Hirschsprung Disease
On this page
Direct answer
Hirschsprung disease is congenital aganglionosis of the distal bowel from failure of neural crest migration, producing a tonically contracted segment with proximal functional obstruction and megacolon. The flag in a term neonate is delayed passage of meconium beyond 48 hours with distension and bilious vomiting; older infants and children show chronic constipation, failure to thrive and a child who has never soiled. Diagnosis is by suction rectal biopsy — absent ganglion cells, hypertrophic nerve trunks, raised acetylcholinesterase — supported by anorectal manometry showing absence of the rectoanal inhibitory reflex. Definitive treatment is a pull-through operation — Swenson, Duhamel or Soave — after stabilisation, with Hirschsprung-associated enterocolitis the principal cause of death.
What you must remember
- Genetics and epidemiology: incidence around 1 in 5000 live births, male predominance roughly 4:1; RET proto-oncogene variants account for a share of cases, and about 5-10% have Down syndrome.
- Length of disease: rectosigmoid (short segment) in about 75-80%, long-segment colonic disease around 10%, total colonic aganglionosis in 5-8% — the length defines the operation.
- Diagnostic gold standard: suction rectal biopsy taken at least 1 cm above the dentate line (the distal 1 cm is physiologically hypoganglionic), showing absent submucosal ganglion cells, hypertrophied nerve trunks and raised acetylcholinesterase.
- Screening test: anorectal manometry with absent rectoanal inhibitory reflex (no internal sphincter relaxation on rectal balloon distension).
- Barium enema: shows the funnels-shaped transition zone between dilated ganglionic colon and narrow aganglionic rectum, but may be unhelpful in small neonates.
- Operations: Swenson (endorectal-free pull-through and direct anastomosis), Duhamel (retrorectal pull-through leaving an aganglionic- plus ganglionic side-to-side pouch), Soave (endorectal mucosectomy pull-through within the aganglionic muscular cuff); all now often performed transanally, with or without a preliminary levelling colostomy.
- Levelling colostomy: the stoma is sited on ganglionic bowel confirmed by intraoperative frozen-section biopsy.
- Enterocolitis (HAEC): fever, explosive diarrhoea (often paradoxically bloody) and a toxic distended abdomen, before or after pull-through — treated with rectal washouts, decompression, broad-spectrum antibiotics and metronidazole; the leading killer.
Confirming the diagnosis, then correcting it
Sequence the pathway as the examiners do. A term baby has not passed meconium at 50 hours; a finger stimulus or gentle rectal examination triggers an explosive release of gas and meconium — the classic immediate clue — and the baby returns with distension within days. Anorectal manometry shows no relaxation of the internal sphincter on balloon inflation: absent RAIR. Suction rectal biopsy at 1, 2 and 3 cm above the dentate line shows no ganglion cells and thick acetylcholinesterase-positive trunks: diagnosis closed. A contrast enema maps the transition zone but never overrides histology. Correction may be staged or primary: the modern default is a primary transanal pull-through in a well baby, with a levelling colostomy reserved for late presentation, enterocolitis, malnutrition or a long segment — the colostomy level chosen on frozen section, because pulling through aganglionic bowel is the catastrophe of this surgery. Family counselling covers the recurrence risk in siblings and the long-run expectations of soiling and constipation, which persist for a substantial minority.
Where marks are lost
The first error is biopsy depth: sampling within 1 cm of the dentate line reads "aganglionic" in a normal child because that zone is physiologically hypoganglionic, and the false positive lands a healthy baby in theatre. The second is trusting the neonatal contrast enema — a transition zone may be absent in the first weeks, so a normal enema never excludes the disease when histology is pending. The third is misreading enterocolitis as simple gastroenteritis: a post-pull-through child with fever and foul diarrhoea has HAEC until washouts and antibiotics say otherwise, and a plain film may show the jagged mucosal "saw-tooth" outline of the aganglionic segment. The fourth confuses the operations — remember them by their different failures: Swenson's pelvic dissection risks continence nerves, Duhamel leaves a blind spurring pouch with faecal stasis, Soave leaves a muscular cuff that can stricture. Finally, total colonic aganglionosis is the answer to the "baby with normal rectal biopsy but whole-bowel dilatation" variant — level of disease above the sampled segment.
Frequently asked questions
Which investigation is the gold standard for Hirschsprung disease?
Suction rectal biopsy at least 1 cm above the dentate line, showing absent ganglion cells with hypertrophic acetylcholinesterase-positive nerve trunks.
What does anorectal manometry show in Hirschsprung disease?
Absence of the rectoanal inhibitory reflex — the internal anal sphincter fails to relax on rectal balloon distension — making it a useful screening test.
Which finding raises suspicion in a neonate?
Failure to pass meconium within 48 hours of birth in a term infant, often with explosive discharge after rectal stimulation.
What is Hirschsprung-associated enterocolitis?
The life-threatening complication of abdominal distension, fever and foul often-bloody diarrhoea from stasis and bacterial overgrowth, treated with washouts, decompression and antibiotics.
How do the Swenson, Duhamel and Soave operations differ?
Swenson resects the aganglionic segment and anastomoses colon to the low rectum, Duhamel pulls ganglionic colon through a retrorectal track, and Soave pulls it through a mucosectomised aganglionic cuff.