What are the 5 most common causes of neonatal constipation?

The 5 Most Common Causes of Neonatal Constipation

The five most common causes of neonatal constipation are intestinal dysmotility, Hirschsprung disease, anal stenosis/atresia, intestinal malrotation, and functional megacolon. 1

1. Intestinal Dysmotility

Intestinal dysmotility is the most common cause of constipation in neonates. It is characterized by:

• Abnormal intestinal muscle contractions
• Often related to immaturity of the gastrointestinal tract
• May be exacerbated by feeding difficulties common in neonates
• Can be associated with other conditions like gastroesophageal reflux

Intestinal dysmotility-related constipation is often seen in children with certain syndromes, such as cardio-facio-cutaneous syndrome, where it can remain a lifelong problem 1.

2. Hirschsprung Disease (Congenital Aganglionic Megacolon)

Hirschsprung disease is a serious cause of neonatal constipation characterized by:

• Absence of ganglion cells in the submucosal and myenteric plexuses
• Typically presents with failure to pass meconium within 48 hours of birth
• Rectal examination reveals an empty, tight rectum (unlike functional constipation)
• May present with abdominal distention and bilious vomiting
• Without treatment, mortality approaches 50% by one year of age 2

Diagnosis is confirmed by rectal biopsy, and treatment is surgical 2, 3.

3. Anal Stenosis or Atresia

Anal abnormalities are important structural causes of neonatal constipation:

• May be apparent on physical examination
• Can range from complete atresia to stenosis
• Often associated with other congenital anomalies
• Requires surgical correction

Gastroenterologists can differentiate constipation caused by anal stenosis from other conditions 1.

4. Intestinal Malrotation

Malrotation can cause constipation in neonates due to:

• Abnormal positioning of intestines during development
• Potential for volvulus (twisting of the intestine)
• May present with bilious vomiting and abdominal distention
• Can be diagnosed with upper GI series 1

5. Functional Megacolon

Functional megacolon differs from Hirschsprung disease:

• Dilated colon with normal ganglion cells
• May be related to dietary factors or dehydration
• Often improves with age and proper management
• Less severe than Hirschsprung disease but can cause significant constipation

Important Clinical Considerations

When evaluating neonatal constipation, consider:

• Timing of onset: Constipation present from birth or beginning in the neonatal period is most likely to be congenital in origin 4
• Associated symptoms: Failure to thrive and gross abdominal distention suggest Hirschsprung disease 4
• Physical examination: Rectal examination typically reveals a distended rectum full of stool in functional constipation, while in Hirschsprung disease, the rectum is usually empty and tight 4

Less Common Causes to Consider

Other potential causes of neonatal constipation include:

• Hypothyroidism
• Cystic fibrosis
• Metabolic disorders
• Multiple intestinal atresias (rare but reported in combination with Hirschsprung disease) 5
• Disorders associated with specific genetic syndromes like 22q11.2 deletion syndrome 1

Early diagnosis and appropriate management of neonatal constipation are essential to prevent complications and improve outcomes. Referral to a pediatric gastroenterologist is recommended for persistent constipation or when organic causes are suspected.