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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Congenital aganglionosis — absence of parasympathetic ganglion cells in the distal bowel, always involving the rectum and extending proximally for a variable distance
- Failure to pass meconium within 48 hours of birth is the classic presenting feature (90% of cases)
- Short-segment disease (75%) involves rectosigmoid only; total colonic aganglionosis is rare
- Diagnosis: suction rectal biopsy showing absent ganglion cells and hypertrophied nerve trunks — gold standard
- Treatment: definitive pull-through surgery (e.g. Soave, Swenson, Duhamel) — resection of aganglionic segment and anastomosis of ganglionic bowel to anus
- Hirschsprung-associated enterocolitis (HAEC) is the most serious complication — can be life-threatening
Overview
Hirschsprung's disease results from failure of neural crest cell migration during embryonic development, leading to absence of ganglion cells in the myenteric and submucosal plexuses. The aganglionic segment is tonically contracted and cannot relax, causing functional obstruction. The rectum is always involved, and the aganglionosis extends proximally for a variable length. Short-segment disease (rectosigmoid) accounts for approximately 75% of cases. The proximal normally innervated bowel becomes dilated.
Epidemiology
Hirschsprung's disease occurs in approximately 1 in 5,000 live births. Male:female ratio is 4:1 for short-segment disease but 1:1 for total colonic disease. There is a strong association with Down syndrome (~5–10% of Hirschsprung's patients have trisomy 21). Other associations include MEN2 (RET proto-oncogene mutations), Waardenburg syndrome, and congenital central hypoventilation syndrome.
Clinical Features
Symptoms
Failure to pass meconium within 48 hours of birth (90%)
Abdominal distension in the neonatal period
Bilious vomiting
Chronic constipation from infancy — does NOT respond to standard laxatives
Failure to thrive
Explosive watery diarrhoea after rectal examination (squirt sign)
Signs
Abdominal distension with palpable faecal masses in proximal bowel
Empty rectum on digital rectal examination (despite constipation)
Explosive release of liquid stool and gas on withdrawal of examining finger
Signs of enterocolitis: fever, foul-smelling diarrhoea, abdominal tenderness, sepsis
Investigations
First-line
Suction rectal biopsyGold standard — shows absent ganglion cells and hypertrophied nerve trunks with acetylcholinesterase staining. Must be taken at least 2 cm above the dentate line
Second-line
Contrast enemaMay show transition zone between narrow aganglionic distal segment and dilated proximal bowel. Delayed 24 h films show retained contrast
Anorectal manometryAbsence of the normal rectoanal inhibitory reflex (RAIR) — the internal sphincter fails to relax on rectal distension
Specialist
Full-thickness rectal biopsyIf suction biopsy is inconclusive — performed under general anaesthesia
Management
BAPS paediatric surgical guidelines1
Initial management
- Rectal washouts to decompress the bowel
- IV fluids and NG decompression if presenting with obstruction
- Treat Hirschsprung-associated enterocolitis (HAEC) aggressively: IV antibiotics, rectal washouts, fluid resuscitation
2
Definitive surgery
- Pull-through procedure: resection of the aganglionic segment with anastomosis of normally innervated bowel to the anus
- Common techniques: Soave (endorectal), Swenson (full-thickness), Duhamel (retrorectal)
- Can be performed as single-stage primary pull-through in most cases
- Stoma formation may be needed if: severe enterocolitis, very dilated proximal bowel, total colonic disease
3
Long-term follow-up
- Monitor bowel function — continence issues, constipation, or soiling may persist
- HAEC can occur even after surgery — parents should be educated about warning signs
- Regular follow-up with paediatric surgeon
Complications
- Hirschsprung-associated enterocolitis (HAEC): Most serious complication — foul-smelling diarrhoea, abdominal distension, fever, sepsis. Can be life-threatening. Can occur before or after surgery
- Bowel perforation: From obstruction or enterocolitis
- Post-operative soiling and continence issues: May require bowel management programme
- Anastomotic stricture: May require dilatation
UKMLA Exam Tips
- 1Delayed passage of meconium (>48 h) + abdominal distension in a neonate = think Hirschsprung's
- 2Empty rectum on DRE despite constipation — distinguishes from functional constipation (which has faecal loading in rectum)
- 3Gold standard diagnosis: suction rectal biopsy showing ABSENT ganglion cells
- 4Associated with Down syndrome — ~5–10% of Hirschsprung's patients have trisomy 21
- 5HAEC is the most dangerous complication — can occur before or after surgery
- 6Unlike functional constipation, Hirschsprung's presents from birth and does not respond to standard laxatives
practicetest your knowledge on hirschsprung's diseaseApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — paediatrics and beyond.
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