What is the preparation for a colonoscopy?

From the Guidelines

Colonoscopy preparation should involve a split-dose bowel cleansing regimen, with the second dose ideally starting 4-6 hours before the procedure and completion of the last dose at least 2 hours before the procedure time, as recommended by the US Multi-Society Task Force on Colorectal Cancer 1. To prepare for a colonoscopy, patients typically follow a clear liquid diet the day before the procedure and take a bowel-cleansing solution. The most commonly used regimen is a split-dose of polyethylene glycol (PEG) solutions like GoLYTELY, MoviPrep, or SUPREP.

• Take half the solution the evening before (around 6 PM)
• Take the remaining half about 4-5 hours before the colonoscopy Alternatively, non-PEG options include magnesium citrate or sodium phosphate products. During preparation, patients should drink only clear liquids like:
• Water
• Clear broth
• Coffee or tea without milk
• Clear juices
• Sports drinks
• Gelatin (avoiding red, purple, or blue colors) It is essential to stop all liquids 2-3 hours before the procedure. Some medications may need to be temporarily discontinued, particularly:
• Blood thinners
• Iron supplements
• Certain diabetes medications Thorough bowel cleansing is essential for the gastroenterologist to clearly visualize the colon lining and detect polyps or abnormalities, as supported by the US Multi-Society Task Force on Colorectal Cancer recommendations 1. Poor preparation can result in missed lesions or the need to reschedule the procedure, so following the preparation instructions precisely is crucial for an effective examination.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Preparation and Administration • Each packet of sodium picosulfate, magnesium oxide and anhydrous citric acid must be dissolved with water prior to ingestion and administered according to the dosing regimen. • Two doses (one packet per dose) of sodium picosulfate, magnesium oxide and anhydrous citric acid for oral solution are required for a complete preparation for colonoscopy. The preferred method is the “Split-Dose” method. The alternative is the “Day Before” method. Split-Dose Dosage Regimen (Preferred Method) • First dose: administer during evening before the colonoscopy • Second dose: administer the next day, during the morning prior to the colonoscopy. Day-Before Dosage Regimen (Alternative Method), if Split-Dosing is inappropriate • First dose: administer during afternoon or early evening before the colonoscopy. • Second dose: administer 6 hours later during evening before colonoscopy.

The preparation for a colonoscopy using sodium picosulfate, magnesium oxide and anhydrous citric acid for oral solution involves two doses, with the option of either the Split-Dose or Day-Before method.

• The Split-Dose method is the preferred method, where the first dose is taken in the evening before the colonoscopy, and the second dose is taken the next morning.
• The Day-Before method is an alternative, where the first dose is taken in the afternoon or early evening, and the second dose is taken 6 hours later. Additional fluids must be consumed after every dose, and oral medications should be taken at least 1 hour before or 6 hours after administration of the solution 2.

From the Research

Preparation Methods

• Sodium picosulphate with magnesium citrate (SPS-Mg) and polyethylene glycol electrolyte lavage (PEG-EL) solution are two common bowel preparation agents used for colonoscopy 3, 4.
• A split-dose regimen of SPS-Mg or PEG-EL can be effective for bowel preparation, with SPS-Mg being better tolerated by patients 4, 5.
• Polyethylene glycol (PEG) solution is also commonly used for bowel preparation, and its effectiveness can be similar to that of SPS-Mg 3, 4, 5.

Dietary Recommendations

• A clear liquid diet (CLD) is not mandatory for polyethylene glycol-based bowel preparation for afternoon colonoscopy in healthy outpatients, and a regular diet (RD) can be sufficient 6.
• A low-residue diet (LRD) before colonoscopy may improve tolerability by patients, with no differences in preparation quality 7.
• Dietary education concerning the avoidance of high-fiber foods for 3 days before colonoscopy is sufficient, at least for healthy outpatients 6.

Patient Tolerability and Compliance

• SPS-Mg is associated with significantly fewer side effects, such as nausea and vomiting, compared to PEG-EL 3, 4.
• Patients using SPS-Mg score better on aspects of convenience and flavor of the preparation agent compared to patients using PEG-EL 4.
• Split-dose SPMC is associated with increased patient tolerability and compliance compared to PEG solution 5.