What is the recommended dosing regimen for Polyethylene Glycol (PEG) 3350 for the treatment of fecal stasis?

How to Give PEG for Fecal Stasis

For fecal stasis (fecal impaction), start with PEG 3350 at higher doses than standard constipation treatment: use 68 grams as a single dose mixed in 500 mL of liquid for rapid disimpaction within 24 hours, or use the escalating regimen of 2-8 sachets (approximately 29-118 grams) daily for 2 days, then reduce to 2-6 sachets on day 3. 1, 2

Initial Assessment Before Treatment

Before initiating PEG therapy for fecal stasis, you must:

• Rule out bowel obstruction or paralytic ileus, as these are absolute contraindications to laxative therapy 3
• Assess for complete fecal impaction that may require manual disimpaction or enema before oral PEG can be effective 3
• Evaluate bleeding risk in patients on anticoagulation, as rectal interventions may be needed if PEG alone fails 3

Dosing Regimen for Fecal Stasis

High-Dose Rapid Disimpaction Protocol

For acute fecal stasis requiring rapid relief within 24 hours:

• Administer 68 grams of PEG 3350 as a single dose mixed in 500 mL of flavored water 1
• This dose produces a median of 2.2 bowel movements within 24 hours, with the first bowel movement occurring at approximately 14.8 hours 1
• 50% of patients achieve complete evacuation with the first bowel movement, and 100% by the second bowel movement 1
• This high-dose regimen is safe with no adverse electrolyte changes, incontinence, severe cramping, or diarrhea reported 1

Multi-Day Disimpaction Protocol

For severe fecal impaction with palpable fecaloma:

• Days 1-2: Give 2-8 sachets of PEG 3350 with electrolytes (each sachet = 14.7g, total dose 29-118 grams daily) 2
• Day 3: Reduce to 2-6 sachets (29-88 grams) 2
• This regimen produces approximately 2.2 liters of soft stool over 7 days and resolves fecalomas in 40-50% of severe cases 2
• If fecaloma persists after 7 days, repeat the high-dose cycle for a longer duration 2

Critical Implementation Points

Mixing and Fluid Requirements

• Mix PEG powder in at least 4-8 ounces of liquid (water, juice, soda, coffee, or tea are all acceptable) 4
• Insufficient liquid volume is the most common cause of treatment failure 4
• Patients must maintain adequate daily fluid intake throughout the day, beyond just the mixing liquid, for PEG to work effectively 3, 4

Adding Rectal Therapy When PEG Fails

If no bowel movement occurs by day 3-4 despite adequate PEG dosing:

• Add bisacodyl suppository 10mg or glycerin suppository while continuing PEG 3350 3
• Do not delay rectal intervention beyond 3-4 days, as the risk of worsening impaction increases 3
• The combination uses different mechanisms: PEG works osmotically while suppositories provide direct rectal stimulation 3

Transition to Maintenance Therapy

Once disimpaction is achieved:

• Continue PEG 3350 at standard maintenance dose of 17 grams once daily mixed in 4-8 ounces of liquid 4
• The American Gastroenterological Association supports continuing PEG as maintenance therapy given its durable response over 6 months 4
• 61.7% of patients require additional laxative interventions within 30 days of stopping PEG, indicating most patients benefit from continued maintenance 5
• Consider adding an oral stimulant laxative (senna or bisacodyl) to PEG if recurrent fecal stasis occurs 3

Common Pitfalls to Avoid

• Do not assume PEG failure without confirming adequate dosing and fluid intake, as many patients do not mix with sufficient liquid 3
• Do not add fiber supplements when treating established fecal stasis, as fiber is ineffective and may worsen symptoms 3
• Do not use suppositories in patients on anticoagulation without assessing bleeding risk due to potential for rectal bleeding or intramural hematoma 3
• Do not use standard 17-gram daily dosing for acute fecal stasis, as this dose is designed for chronic constipation and takes 2-4 days to work 4, 1

Safety Profile

• Common side effects include abdominal distension, loose stools, flatulence, nausea, bloating, and cramping 4
• High doses (68-85 grams) do not cause electrolyte disturbances, changes in calcium, glucose, BUN, creatinine, or serum osmolality 1
• Daily PEG therapy is not associated with sustained elevation of ethylene glycol, diethylene glycol, or triethylene glycol blood levels, and peak values remain well below toxic levels 6