted That Met QC Criteria

June 23, 2026

First Posted (Actual)

June 29, 2026

Study Record Updates

Last Update Posted (Actual)

June 29, 2026

Last Update Submitted That Met QC Criteria

June 23, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • A11403003

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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