Hirschsprung disease (congenital aganglionic megacolon) !
- Malformation
A final stretch of the colon is born without nerve cells and cannot relax: the newborn does not pass meconium and the bowel above it swells.
Updated 2026-11-01
See it in 3D: Rectum · Sigmoid colon · Descending colon · Mesenteric and aortic plexuses · Anal canal
What it is
It is the congenital absence of ganglion cells in the nerve plexuses of the distal bowel wall, because neural crest cells do not complete their craniocaudal migration. The aganglionic segment, which always includes the rectum, stays contracted and causes a functional obstruction; the healthy colon above it dilates. It accounts for about a quarter of newborn bowel obstructions.
Embryological cause
- Enteric neurons come from neural crest, mainly vagal, which enters the foregut around week 4 and reaches the hindgut around week 7.
- If migration stops or the cells do not survive, the distal segment lacks the submucosal (Meissner) and myenteric (Auerbach) plexuses.
- Without neurons to relax it, the segment stays contracted and has no peristalsis; the proximal colon dilates (megacolon).
- Genes: RET, the most common, plus EDNRB, EDN3 and SOX10; syndromic forms such as Waardenburg syndrome type IV.
Markers
- RET
- EDNRB
- EDN3
- SOX10
- GDNF
How it presents
- A newborn who does not pass meconium in the first 24 to 48 hours, with abdominal distension and bilious vomiting.
- Older children: severe chronic constipation since birth and poor growth.
- Enterocolitis: fever, distension and explosive foul-smelling diarrhoea; it can be severe.
- More common in boys (3 to 4 times); associated with Down syndrome and other syndromes.
Diagnosis
- Suction rectal biopsy: no ganglion cells and hypertrophied nerve trunks; increased acetylcholinesterase staining.
- Contrast enema: narrow rectum and dilated colon, with a funnel-shaped transition zone.
- Anorectal manometry: the rectoanal inhibitory reflex is absent.
- X-ray: dilated loops with no air in the rectum.
Test yourself
Think of the answer, then tap the question to see it.
Which cell population fails in Hirschsprung disease?
The neural crest cells that form the enteric neurons; they do not complete their migration to the distal bowel.
Why is the rectum always involved?
Because migration is craniocaudal: the rectum is the last segment to be colonised, and the defect extends upward from there.
Which test confirms the diagnosis?
Suction rectal biopsy, showing absent ganglion cells in the submucosa.
Which gene is most often involved?
RET, which encodes a receptor tyrosine kinase needed for enteric neuron development.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- Neural crest cells and their derivatives
- Hindgut and cloaca: the urorectal septum and the pectinate line
- Anorectal malformations (imperforate anus)
- Primitive gut: foregut, midgut and hindgut and their arteries
- Jejunal and ileal atresia
Related conditions
Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given.
Sources: Embryology, Bowel (StatPearls Publishing (NCBI Bookshelf), 2023); Hirschsprung disease (MedlinePlus, U.S. National Library of Medicine, 2025); Hirschsprung disease: MedlinePlus Genetics (MedlinePlus, U.S. National Library of Medicine, 2018).
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Representative model, for educational purposes only.