What is the best course of treatment for a 5-month-old infant with ileus and fecal retention?

Management of Ileus and Fecal Retention in a 5-Month-Old Infant

This clinical presentation requires urgent evaluation to exclude life-threatening causes such as Hirschsprung's disease, intestinal atresia, malrotation, or other congenital anomalies before initiating any treatment, as ileus in a 5-month-old is not typical functional constipation and demands immediate diagnostic workup. 1

Critical Initial Assessment

Red Flags Requiring Immediate Investigation

• Abdominal distension, bilious vomiting, fever, lethargy, or signs of peritonitis mandate emergent surgical consultation 2
• Ileus at 5 months of age is pathologic until proven otherwise—this is not simple constipation 1
• Plain abdominal radiographs are essential to determine the level and nature of obstruction 1
• Consider Hirschsprung's disease, meconium plug syndrome, intestinal atresia, malrotation, or pseudo-obstruction as potential etiologies 3

Hydration Status Assessment

• Evaluate skin turgor, mucous membranes, mental status, pulse, and capillary refill time 4
• Weigh the infant to establish baseline and monitor treatment effectiveness 4
• Categorize dehydration: mild (3-5% deficit), moderate (6-9% deficit), or severe (≥10% with shock) 4

Diagnostic Workup

Essential Investigations

• Plain abdominal radiographs to identify obstruction level, dilated bowel loops, air-fluid levels, or absence of rectal gas 1
• Consider contrast enema if Hirschsprung's disease or meconium plug syndrome suspected 1
• Surgical consultation is mandatory if mechanical obstruction cannot be excluded 1

Organic Causes to Exclude

• Hirschsprung's disease (congenital aganglionic megacolon) 3
• Intestinal atresia or stenosis 1
• Malrotation with or without volvulus 1
• Hypothyroidism, cystic fibrosis, or other metabolic disorders 3
• Spinal cord abnormalities 3

Management Algorithm

If Mechanical Obstruction is Present

• NPO (nothing by mouth) status immediately 2
• Nasogastric tube decompression 2
• Intravenous fluid resuscitation with isotonic crystalloids 2
• Urgent surgical intervention as indicated 2
• Broad-spectrum antibiotics if perforation or peritonitis suspected: consider ampicillin, gentamicin, and metronidazole for neonates 2

If Functional Ileus Without Mechanical Obstruction

Rehydration Protocol

• For mild-moderate dehydration: Administer 50-100 mL/kg oral rehydration solution (ORS) containing 50-90 mEq/L sodium over 2-4 hours 4
• For severe dehydration: Give 20 mL/kg boluses of Ringer's lactate or normal saline IV until perfusion normalizes 4
• Replace ongoing losses with 10 mL/kg ORS for each liquid stool and 2 mL/kg for each vomiting episode 4

Feeding Management

• Continue breastfeeding on demand if the infant is breastfed—do not interrupt nursing 4, 5
• For formula-fed infants, resume full-strength lactose-free or lactose-reduced formula immediately after rehydration 4
• Consider 2-4 week trial of maternal exclusion diet (eliminating milk and eggs) if breastfed, or extensively hydrolyzed protein formula if formula-fed, as milk protein allergy can mimic gastrointestinal obstruction 2

Addressing Fecal Retention (Only After Excluding Mechanical Obstruction)

• Fruit juices containing sorbitol (10 mL/kg body weight) as first-line dietary intervention 5
• Lactulose 2.5-10 mL daily in divided doses if dietary modifications insufficient 5
• Ensure adequate fluid intake to maintain stool consistency 5
• Glycerin suppositories may be considered for acute relief in infants, though evidence is limited 3

Critical Contraindications

• Absolutely avoid loperamide or any antidiarrheal agents in infants under 2 years due to risks of respiratory depression, cardiac arrest, and death 4
• Do not use stimulant laxatives like senna in infants this young without specialist guidance 6
• Avoid enemas in the setting of suspected mechanical obstruction 2

When to Return Immediately

Parents must bring the infant back if any of the following develop:

• Irritability, lethargy, or altered mental status 4
• Decreased urine output (sign of worsening dehydration) 4
• Intractable vomiting, especially if bilious 2, 4
• Worsening abdominal distension 2
• Fever or signs of sepsis 2
• Bloody stools 2

Common Pitfalls to Avoid

• Never assume functional constipation in a 5-month-old with ileus—organic pathology must be excluded first 1, 3
• Do not delay imaging or surgical consultation while attempting medical management 1
• Avoid diagnosing lactose intolerance based solely on stool pH or reducing substances without clinical correlation 4
• Do not dilute formula or delay full-strength feeding once rehydration is achieved, as this worsens nutritional outcomes 4
• Never use antidiarrheal medications in this age group 4

Follow-Up and Monitoring

• Close monitoring for 24-48 hours after initial presentation 4
• If functional constipation is confirmed, maintenance therapy may be required for months, as relapse is common 3
• Only 50-70% of children with functional constipation show long-term improvement despite treatment 3
• Behavioral education and family support are instrumental in managing chronic constipation 3