What is the appropriate next step in managing an 11-year-old boy with chronic constipation who presents with abdominal pain and a 4‑day delay in bowel movement, without nausea or vomiting?

Management of an 11-Year-Old with Chronic Constipation and Acute Abdominal Pain

Start with polyethylene glycol (PEG) 3350 at 0.8-1 g/kg/day (approximately 17 grams for an average 11-year-old) after ruling out fecal impaction via digital rectal examination. 1

Immediate Assessment Required

Before initiating any treatment, perform a digital rectal examination to assess for fecal impaction, which is critical in a child with 4 days since last bowel movement and abdominal pain. 1, 2

• If impaction is present: Use glycerin suppositories or manual disimpaction as first-line therapy before starting maintenance laxatives. 1
• If no impaction: Proceed directly to oral laxative therapy. 1

The absence of nausea and vomiting makes bowel obstruction less likely, but you must still rule out this possibility through physical examination (checking for distension, high-pitched bowel sounds, or peritoneal signs). 3, 1

First-Line Pharmacological Treatment

Polyethylene glycol (PEG) 3350 is the laxative of first choice for children 6 months and older with functional constipation. 1

• Dosing: Start at 0.8-1 g/kg/day (typically 17 grams for an 11-year-old), mixed in 4-8 ounces of water, juice, or other beverage. 1, 4
• Goal: Achieve 2-3 soft, painless stools daily, not necessarily daily bowel movements. 1
• Timeline: May take 2-4 days to produce a bowel movement. 4
• Mechanism: PEG works as an osmotic laxative by sequestering fluid in the intestinal lumen, increasing stool water content. 1

Alternative First-Line Options

If PEG is unavailable or not tolerated, consider:

• Milk of magnesia (magnesium hydroxide): Inexpensive osmotic alternative with comparable efficacy. 3
• Lactulose or sorbitol-containing juices (prune, pear, apple): Particularly useful in younger children. 1

Avoid bisacodyl or other stimulant laxatives as first-line therapy in pediatric constipation—these should be reserved for rescue therapy or when osmotic agents fail. 3, 1

Critical Red Flags to Assess

While functional constipation is most common in children, you must screen for organic causes: 1, 2

• Delayed passage of first stool beyond 48 hours after birth (suggests Hirschsprung disease—ask about neonatal history). 1
• Cutaneous markers on lower back (dimples, hair tufts, hemangiomas suggesting spinal dysraphism). 1
• Neurological symptoms: Progressive gait abnormalities, lower limb weakness, bladder dysfunction, or urinary incontinence. 5, 1
• Metabolic screening: Consider checking for hypothyroidism, hypercalcemia, hypokalemia, or diabetes mellitus if clinical suspicion exists. 3, 1

Maintenance and Follow-Up Strategy

Maintenance therapy must continue for many months (often 6-12 months or longer) before the child regains normal bowel motility and rectal perception. 1, 2

• Monitor for: Stool frequency and consistency, absence of pain with defecation, and normal growth parameters. 1
• Warning signs requiring immediate evaluation: Rectal bleeding, severe cramping, bloating, or diarrhea. 1, 4
• Relapse is common: 40-50% of children experience relapse within 5 years if maintenance therapy is discontinued prematurely. 1

Non-Pharmacological Adjuncts

While starting PEG, implement these supportive measures: 1

• Increase fluid intake to maintain proper hydration (essential with fiber or osmotic laxatives). 1
• Dietary fiber: Increase through age-appropriate foods (fruits, vegetables, whole grains, legumes), but fiber supplements alone are ineffective for medication-induced or severe constipation. 3, 1
• Regular toileting schedule: Establish consistent times for attempted bowel movements, particularly after meals. 1
• Physical activity: Encourage age-appropriate regular exercise. 1

Common Pitfalls to Avoid

• Do not add stool softeners (docusate) to PEG—evidence shows no additional benefit. 3, 1
• Do not rely on fiber supplements alone without adequate hydration (at least 2 liters daily) or for established constipation. 3
• Do not discontinue treatment prematurely—parents often stop therapy before the child regains normal bowel function, leading to relapse. 1
• Do not use suppositories or enemas if the child has neutropenia, thrombocytopenia, recent colorectal surgery, or severe colitis. 1

When to Escalate Treatment

If constipation persists after 1-2 weeks of PEG at adequate dosing: 3, 1

• Add a second agent: Consider lactulose, magnesium hydroxide, or rectal bisacodyl as rescue therapy. 3
• Reassess for impaction or obstruction if symptoms worsen or fail to improve. 3
• Consider referral to pediatric gastroenterology if refractory to standard therapy or if organic causes are suspected. 6