GENERAL CONSIDERATIONS

It is important that patients are educated and engaged in the colonoscopy preparation process, and it has been shown that effective education significantly improves the quality of bowel preparation. Patient counseling along with written instructions that are simple and easy to follow and in their native language should be provided to patients, and patient education may improve with the use of visual aids. Recently, educational booklets were shown to improve bowel preparation and quality indicators such as cecal intubation rates. Smartphone applications have even been developed to guide patients through the preparation process.

Bowel preparation regimens typically incorporate dietary modifications along with oral cathartics.Most commonly, a clear liquid diet is advised for the day before colonoscopy. Red liquids can be mistaken for blood in the colon or can obscure mucosal details and should be avoided. Clear liquids can be taken up to 2 hours before the procedure. However, it is not clear whether a clear liquid diet the day before colonoscopy offers advantages over a low-fiber diet in terms of preparation quality. A low-residue diet that avoids foods containing seeds and other indigestible substances is often recommended for several days before the procedure and has been shown to be at least as effective as a clear liquid diet and associated with increased patient satisfaction.

Although the individual components of bowel preparations vary widely, the combination of dietary restriction and cathartics has proven to be safe and effective for colonic cleansing for colonoscopy. In a study of hospitalized patients undergoing colonoscopy, a clear liquid diet before administration of the bowel preparation was the only dietary modification that improved the quality of preparation. Adequate hydration is an important adjunct to any bowel preparation before colonoscopy. Additional medication modifications may be required in special populations such as diabetic patients, who must maintain glycemic control, and patients taking anticoagulation agents.

TIMING OF PREPARATION

Giving part (usually half) of the bowel preparation dose on the same day as the colonoscopy (termed splitdose) results in a higher-quality colonoscopy examination compared with ingestion of the entire preparation on the day or evening before colonoscopy. A higher-quality bowel preparation due to this split-dose has been demonstrated to increase the adenoma detection rate. In addition to a higher-quality bowel preparation, split-dosing also improves patient tolerance, as demonstrated by an increased willingness to repeat the procedure using the same preparation in the future. Typically, the standard dose of a bowel preparation is split between the day before and the morning of the procedure. The timing of the second dose must allow sufficient time for the patient to complete the second dose, have the desired response, and for the patient to travel to the center where the colonoscopy will be performed. The second dose should be administered between 3 to 8 hours before the planned start of the colonoscopy procedure. A prospective trial found no difference in residual gastric fluid in patients using split-dose bowel preparation and bowel preparation given the evening before colonoscopy. Patients must have completed the preparation at least 2 hours before sedation is given to avoid potential aspiration as recommended in the American Society of Anesthesiologists (ASA) guidelines.xHowever, institutional policies may vary from this ASA recommendation. In patients with early morning appointments, this second morning dose may be inconvenient as it may require waking very early to take the second dose of bowel preparation. However, when educated on the advantages of split-dose bowel preparation on effectiveness of cleansing, the vast majority of potential patients express willingness to awaken at 2 to 3 AM to complete the regimen. This approach has repeatedly been shown to result in an improved quality of colonic cleansing and is recommended for both morning and afternoon procedures. Hospitalized patients also prefer splitdosing, although no difference in quality of preparation was noted compared with a morning-only preparation In patients undergoing colonoscopy in the afternoon, the bowel preparation may be administered entirely on the morning of the examination. One study of a 4-L bowel preparation in patients undergoing afternoon procedures demonstrated superior quality and tolerability when ingested the morning of the procedure compared with the evening before.Other studies have also shown equivalent or improved bowel preparation quality with superior tolerability, less impact on activities of daily living, and better sleep quality when the bowel preparation is given only on the day of the procedure for afternoon colonoscopies