FCPS Paediatrics TOACS · Interactive Station

✅ Candidate's structured answer:
• X-ray findings: Dilated, uneven small bowel loops (obstruction). Absence of air-fluid levels on supine film (but present on upright). “Soap-bubble” or “ground-glass” appearance due to inspissated meconium mixed with air. No rectal gas. Calcifications may be seen if in-utero perforation (complicated meconium ileus).
• Diagnosis: Meconium ileus – a neonatal intestinal obstruction caused by thick, tenacious meconium impacted in the distal ileum.

✅ Candidate's answer:
• Meconium ileus is caused by abnormally thick, viscid, tenacious meconium that obstructs the distal ileum (usually terminal ileum).
• The cause is exocrine pancreatic insufficiency due to cystic fibrosis (CF) – lack of pancreatic enzymes (trypsin, chymotrypsin) leads to incomplete digestion of proteins in meconium, making it thick and sticky.
• CF is an autosomal recessive disorder of the CFTR gene (chromosome 7q31.2).
• Approximately 10-15% of newborns with CF present with meconium ileus. Conversely, 98% of infants with meconium ileus have CF.
• The obstruction is usually in the distal ileum, with proximal bowel dilated and distal colon unused (microcolon).

✅ Candidate's answer:
• Meconium ileus (CF-related).
• Meconium plug syndrome – distal colonic obstruction by meconium plug; often associated with Hirschsprung, maternal diabetes, prematurity, magnesium sulfate. Contrast enema is diagnostic and therapeutic.
• Hirschsprung disease (congenital aganglionic megacolon) – presents with delayed meconium passage, abdominal distension. Suction rectal biopsy is diagnostic.
• Small bowel atresia (duodenal, jejunal, ileal) – X-ray may show air-fluid levels, triple bubble sign (duodenal), or no meconium calcifications.
• Malrotation with midgut volvulus – sudden onset bilious vomiting, requires urgent upper GI contrast.
• Necrotizing enterocolitis (NEC) – occurs later, with systemic illness, pneumatosis.

✅ Candidate's answer:
• Simple meconium ileus (80%): Mechanical obstruction of the distal ileum by thick meconium without perforation. Proximal bowel is dilated, distal colon is unused (microcolon). The infant presents with abdominal distension and failure to pass meconium, but is otherwise stable.
• Complicated meconium ileus (20%): In-utero complications: volvulus, atresia, perforation, meconium peritonitis, or pseudocyst formation. Presents with abdominal calcifications on X-ray, ascites, respiratory distress (if massive ascites), and more severe illness. Requires urgent surgery.
• Distinction is important for management: simple may be managed with contrast enema; complicated requires laparotomy.

✅ Candidate's answer:
• Diagnostic: Contrast enema (water-soluble, e.g., diatrizoate (Gastrografin) or diluted barium) shows a microcolon (unused colon) and filling defects (meconium pellets) in the terminal ileum.
• Therapeutic (for simple meconium ileus): Hyperosmolar water-soluble contrast (Gastrografin) draws fluid into the bowel lumen, loosening the inspissated meconium and relieving obstruction.
- Success rate: 50-70% with a single enema.
- Procedure: Under fluoroscopy, contrast is infused gently; may require repeated attempts.
- Risks: Fluid shifts (hypovolemia), hypernatremia, bowel perforation, volvulus. IV hydration is mandatory before, during, and after.
- If successful, the infant passes meconium and symptoms resolve.

✅ Candidate's answer:
• Indications for surgery:
1️⃣ Failed contrast enema (persistent obstruction after 1-2 attempts).
2️⃣ Complicated meconium ileus (volvulus, atresia, perforation, calcifications, peritonitis).
3️⃣ Clinical deterioration (perforation, sepsis, peritonitis).
• Surgical procedures:
- Laparotomy with enterotomy and irrigation: The distal ileum is opened, and thick meconium is flushed with saline or N-acetylcysteine (Mucomyst).
- Bowel resection and primary anastomosis – if atresia, volvulus, or necrotic bowel.
- Temporary enterostomy (double-barrel stoma) – for severe cases with high risk of anastomotic leak.
- Bowel preservation is critical – avoid extensive resection to prevent short bowel syndrome.

✅ Candidate's answer:
• Sweat chloride test (gold standard): Pilocarpine iontophoresis. Positive >60 mmol/L (or >30-59 mmol/L intermediate, repeat).
• Immunoreactive trypsinogen (IRT) on newborn screening – elevated in CF (but meconium ileus may falsely elevate).
• CFTR gene mutation analysis – identifies common mutations (e.g., F508del).
• Fecal elastase-1 – low (<100 µg/g) indicates pancreatic insufficiency.
• Nasal potential difference (NPD) – specialized test.
• Note: Almost all infants with meconium ileus have CF; confirmatory testing should be done urgently.

