Hirschsprung’s disease is a congenital disorder characterised by the absence of ganglion cells (aganglionosis) in the Meissner and Auerbach plexus of a segment of the distal colon. This is thought to be due to the failure of neural crest cell migration. Aganglionosis leads to chronic functional obstruction. It always extends the distal rectum and can extend proximally for variable lengths.
It affects boys more than girls.
| Type | Description |
|---|---|
| Short-segment disease (80%) | Affects the rectosigmoidal area |
| Long-segment disease (15 – 20%) | Extends proximally to the sigmoid |
| Total colonic aganglionosis (< 5%) | Affects the entire colon. Can involve the small intestine. |
| Zonal or skip-type (very rare) | Segmental involvement with mixed ganglionic and aganglionic segment |
Functional classification
| Classification | Description |
|---|---|
| Classical Hirschsprung’s disease | Aganglionosis + delayed passage of meconium and obstruction |
| Hirschsprung’s disease variants (Dysganglionosis spectrum) | |
| Intestinal neuronal dysplasia | Hyperplastic ganglia with increased AChE activity |
| Hypoganglionosis | A reduced number of ganglion cells |
| Internal anal sphincter achalasia | Normal ganglia with absent rectoanal inhibitory reflex (RAIR) |
| Immature ganglia | This is seen in neonates. It can mimic Hirschsprung’s disease |
- Associated conditions
- Down syndrome (10% of Hirschsprung’s disease cases)
- Multiple endocrine neoplasia type 2 (MEN2A/B)
- Waardenburg syndrome (piebaldism, deafness, aganglionosis)
- Congenital central hypoventilation syndrome (Ondine’s curse)
- Pathophysiology
- The enteric nervous system is derived from neural crest cells, which migrate rostrocaudal.
- Disrupted signaling → failure of neural crest cell migration, proliferation, or differentiation at weeks 5 – 12 of gestation → aganglionosis in the distal bowel
- Consequences of aganglionosis
- Loss of inhibitory neurons → failure of relaxation
- Unopposed excitatory activity due to persistent ACh release → tonic contraction of the aganglionic segment
- Functional obstruction → progressive dilation of the proximal segment → megacolon
- Absent recto-anal inhibitory reflex (RAIR – internal sphincter remains contracted when the rectum is distended)
- Signs and symptoms
- Failure to pass meconium
- Abdominal distention
- Reluctance to fed
- Bouts of alternating constipation and diarrhoea
- Constipation is common in older children
- Hirschsprung-associated enterocolitis (sepsis and toxic megacolon)
- Fever
- Bloody stool
- Explosive diarrhoea
- Physical examination
- Digital rectal examination
- Empty rectal vault
- Release of stool or flatus – “squirt sign.”
- Digital rectal examination
- Differentials
- Meconium ileus
- Small left colon syndrome
- Functional constipation
- Investigations
- Abdominal X-Ray
- Multiple loops of dilated bowel due to distal functional obstruction
- Air-fluid levels
- Paucity of rectal gas
- Contrast enema
- Narrow bowel segment (aganglionic)
- Dilated bowel segment (proximal to aganglionic region due to fecal accumulation)
- Transition zone (occurs later in life)
- Delayed evacuation of contrast (24 hours)
- Anorectal manometry
- Absent rectoanal inhibitory reflex (RAIR), i.e., failure of internal anal sphincter relaxation
- Rectal suction biopsy or full-thickness biopsy – This is the most accurate test (gold standard)
- Absence of ganglion cells in the submucosal (Meissner) plexus
- Hypertrophied nerve trunks
- Increased acetylcholinesterase activity
- Screen for associated conditions
- Abdominal X-Ray
- Treatment
- Nil per os
- Intravenous fluids
- Nasogastric tube for decompression
- Rectal irrigations for bowel decompression
- Antibiotics for Hirschsprung-associated enterocolitis
- Surgery (“Pull-through” procedures)
- Involves resection of the aganglionic segments and pulling down of the normal ganglionated bowel to the anus
- Diverting colostomy or ileostomy before primary repair or secondary take-down if there is enterocolitis or sepsis
- Complications
- Fecal retention
- Incontinence
- Anastomotic breakdown
- Stricture
- Hirschsprung-associated enterocolitis (HAEC)
- Total colonic aganglionosis
- Other general surgical complications
Pull-through procedures
| Procedure | Key Idea | Nota bene |
|---|---|---|
| Swenson procedure | Resection of aganglionic bowel + direct coloanal anastomosis | Carries an increased risk of pelvic nerve injury |
| Soave procedure | Pull-through of ganglionated bowel within a mucosal sleeve. This is the most commonly used procedure. | Has less nerve damage but carries the risk of cuff stricture or obstruction |
| Duhamel procedure | The bowel is pulled behind the rectum (side-to-side anastomosis) | Avoids pelvic disection, but can lead to fecal stasis within the blind pouch |