FCPS TOACS Mock Test · Meconium Ileus

❓ Q1. Describe the findings on the abdominal radiograph. What is the most likely diagnosis?

✅ Model Answer:
• X-ray findings: Dilated, uneven small bowel loops (obstruction). Absence of air-fluid levels on supine film. "Soap-bubble" or "ground-glass" appearance due to inspissated meconium mixed with air. No rectal gas.
• Diagnosis: Meconium ileus – neonatal intestinal obstruction caused by thick, tenacious meconium impacted in distal ileum.

❓ Q2. Explain the pathophysiology of meconium ileus. What is the underlying systemic condition?

✅ Model Answer:
• Caused by abnormally thick, viscid meconium obstructing distal ileum.
• Underlying condition: Exocrine pancreatic insufficiency due to cystic fibrosis (CF) – lack of pancreatic enzymes (trypsin, chymotrypsin) → incomplete digestion of meconium proteins.
• CF is autosomal recessive (CFTR gene, chromosome 7q31.2).
• 10-15% of CF newborns present with meconium ileus. Conversely, 98% of meconium ileus infants have CF.

❓ Q3. What are the differential diagnoses for a neonate with bilious vomiting, abdominal distension, and failure to pass meconium?

✅ Model Answer:
• Meconium ileus (CF-related)
• Meconium plug syndrome (Hirschsprung, maternal diabetes, prematurity, MgSO₄)
• Hirschsprung disease (congenital aganglionic megacolon)
• Small bowel atresia (duodenal, jejunal, ileal)
• Malrotation with midgut volvulus (sudden onset, urgent)
• Necrotizing enterocolitis (later onset, systemic illness)

❓ Q4. What is the difference between simple and complicated meconium ileus?

✅ Model Answer:
• Simple (80%): Mechanical obstruction only, no perforation. Proximal bowel dilated, distal microcolon. Stable presentation.
• Complicated (20%): In-utero volvulus, atresia, perforation, meconium peritonitis, or pseudocyst. Presents with abdominal calcifications on X-ray, ascites, more severe illness. Requires urgent surgery.

❓ Q5. What is the role of a contrast enema in meconium ileus? Describe the typical findings.

✅ Model Answer:
• Diagnostic: Shows microcolon (unused colon) and filling defects (meconium pellets) in terminal ileum.
• Therapeutic (simple meconium ileus): Hyperosmolar water-soluble contrast (Gastrografin) draws fluid into bowel → loosens meconium. Success rate 50-70%.
• Risks: Fluid shifts (hypovolemia), hypernatremia, bowel perforation, volvulus. IV hydration MANDATORY before, during, and after.

❓ Q6. When is surgery indicated in meconium ileus? What procedures are performed?

✅ Model Answer:
• Indications: Failed contrast enema (1-2 attempts), complicated meconium ileus (volvulus, atresia, perforation, calcifications), clinical deterioration.
• Procedures: Laparotomy with enterotomy and irrigation (flush with saline or N-acetylcysteine), bowel resection + primary anastomosis (if atresia/necrosis), temporary enterostomy (double-barrel stoma) for severe cases. Bowel preservation critical to avoid short bowel syndrome.

❓ Q7. How is cystic fibrosis diagnosed in a newborn with meconium ileus?

✅ Model Answer:
• Sweat chloride test (gold standard): >60 mmol/L positive.
• Immunoreactive trypsinogen (IRT) – elevated on newborn screen.
• CFTR gene mutation analysis (e.g., F508del).
• Fecal elastase-1 (<100 µg/g) indicates pancreatic insufficiency.
• Note: Almost all infants with meconium ileus have CF – urgent confirmatory testing.

❓ Q8. What is your immediate management of this infant with suspected meconium ileus?

✅ Model Answer:
1. NPO (nil per oral).
2. Nasogastric (NG) tube to continuous suction.
3. IV fluids – correct dehydration/electrolytes (third-space losses).
4. Serial abdominal exams and X-rays.
5. Broad-spectrum IV antibiotics (ampicillin + gentamicin + metronidazole).
6. Pediatric surgery and gastroenterology consultation.
7. Water-soluble contrast enema (Gastrografin) if simple meconium ileus suspected – ensure IV hydration before.
8. After resolution, confirm CF diagnosis and initiate pancreatic enzyme replacement therapy (PERT).

❓ Q9. When and how is pancreatic enzyme replacement therapy (PERT) initiated in a neonate with CF presenting with meconium ileus?

✅ Model Answer:
• Start after resolution of obstruction and when enteral feeds established.
• Dose: Lipase 1,000-2,000 U/kg/meal (2,000-4,000 U/kg/day).
• Formulation: Pancrelipase (Creon, Zenpep) – enteric-coated microspheres. Sprinkle on applesauce or formula. Do NOT crush or chew.
• Give with all meals/snacks containing fat.
• Also start fat-soluble vitamins (ADEK) and salt supplementation.

❓ Q10. What is the long-term management for an infant diagnosed with cystic fibrosis after meconium ileus?

✅ Model Answer:
• Multidisciplinary CF team: Pulmonology, gastroenterology, nutrition, physiotherapy, social work.
• Pancreatic enzymes + fat-soluble vitamins (ADEK).
• Respiratory management: Chest physiotherapy, airway clearance, inhaled dornase alfa, hypertonic saline, bronchodilators, vaccinations.
• CFTR modulators (e.g., Trikafta) for eligible mutations (F508del).
• High-calorie diet, monitor growth.
• Monitor complications: Distal intestinal obstruction syndrome (DIOS) – treat with oral PEG or Gastrografin enema.
• Genetic counseling for parents.

❓ Q11. What is DIOS? How does it present and how is it managed?

✅ Model Answer:
• Distal intestinal obstruction syndrome (DIOS): Partial/complete obstruction of distal small bowel (ileocecal region) by inspissated fecal material in CF patients (occurs after infancy).
• Presentation: Abdominal pain, distension, palpable fecal mass in RLQ, vomiting, decreased stool output.
• Management: Oral polyethylene glycol (PEG 3350) or Gastrografin enema (if complete obstruction). IVF, NPO, NG suction if severe. Prevention: adequate enzyme dosing, high fluid intake, regular PEG/lactulose.

❓ Q12. How will you counsel the parents of this infant after the diagnosis of meconium ileus and suspected cystic fibrosis?

✅ Model Answer:
• “Your baby has meconium ileus – bowel blockage from thick meconium. This is treatable.”
• “Almost all infants with this have cystic fibrosis (CF) – a genetic disease affecting lungs/digestive system. We will confirm with sweat test/genetics.”
• “The obstruction can often be treated with a contrast enema (washout). If that fails, surgery is needed. Most babies do very well.”
• “If CF confirmed, your baby needs lifelong: pancreatic enzymes with feeds, fat-soluble vitamins, salt, chest physiotherapy, and new CFTR modulator drugs (dramatically improve outcomes).”
• “This is not your fault – CF is inherited. A genetics counselor will explain recurrence risks (25% if both parents carriers). Many people with CF live full, active lives today.”

⚕️ FCPS MCPS MD Paediatrics TOACS · Mock Test