🩻 TOACS FCPS Station · Barium Enema in Hirschsprung Disease
📷 Barium Enema (Contrast Study)
🔍 Key radiographic features:
- ✓ Transition zone – abrupt caliber change between narrow aganglionic distal segment and dilated ganglionic proximal bowel
- ✓ Narrow, contracted rectum (aganglionic segment)
- ✓ Dilated proximal colon with fecal stasis
- ✓ Irregular mucosal pattern in aganglionic segment
- ✓ Delayed evacuation of contrast (persistent on 24-hour film)
📋 Clinical scenario (examiner prompt)
A 2‑day‑old term male newborn has failed to pass meconium since birth. He has progressive abdominal distention and bilious vomiting. Abdominal examination shows distended bowel loops with visible peristalsis. A barium enema is performed. The image shows a transition zone with a narrow aganglionic distal segment and a dilated proximal colon.
🧑⚕️ Examiner tasks · TOACS
1. Identify the diagnosis from the barium study and clinical context.
2. Describe the radiological findings (transition zone, narrow rectum, dilated proximal colon).
3. Explain the pathophysiology (aganglionosis, failure of neural crest migration).
4. Discuss the gold standard for diagnosis and management.
🎯 Expected answers (for examiners)
- • Diagnosis: Hirschsprung disease (congenital aganglionic megacolon)
- • X‑ray findings: Transition zone (narrow rectum → dilated proximal colon), irregular mucosa, delayed evacuation
- • Pathophysiology: Aganglionosis (failure of neural crest cell migration) → absent ganglion cells → tonic contraction → functional obstruction
- • Diagnosis: Rectal suction biopsy (gold standard) – absence of ganglion cells, AChE+
- • Management: NPO, NG decompression, rectal irrigations; definitive: pull-through procedure (Soave, Swenson, Duhamel)
⚡ Quick FCPS‑style MCQ
The transition zone on barium enema in Hirschsprung disease represents:
A. Junction between aganglionic and ganglionic bowel B. Site of intestinal perforation C. Area of meconium plug D. Site of volvulus📌 Topic summary ·
Congenital aganglionosis (failure of neural crest migration)
Transition zone, narrow rectum, dilated proximal colon
RET proto‑oncogene
Rectal suction biopsy (absence of ganglion cells)
Down syndrome (trisomy 21)
Pull‑through (Soave, Swenson, Duhamel)
| Feature | Hirschsprung Disease |
|---|---|
| Pathology | Absent ganglion cells in distal bowel |
| Barium enema | Transition zone, narrow rectum |
| Gold standard | Rectal suction biopsy (AChE+, absent ganglion cells) |
| Genetics | RET proto‑oncogene |
| Treatment | Pull‑through procedure |