Flavoring

There have been many attempts to improve the flavor of PEG-ELS. As a result, PEG-ELS is available in multiple flavors. Gatorade, Crystal Light, and carbohydrateelectrolyte solutions have been used to improve palatability in nonelectrolyte balanced PEG solutions; however, improved flavor does not necessarily equate to improved tolerance. Care must be taken to avoid adding substrates to the preparation that can metabolize into explosive gases or significantly alter water and electrolyte absorbtion. One study suggested that sugar-free menthol candy drops may improve palatability and tolerability of a split-dose PEG-ELS preparation

Nasogastric tube administration of colonic preparations

 NG tubes have been used to instill colonic preparations, primarily PEG-ELS solutions, in both children and adults. The use of NG tubes to prepare a patient for colonoscopy may be required in patients unable to drink fluids or with a significant swallowing disorder. Purge preparations (rapid and high-volume) for patients with lower GI bleeding and urgent colonoscopy may require the placement and use of a NG tube. In addition to the potential adverse events related to placement of the NG tube, case reports have demonstrated the potential for severe, lifethreatening adverse events, such as aspiration.57 Adjunctive use of prokinetic and antiemetic agents as well as avoidance of overrapid installation of bowel preparation may make this route of administration more tolerable.

Metoclopramide 

Metoclopramide is a dopamine antagonist gastroprokinetic that increases the amplitude of gastric contraction and increases peristalsis of the duodenum and jejunum, but does not change colonic motility. In one study, metoclopramide (5-10 mg orally) used as an adjunct to PEG-ELS reduced nausea and bloating, but did not improve colonic cleansing.59 However, a second study revealed no advantage with either patient tolerance or colonic cleansing.60 Metoclopramide is not recommended as an adjunct to oral bowel preparation. 

Simethicone 

Simethicone promotes the clearance of excessive gas in the GI tract that reduces bloating, abdominal discomfort, and abdominal pain and improves visualization in the GI tract. There have been several studies investigating the addition of simethicone to bowel preparation regimens.122 Overall, simethicone does not significantly change the quality of the bowel preparation; however, it does reduce the number of adherent bubbles present, which may enhance colonic visualization.

DOCUMENTATION OF PREPARATION QUALITY

 It is important for preparation quality to be properly documented in colonoscopy reports. The U.S. MultiSociety Task Force on Colorectal Cancer defines an adequate examination as one that allows confidence that lesions other than small (%5 mm) polyps were generally not obscured by residual colonic contents. In clinical practice, preparation quality should be graded after efforts to remove residual effluent and fecal debris have been completed. Validated scoring systems that have been devised to rate the quality of colonoscopy preparation in clinical trials include the Aronchick Scale, the Ottawa Bowel Preparation Scale, and the Boston Bowel Prep Score  The Aronchik Scale is a global rating best suited for comparing different bowel preparations because it assesses the quality of the preparation encountered during the intial inspection of the colon. The Ottawa Bowel Preparation Scale uses 3 colonic segment scores that are rated 0 to 4 and summed as part of a total score. The score has been validated comparison with the Aronchik Scale. The Boston Bowel Preparation Score uses a 10-point score (0-9) summation score assessing bowel preparation quality in 3 segments of the colon after all cleansing maneuvers during colonoscopy and has been found to be both valid and reliable