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Hirschsprung disease
In Hirschsprung disease ganglion cells are missing from the bowel wall continuously from the rectum upwards, the affected segment does not relax and behaves as an obstruction — and the diagnosis is made by a rectal biopsy showing absent ganglion cells.
Why it matters in the exam
The classic picture: a term newborn who has not passed meconium in the first 48 hours, a distended abdomen, vomiting, and an "explosive" release of gas and stool after a rectal examination. Later in life — severe constipation from infancy with poor growth. The exam asks about the mechanism (failure of neural crest cell migration from above downwards), the common segment (rectosigmoid, about 75%–80%), the link with Down syndrome and RET, the diagnostic test and the dangerous complication — enterocolitis.
Diagnosis: a suction rectal biopsy above the dentate line — absent ganglion cells, hypertrophic nerve fibres and loss of calretinin staining. A contrast enema shows a transition zone between a narrow and a dilated segment and a reversed rectosigmoid ratio (rectum narrower than the sigmoid), but the transition zone may not be seen in total colonic Hirschsprung disease. On manometry the rectoanal inhibitory reflex (RAIR) is absent.
Enterocolitis (HAEC) can occur before and after surgery: fever, distension, foul explosive diarrhoea and sometimes shock; treatment — rectal washouts, fluids, broad-spectrum antibiotics including anaerobic cover and decompression. Surgical treatment is resection of the aganglionic segment and pull-through of normal bowel to the anus (Swenson, Soave or Duhamel), today mostly by a transanal approach; in a sick child or long-segment disease a stoma in ganglionated bowel comes first.
About 10% of children with Hirschsprung disease have Down syndrome, and RET changes are more common in familial and long-segment cases. Clinically Hirschsprung disease must be told apart from functional constipation: in functional constipation the rectum is full of stool, there is withholding and soiling, and the problem usually starts after toilet training.
Key points
- Continuous absence of ganglion cells from the rectum upwards.
- No meconium in 48 hours in a term newborn.
- Diagnosis by suction rectal biopsy; calretinin negative.
- Enterocolitis is the dangerous complication, before and after surgery.
- Treatment: pull-through of ganglionated bowel.
Summary table
| Topic | Typical finding | Note |
|---|---|---|
| Presentation | No meconium in 48 hours, distended abdomen | Later: constipation from infancy and poor growth |
| Contrast enema | Transition zone, reversed rectosigmoid ratio | May be normal in total colonic disease |
| Rectal biopsy | No ganglion cells, hypertrophic nerves, calretinin negative | The diagnostic test |
| Manometry | Absent RAIR | Useful in older children |
| Enterocolitis | Fever, explosive diarrhoea, distension | Washouts, antibiotics and decompression |
| Surgery | Pull-through of normal bowel | Stoma first in a sick child |
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Sources
- APSA Hirschsprung Disease Interest Group: Guidelines for the diagnosis and management of Hirschsprung-associated enterocolitis, 2017 — Diagnosis and treatment of enterocolitis
- Holcomb and Ashcraft's Pediatric Surgery, 7th edition (2019) — Hirschsprung Disease
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.