Hirschsprung’s disease is a congenital condition characterized by the absence of ganglion cells in the submucosal (Meissner’s) and myenteric (Auerbach’s) plexuses of the distal bowel. This results in functional intestinal obstruction due to a lack of peristalsis in the affected segment.
Epidemiology
- Incidence: ~1 in 5,000 live births.
- Sex: 4:1 male-to-female ratio in short-segment disease. Long-segment disease is more common in females.
- Ethnicity: More prevalent in Caucasians than in Black or Asian populations.
- Familial cases: 5–10%; more likely in females and with longer aganglionic segments.
Etiology & Genetics
Hirschsprung's disease can be sporadic (80–90%) or familial (10–20%). It results from defective migration or differentiation of neural crest cells during embryogenesis.
Genetic Associations
| Gene | Chromosome | Inheritance |
|---|---|---|
| RET | 10q11.2 | Autosomal dominant (incomplete penetrance) |
| EDNRB | 13q22 | Autosomal recessive |
| EDN3 | 20q13 | Autosomal recessive |
Inheritance pattern:
- Long-segment: Often autosomal dominant.
- Short-segment: Typically autosomal recessive.
Pathophysiology
- Primary defect: Failure of neural crest cell migration into the distal gastrointestinal tract.
- Result: Absence of parasympathetic ganglion cells → loss of coordinated peristalsis → functional obstruction.
- Transition zone: Normal proximal bowel becomes dilated due to fecal stasis; distal aganglionic bowel is narrowed and contracted.
Associated Conditions
- Trisomy 21 (Down syndrome) – ~10% of affected children have Down syndrome.
- Waardenburg syndrome
- Congenital central hypoventilation syndrome (Ondine's curse)
- Anorectal malformations
- Genitourinary anomalies
Clinical Features
Neonatal Period
- Delayed passage of meconium >48 hours
- Abdominal distension
- Bilious vomiting
- Poor feeding
Infancy & Childhood
- Chronic constipation alternating with diarrhea
- Small, ribbon-like stools
- Visible peristalsis
- Failure to thrive
- Explosive expulsion of stool after rectal exam (“squirt sign”)
Complications
- Hirschsprung-associated enterocolitis (HAEC): potentially fatal, presents with fever, abdominal distension, and bloody diarrhea.
- Toxic megacolon
- Intestinal perforation
- Failure to thrive
Physical Examination
- Abdominal distension
- Palpable fecal masses
- Tight, empty rectum on digital rectal exam
- Squirt sign: explosive release of gas/stool after digital rectal stimulation
Diagnosis
Imaging
- Abdominal X-ray
- Dilated loops of bowel
- Air-fluid levels
- Lack of gas in the rectum
- Contrast Enema (Barium enema)
- Reveals a narrow aganglionic distal segment with proximal megacolon
- Transition zone is diagnostic
- Anorectal Manometry
- Absent rectoanal inhibitory reflex (RAIR)
Biopsy (Gold Standard)
- Rectal suction biopsy:
- No ganglion cells
- Hypertrophic nerve trunks
- Positive acetylcholinesterase staining
- Full-thickness biopsy (if suction biopsy inconclusive)
Differential Diagnosis
- Meconium plug syndrome
- Small left colon syndrome
- Anorectal malformations
- Intestinal atresia
- Sepsis
- Hypothyroidism
- Pseudo-obstruction
Management
Initial Stabilization
- IV fluids, electrolyte correction
- Rectal decompression with saline enemas
- Broad-spectrum antibiotics for suspected enterocolitis
Definitive Surgical Treatment
Goals
- Resect aganglionic segment
- Restore bowel continuity with functional ganglionic bowel
Surgical Techniques
- Swenson Procedure
- End-to-end anastomosis after resecting aganglionic rectum and colon.
- Duhamel Procedure
- Retrorectal pull-through with side-to-side anastomosis between ganglionic bowel and rectal stump.
- Soave Procedure
- Pull-through of ganglionic mucosa through the muscular cuff of the rectum (submucosal endorectal dissection).
Staged vs. Single-stage repair
- Staged (especially in sick neonates): Initial colostomy followed by pull-through.
- Single-stage: Definitive surgery without prior stoma, increasingly common in stable patients.
Prognosis
- Excellent with early diagnosis and surgical correction.
- Long-term complications:
- Persistent constipation or soiling
- Enterocolitis (may recur post-op)
- Fecal incontinence (rare, more common in long-segment disease)
High-Yield
| Feature | Hirschsprung’s Disease |
|---|---|
| Cause | Congenital absence of ganglion cells |
| Main Symptom | Failure to pass meconium in first 48 hours |
| Diagnosis | Rectal suction biopsy (gold standard) |
| Imaging | Barium enema → transition zone |
| Reflex Absent | Rectoanal inhibitory reflex |
| Associated Syndromes | Down syndrome, Waardenburg, Ondine’s curse |
| Management | Surgical resection and pull-through |
