What is the proper way to perform bowel preparation using Miralax (polyethylene glycol) and Fleet's enema?

Proper Bowel Preparation Using Miralax and Fleet's Enema

The proper bowel preparation using Miralax (polyethylene glycol 3350) involves mixing 238-255g (typically one 8.3oz bottle) with 64 ounces of clear liquid, preferably split into two doses, while Fleet's enema should be administered 1-2 hours before the procedure as a supplementary measure only when necessary. 1, 2

Miralax Preparation Protocol

Standard Miralax Protocol

1. Timing and Dosing:

   • Mix one 8.3oz bottle of Miralax (238-255g) with 64 ounces of clear liquid (preferably split into two doses)
   • First dose: Evening before procedure (typically 4-6 PM)
   • Second dose: Morning of procedure (4-5 hours before appointment)
   • Complete the second dose at least 3 hours before the procedure

2. Liquid Selection:

   • Use clear liquids such as water, clear sports drinks, or clear juices
   • Avoid red, purple, or blue colored liquids
   • Sugar-free options recommended for patients with diabetes

3. Dietary Restrictions:

   • Begin clear liquid diet the day before the procedure
   • No solid food starting 24 hours before the procedure
   • Continue clear liquids until 3 hours before the procedure

Important Considerations

• While widely used, it's important to note that Miralax-based bowel preparation is not FDA-approved for colonoscopy preparation 1
• Split dosing (taking preparation in two separate doses) significantly improves bowel cleansing quality 1, 3
• Miralax draws water into the intestinal lumen, increasing stool bulk and softness without net electrolyte changes 2

Fleet's Enema Protocol

When to Use Fleet's Enema

• Fleet's enema should be used as a supplementary measure, not as the primary bowel preparation 1
• Indications for use:
  • When oral preparation is inadequate
  • When patients report brown effluent despite compliance with oral preparation
  • As rescue therapy for inadequate preparation

Administration Technique

1. Timing:

   • Administer 1-2 hours before the procedure 4, 5
   • For rescue therapy: can be administered during the procedure if initial preparation is inadequate 1, 6

2. Proper Administration:

   • Patient should lie on left side with knees bent
   • Gently insert the lubricated tip into the rectum
   • Slowly squeeze the bottle until empty
   • Patient should hold the solution for 5-10 minutes if possible
   • Allow patient to evacuate contents in the bathroom

Combined Approach for Better Results

For patients at risk of inadequate preparation:

1. Start with standard Miralax protocol
2. Add Fleet's enema 1-2 hours before the procedure

For rescue of inadequate preparation during colonoscopy:

1. Consider colonoscopic enema technique (500ml polyethylene glycol solution instilled at the level of hepatic flexure) 6
2. Allow patient to recover from sedation and evacuate contents
3. Resume colonoscopy after evacuation

Efficacy and Limitations

• Miralax-based preparations have shown slightly inferior bowel preparation quality compared to 4L PEG solutions but better patient tolerance 7
• Fleet's enema alone is insufficient for complete bowel preparation but useful as a supplementary measure 4
• The combination of magnesium citrate with Fleet's enema has shown superior results (70% excellent preparation) compared to Fleet's enema alone 5

Cautions and Contraindications

• Avoid magnesium-based products in patients with renal impairment 2
• Fleet's phosphate enemas should be used with caution in elderly patients due to risk of electrolyte abnormalities 1
• Bowel preparation is contraindicated in patients with bowel obstruction, ileus, or hypersensitivity to ingredients 1

Monitoring for Adequacy

• Adequate preparation should result in clear or light yellow liquid stool
• If brown liquid or solid effluent persists after preparation, there is a 54% chance of inadequate preparation 1
• In such cases, consider additional Fleet's enema or extending the preparation time