What is the best colonoscopy preparation (prep)?

Best Colonoscopy Preparation Regimen

Low-volume (2L) polyethylene glycol (PEG) preparations administered in a split-dose regimen are the best colonoscopy preparation due to similar efficacy to high-volume preparations but with significantly better tolerability and patient compliance. 1, 2

Optimal Bowel Preparation Characteristics

Volume Considerations

• Low-volume (2L) PEG preparations are preferred over high-volume (4L) preparations because:
  • Similar efficacy for bowel cleansing (86.1% vs 87.4% adequate preparation rates)
  • Significantly better tolerability (72.5% vs 49.6%)
  • Higher patient willingness to repeat (89.5% vs 61.9%) 1, 2
  • Fewer symptoms of nausea and pain 1

Split-Dose Administration

• Split-dose regimen is strongly recommended regardless of preparation volume 2
  • First half taken the evening before the procedure
  • Second half taken 4-6 hours before colonoscopy (completed at least 2 hours before the procedure)
  • Significantly increases the number of satisfactory bowel preparations (OR 3.70; 95% CI, 2.79-4.91) 3
  • Decreases preparation discontinuations (OR 0.53; 95% CI, 0.28-0.98) 3
  • Reduces nausea (OR 0.55; 95% CI, 0.38-0.79) 3
  • Improves polyp detection rates (23.3% vs 10.8% in single-dose) 4

FDA-Approved Low-Volume Options

• 2L PEG + ascorbate
• 2L PEG-3350 + sodium sulfate, potassium chloride, magnesium sulfate, and sodium chloride
• 1L PEG + ascorbate 1

Special Considerations

Medical History Factors

• Patient's medical history should guide preparation selection 1
  • Patients with renal insufficiency, heart failure, or advanced liver disease should use 4L PEG-ELS preparations 2
  • Hyperosmotic regimens are contraindicated in individuals at risk for volume overload or electrolyte disturbances 1
  • Phosphate-based preparations are contraindicated in patients with:
    • Impaired renal function
    • Heart failure
    • Pre-existing electrolyte disturbances
    • Cirrhosis or ascites
    • Advanced age with comorbidities 2

High-Risk Patients

• Patients at higher risk for inadequate preparation include those with:
  • Prior inadequate preparation
  • History of constipation
  • Use of opioids or other constipating medications
  • Prior colon resection
  • Diabetes mellitus
  • Spinal cord injury 2

Promising Emerging Options

Ultra-Low-Volume Preparations

• 1L PEG + linaclotide (290 mcg) has shown promising results:

  • Non-inferior to 2L PEG regimen for bowel preparation quality (90.5% vs 91.6% adequate preparation)
  • Higher patient willingness to repeat (95.2% vs 82.2%)
  • Fewer reports of nausea and vomiting 1, 5

• Split-dose oral sulfate solution (<1L):

  • 92% rate of adequate bowel preparation 1
  • Non-inferior to split-dose 4L PEG (98.0% vs 96% adequate preparation)
  • Higher acceptance, compliance, and satisfaction 6
  • Note: More frequent abdominal pain compared to PEG (7.1% vs 1.0%) 6

Dietary Recommendations

• Low-residue/low-fiber diet for breakfast and lunch the day before colonoscopy
• Clear fluids allowed up to 2 hours before the procedure
• Traditional overnight fasting from midnight is unnecessary for most patients 2

Common Pitfalls and How to Avoid Them

1. Inadequate patient education

   • Provide clear written and verbal instructions
   • Consider patient navigation services to improve preparation rates 2

2. Not accounting for medical comorbidities

   • Always review patient's medical history before selecting preparation regimen
   • Monitor electrolytes before and after procedure in high-risk patients 2

3. Ignoring the importance of timing

   • Emphasize the critical importance of following the split-dose timing instructions
   • Complete the second dose at least 2 hours before the procedure 2

4. Insufficient hydration

   • Encourage adequate fluid intake during preparation
   • Monitor for signs of dehydration 2