What is the recommended bowel prep protocol the day before a colonoscopy?

Recommended Bowel Preparation Protocol for Colonoscopy

The recommended bowel preparation protocol for colonoscopy is a split-dose regimen with a low-residue diet for breakfast and lunch the day before the procedure, followed by clear liquids until 2 hours before the colonoscopy. 1, 2

Diet Recommendations

• Day Before Colonoscopy:

  • Low-residue/low-fiber breakfast and lunch (not full regular meals)
  • Clear liquids only after lunch/midday meal
  • No solid food after lunch
  • No red or purple liquids (can interfere with visualization)
  • No alcohol consumption

• Clear Liquid Options:

  • Water, clear broths, coffee/tea (without milk/cream)
  • Clear juices without pulp (apple, white grape)
  • Sports drinks (not red/purple)
  • Gelatin (not red/purple)

Medication Protocol

Split-Dose Regimen (Preferred Method)

First Dose (Evening Before Procedure):

• Take first dose of bowel preparation (5:00-9:00 PM)
• Follow with at least five 8-ounce cups of clear liquids (40 oz total) within 5 hours

Second Dose (Morning of Procedure):

• Take second dose approximately 5 hours before colonoscopy
• Follow with at least three 8-ounce cups of clear liquids (24 oz total)
• Stop all fluid intake at least 2 hours before the procedure

Preparation Options

1. Low-Volume (2L) Preparations (Recommended):

   • 2L polyethylene glycol (PEG) preparations are preferred over 4L preparations due to similar efficacy with better tolerability 2
   • Prepare according to package instructions immediately before use

2. Sodium Picosulfate Preparation:

   • Mix packet with 5 ounces of cold water
   • Stir for 2-3 minutes until dissolved
   • Drink immediately after preparation 3

Special Considerations

• Avoid hyperosmotic regimens in patients at risk for volume overload or electrolyte disturbances 1
• Medication timing: Take oral medications at least 1 hour before or after starting bowel preparation 3
• For specific medications: Take tetracycline, fluoroquinolone antibiotics, iron, digoxin, chlorpromazine, or penicillamine at least 2 hours before and not less than 6 hours after bowel preparation 3
• Simethicone can be used as an adjunct to reduce bubbles during the procedure 1

Common Pitfalls to Avoid

1. Inadequate fluid intake: Insufficient clear liquid consumption after preparation doses leads to poor bowel cleansing
2. Timing errors: Taking the second dose too early or too late reduces effectiveness
3. Dietary non-compliance: Consuming high-fiber foods or solid foods after the cutoff time
4. Preparation dilution: Using incorrect amounts of water when mixing preparations

For Patients with Previous Inadequate Preparation

For patients with prior inadequate preparation, consider:

• Extended preparation period (start dietary restrictions earlier)
• Additional laxative doses
• More aggressive bowel regimen with modifications 1

Quality Assessment

Bowel preparation quality should be assessed only after washing and suctioning are completed. An adequate preparation allows for standard screening or surveillance intervals to be assigned based on colonoscopy findings 1.

The target rate for adequate bowel preparation should be at least 90% at both the individual endoscopist and endoscopy unit levels 1.