Overview
Definition
A congenital anomaly characterized by the absence of ganglion cells in the myenteric and submucosal plexuses of the distal bowel, leading to functional obstruction.
Epidemiology
Prevalence ~1 in 5,000 live births. More common in males. Associated with Down Syndrome (trisomy 21 in ~10% of cases).
Etiology & Risk Factors
- Failure of craniocaudal migration of neural crest cells during embryonic development, leaving a segment of distal colon aganglionic
Clinical Symptoms
- Failure of term newborn to pass meconium within the first 48 hours of life
- Abdominal distention and bilious vomiting
- Chronic constipation with foul-smelling, ribbon-like stools
- Explosive release of gas and stool upon digital rectal exam ('squirt sign' or 'blast sign')
Clinical Approach
Diagnosis
- Anorectal manometry showing failure of internal anal sphincter to relax
- Barium enema showing transition zone between narrow aganglionic distal colon and dilated proximal colon
- Rectal suction biopsy (gold standard) showing absence of ganglion cells and hypertrophied nerve fibers
Management
- Surgical resection of the aganglionic segment and pull-through of healthy, ganglionic bowel to the anus (usually staged with temporary colostomy)
Complications
- Hirschsprung-associated enterocolitis (HAEC, life-threatening toxic dilation/infection)
- Fecal incontinence or chronic constipation post-op