What is the appropriate management for a 2.5‑month‑old infant who has not passed stool for seven days?

Management of a 2.5-Month-Old Infant with No Stool for 7 Days

Immediate Assessment

This infant requires urgent evaluation to rule out Hirschsprung disease or other serious causes of intestinal obstruction, as 7 days without stool at this age is highly abnormal and potentially life-threatening. 1

Critical Red Flags to Assess Immediately

• Bilious (green) vomiting – indicates obstruction distal to the ampulla of Vater and requires emergency surgical evaluation 2
• Abdominal distension – suggests intestinal obstruction 2
• Failure to pass meconium in the first 24-48 hours of life (obtain birth history) – classic for Hirschsprung disease 1
• Poor feeding or refusal to feed 2
• Lethargy or altered mental status 3
• Signs of dehydration: sunken fontanelle, dry mucous membranes, decreased skin turgor, prolonged capillary refill >3 seconds 1, 3

Physical Examination Priorities

• Abdominal examination: assess for distension, palpable stool masses, tenderness, or signs of peritonitis 2
• Digital rectal examination: essential to assess for anal patency, rectal tone, presence of stool in rectal vault, and to rule out anatomic abnormalities 4
• Hydration status: evaluate anterior fontanelle, mucous membranes, skin turgor, capillary refill, and vital signs 1, 3

Differential Diagnosis by Priority

Life-Threatening Causes (Require Emergency Intervention)

1. Hirschsprung disease – absence of ganglion cells causing functional obstruction; typically presents with delayed passage of meconium and progressive constipation 1
2. Intestinal obstruction (malrotation, volvulus, atresia) – presents with bilious vomiting, abdominal distension, and absence of stool 2
3. Severe dehydration – can occur secondary to poor intake or vomiting 1, 3

Other Important Causes

1. Hypothyroidism – can present with constipation in infancy 4
2. Cow's milk protein allergy – may cause constipation in formula-fed infants 5
3. Functional constipation – less likely at 2.5 months but possible, especially if recently transitioned from breast milk to formula 5

Immediate Management Algorithm

Step 1: Stabilize if Needed

• If signs of shock or severe dehydration present: administer 20 mL/kg IV bolus of normal saline or lactated Ringer's, repeat as needed until perfusion normalizes 1
• If bilious vomiting or signs of obstruction: make infant NPO (nothing by mouth), place nasogastric tube for decompression, obtain urgent surgical consultation 2

Step 2: Diagnostic Workup

Immediate studies if obstruction suspected:

• Abdominal X-ray (supine and upright or cross-table lateral) to assess for bowel gas pattern, distension, air-fluid levels 2
• Abdominal ultrasound if malrotation suspected 2

If Hirschsprung disease suspected (no meconium passage in first 48 hours of life, progressive symptoms):

• Rectal suction biopsy is the gold standard diagnostic test 5
• Contrast enema may show transition zone but does not rule out Hirschsprung disease 5

Metabolic screening:

• Thyroid function tests (TSH, free T4) to rule out hypothyroidism 4
• Electrolytes if dehydration present 3

Step 3: Initial Therapeutic Intervention

If no signs of obstruction and infant is stable:

• Glycerin suppository (infant size) is the safest first-line intervention for immediate relief in a 2.5-month-old 6
• Digital rectal stimulation with lubricated thermometer or finger may stimulate defecation 4

If suppository ineffective after 30-60 minutes:

• Lactulose: Initial dose for infants is 2.5-10 mL daily in divided doses; adjust to produce 2-3 soft stools daily 6
• Polyethylene glycol (PEG) is recommended as first-line pharmacologic therapy, though dosing in infants <6 months requires careful titration (typically 0.5-1 g/kg/day) 7

Step 4: Feeding Management

• Continue breastfeeding on demand without interruption 3
• For formula-fed infants: ensure adequate fluid intake and proper formula preparation; consider trial of different formula only if cow's milk protein allergy suspected 3, 5
• Do NOT dilute formula – this provides no benefit and worsens nutritional outcomes 1

Follow-Up and Monitoring

Immediate Return Precautions

Instruct caregivers to return immediately if:

• Bilious (green) vomiting develops 2
• Abdominal distension worsens 2
• Infant becomes lethargic or difficult to arouse 3
• No stool passage within 24 hours of intervention 6
• Signs of dehydration develop: decreased urine output (<4 wet diapers/24 hours), sunken fontanelle 3

Short-Term Follow-Up (24-48 Hours)

• Reassess stool pattern and frequency 6
• Monitor weight gain – poor weight gain suggests underlying pathology rather than simple constipation 2
• Adjust laxative dosing if needed to achieve 2-3 soft stools daily 6

Common Pitfalls to Avoid

• Do NOT assume this is simple functional constipation without ruling out Hirschsprung disease and other serious causes – 7 days without stool at 2.5 months is abnormal 1, 5
• Do NOT use stimulant laxatives (senna, bisacodyl) as first-line in infants – these are reserved for older children and should only be used under specialist guidance 7
• Do NOT use mineral oil in infants due to aspiration risk 7
• Do NOT delay surgical consultation if any signs of obstruction are present 2
• Do NOT rely solely on dietary changes (increased water, prune juice) as initial management when infant has not stooled for 7 days – pharmacologic intervention is needed 7

When to Refer to Pediatric Gastroenterology or Surgery

• Immediate surgical referral: bilious vomiting, signs of obstruction, peritonitis 2
• Urgent GI referral: suspected Hirschsprung disease, failure to respond to initial laxative therapy within 48 hours, recurrent severe constipation 5
• Routine GI referral: chronic constipation requiring ongoing management, need for specialized testing (anorectal manometry) 5, 4