How to manage functional constipation in a 3-year-old with a 6-month history of stool withholding and infrequent bowel movements (BMs)?

Management of Functional Constipation in a 3-Year-Old with Stool Withholding

Start with polyethylene glycol (PEG) as first-line treatment after initial disimpaction, as it is the most effective medication for functional constipation in children and has superior efficacy compared to all other interventions. 1

Initial Assessment and Disimpaction Phase

Before starting maintenance therapy, assess for fecal impaction through history and physical examination, looking specifically for:

• Abdominal distension or palpable stool masses 2
• Evidence of overflow incontinence (soiling) 3
• Rectal examination is now performed less often as it can be distressing and may be deceptive 2

If fecal impaction is present (likely given 7-day intervals without BM), begin with disimpaction using high-dose PEG for the first few days. 3 The disimpaction phase typically requires higher doses than maintenance therapy and should continue until the child passes soft stools without straining 4, 3.

Maintenance Treatment Protocol

After disimpaction, initiate PEG 17g mixed in 8 ounces of water once daily as maintenance therapy. 5, 1 This is FDA-approved and generally produces a bowel movement within 1-3 days 6. The goal is to achieve 2-3 soft stools daily 7.

Dosing for a 3-Year-Old:

• Start with age-appropriate dosing: for children this age, typical doses range within the 40-90 mL daily range for older children, adjusted based on response 7
• Adjust the dose every 1-2 days to produce soft, comfortable stools 4
• If diarrhea occurs, reduce the dose immediately 7

If PEG Alone is Insufficient:

Add a stimulant laxative such as bisacodyl for rescue therapy, with the goal of one non-forced bowel movement every 1-2 days. 5 However, stimulant laxatives should not be used continuously for more than one week without medical supervision 5.

Critical Non-Pharmacological Interventions

Education and behavioral modification are instrumental in improving functional constipation and must be implemented alongside medication. 8

Parent and Child Education:

• Explain the pathophysiology of constipation and the cycle of stool withholding 1, 4
• Emphasize that treatment may be required for months to years, as relapse is common (only 50-70% show long-term improvement) 8
• Address parental concerns about long-term laxative use, which is a major contributor to treatment failure 9

Toilet Training with Reward System:

• Implement scheduled toilet sitting after meals (taking advantage of the gastrocolic reflex) 4
• Use positive reinforcement and reward systems for sitting attempts, not just successful bowel movements 4
• Ensure proper toilet positioning with feet supported to facilitate defecation 3

Dietary Modifications:

• Consider a trial of cow's milk exclusion if constipation persists, as milk may promote constipation in some children. 8, 10
• Ensure adequate fluid intake, particularly if the child has low fluid consumption 5
• Increase dietary fiber only if the child has adequate fluid intake, as fiber without sufficient hydration can worsen constipation 5

Defecation Diary:

Use a bowel diary and Bristol Stool Scale to monitor treatment response objectively. 2 This helps track frequency, consistency, and any episodes of withholding behavior.

Duration and Weaning

Maintenance treatment typically requires months to years because relapse of functional constipation is common. 8 Continue PEG at the effective maintenance dose until the child has regular, comfortable bowel movements for an extended period (typically 3-6 months minimum) before attempting to wean 4.

Common Pitfalls to Avoid

• Do not use stool softeners like docusate as they are less effective than osmotic laxatives like PEG and provide no additional benefit. 1
• Avoid magnesium-based laxatives in patients with any renal concerns due to risk of hypermagnesemia. 5
• Do not rely on increased water intake, probiotics, or synbiotics alone, as studies show no benefit for these interventions. 10
• Avoid premature discontinuation of treatment—this is the most common cause of relapse. 4, 8
• Do not add biofeedback therapy, as it does not improve outcomes in functional constipation. 10

When to Escalate

If the child fails to respond to PEG plus behavioral interventions after adequate trial (4-8 weeks at appropriate doses), consider:

• Reassessing for organic causes (though rare in functional constipation) 8
• Evaluating psychological factors that may require specific intervention 2
• Referral to pediatric gastroenterology for refractory cases 4