Comparing Bowel Preparation Regimens for Flexible Sigmoidoscopy

Background:

Flexible sigmoidoscopy is an accepted screening modality for colorectal cancer, however, it has put significant strain on endoscopy suite resources. It is important that flexible sigmoidoscopies be done completely and efficiently.

Cleansing before sigmoidoscopy is important to optimize the diagnostic yield of the exam and for polyp detection rates and other colonic lesions. Rectal enemas have been the mainstay of sigmoidoscopy preparations for many endoscopy suites. Procedure prolongation due to the requirement for additional enemas or more washing of a poorly cleansed colon can put a strain on endoscopy time to complete the procedures.

Oral preparations have been a mainstay of colonoscopy cleansing as they allow adequate visualization of the entire colon and are superior to rectal enemas in this regard. Large volume preparations dominate oral colon cleansing. Polyethylene glycol is a large volume solution with an osmotically balanced laxative. Large volume preps are poorly tolerated when compared with small volume preparations. Small volume osmotically active agents can have limitations also, but are being used more frequently with newer agents having a better safety profile.

Few large controlled studies have looked at oral preparation being given in sigmoidoscopy. Tolerability of oral prep has had a negative impact on patient compliance with these regimens in colonoscopy. However, rectal enemas also have had a negative impact on sigmoidoscopy experience.

Many sigmoidoscopies are incomplete or poorly done due to poor prep. Literature for oral bowel preparation regimens has been done predominantly for colonoscopies. The few studies comparing oral preparations to enemas are done without validated methods to record bowel preparation adequately and objectively (1, 2). The goal of our study is to compare the quality of the bowel preparation with oral preparations and rectal enemas to determine which is best.

The investigators plan on determining if the concentration of combustible gases with oral preparations during sigmoidoscopy would be reduced enough to allow for safe electrocautery use during sigmoidoscopy. Hydrogen and methane are two major combustible gases found in a normal colon. These gases can cause explosions in the bowel at the time on sigmoidoscopy if electrocautery is used. The explosive range of hydrogen in air is 4-74%, and for methane this range is 5-15% (3). Levels of combustible gases in the colon have been found to be unsafe in a bowel prepped with two phosphosoda enemas.(4) Several bowel cleansing regimens have been found to be safe for electrocautery by decreasing the concentrations of combustible gases in the colon. Our hypothesis is that a partial oral bowel preparation, will reduce the concentration of combustible gases in the colon to low enough levels to make electrocautery safe during flexible sigmoidoscopy.

Objective and Hypothesis:

Our objective is to help determine the efficacy of oral and rectal bowel preparation regimens for sigmoidoscopy. Our hypothesis is that oral preparation will reduce the amount of repeat rectal enemas required and improve the quality of a bowel exam at the sigmoidoscopy.

Inclusion criteria

• Consecutive male and non-pregnant female patients >18 years old who require outpatient sigmoidoscopy will be considered for inclusion.

Exclusion criteria

• previous colorectal surgery and patients with reduced renal function or other medical conditions that would increase the risk of receiving oral PicoSalx would be excluded from the study.