✅ Candidate's structured answer:
1️⃣ NPO (nil per oral) – nothing by mouth.
2️⃣ Nasogastric (NG) tube to continuous suction – decompress stomach, prevent aspiration.
3️⃣ IV fluids and correction of dehydration/electrolytes – may have significant third-space losses.
4️⃣ Serial abdominal examinations and X-rays – monitor for perforation, peritonitis, or progression.
5️⃣ Broad-spectrum IV antibiotics (ampicillin + gentamicin + metronidazole) – to cover translocation from obstructed bowel.
6️⃣ Pediatric surgery and gastroenterology consultation.
7️⃣ Water-soluble contrast enema (Gastrografin) – if simple uncomplicated meconium ileus suspected. Ensure IV hydration before procedure.
8️⃣ After resolution, confirm CF diagnosis and initiate pancreatic enzyme replacement therapy (PERT).

✅ Candidate's answer:
• Start after resolution of obstruction and when enteral feeds are established.
• Dose: Lipase 1,000-2,000 U/kg/meal (or 2,000-4,000 U/kg/day).
• Formulation: Pancrelipase (Creon, Zenpep) – enteric-coated microspheres. Sprinkled on applesauce or formula. Do NOT crush or chew.
• Give with all meals and snacks (including breastmilk or formula containing fat).
• Monitor for fibrosing colonopathy (high doses) – constipation, abdominal pain, strictures.
• Also start fat-soluble vitamins (ADEK) and salt supplementation.
• Refer to CF multidisciplinary team.

✅ Candidate's answer:
• Multidisciplinary CF team: Pulmonology, gastroenterology, nutrition, physiotherapy, social work.
• Pancreatic enzymes and fat-soluble vitamins (ADEK).
• Respiratory management: Chest physiotherapy, airway clearance (flutter, vest), inhaled dornase alfa (Pulmozyme), hypertonic saline, bronchodilators. Vaccinations (including influenza, pneumococcal, RSV prophylaxis).
• CFTR modulators (e.g., elexacaftor/tezacaftor/ivacaftor – Trikafta): For eligible mutations (F508del). Dramatically improve pulmonary and GI outcomes.
• Nutrition: High-calorie diet, monitor growth, prevent meconium ileus recurrence.
• Monitor complications: Distal intestinal obstruction syndrome (DIOS) – partial obstruction with thickened stool; treat with Gastrografin enema or oral PEG.
• Genetic counseling for parents.

✅ Candidate's answer:
• Early complications:
- Bowel perforation → peritonitis, sepsis.
- Volvulus → bowel necrosis, short bowel syndrome.
- Electrolyte disturbances (hyponatremia, hypernatremia after contrast enema).
- Failure of contrast enema → need for laparotomy.
- Postoperative: anastomotic leak, wound infection, adhesions.
• Late complications:
- Short bowel syndrome (if massive resection).
- Distal intestinal obstruction syndrome (DIOS) – recurrent partial obstruction in older children with CF, managed with oral PEG or Gastrografin enema.
- Nutritional failure, failure to thrive.
- CF pulmonary disease progression.

✅ Candidate's answer:
• Definition: Partial or complete obstruction of the distal small bowel (ileocecal region) by inspissated fecal material in a patient with CF (occurs after infancy).
• Presentation: Abdominal pain, distension, palpable fecal mass in right lower quadrant, vomiting, decreased stool output.
• Risk factors: Inadequate pancreatic enzymes, dehydration, poor dietary fat intake, older age.
• Management:
- Acute DIOS: Oral polyethylene glycol (PEG) 3350 (MiraLax) or Gastrografin enema (if complete obstruction). IVF, NPO, NG suction if severe.
- Prevention: Adequate enzyme dosing, high fluid intake, regular use of PEG or lactulose.
- Rarely requires surgery (laparotomy with enterotomy).

✅ Candidate's structured answer:
• “Your baby has a blockage of the bowel from thick, sticky meconium (meconium ileus). This is a medical emergency, but we can treat it.”
• “Almost all infants with this condition have an underlying genetic disease called cystic fibrosis (CF). CF affects the lungs and digestive system. We will confirm this with a sweat test and genetic testing.”
• “The bowel obstruction can often be treated without surgery by doing a contrast enema (a liquid X-ray study that can also wash out the plug). If that fails, your baby will need an operation.”
• “Even if surgery is needed, most babies do very well. The bowel usually works normally after recovery.”
• “If CF is confirmed, your baby will need lifelong daily treatment: pancreatic enzymes with all feeds, fat-soluble vitamins, salt, and regular chest physiotherapy. There are also new CFTR modulator drugs that dramatically improve outcomes.”
• “This is not your fault – CF is inherited, but you had no way of knowing. A genetics counselor will explain recurrence risks for future pregnancies (25% if both parents are carriers).”
• “We have a team of CF specialists who will support your family for years to come. Many people with CF live full, active lives today.”

✅ Candidate's answer:
• Cystic fibrosis is an autosomal recessive disorder. If both parents are carriers, the recurrence risk for each future pregnancy is 25% (1 in 4).
• 50% chance of being a carrier (asymptomatic), 25% chance of being unaffected non-carrier.
• Carrier testing for parents – if both identified as carriers, prenatal diagnosis is possible via chorionic villus sampling (CVS) or amniocentesis.
• Preimplantation genetic diagnosis (PGD) is also available.
• Counseling: “There is a 1 in 4 chance that a future child will have CF. We can offer genetic counseling and prenatal testing for subsequent pregnancies.”