FCPS Paediatrics TOACS · Interactive Station
🩺 Congenital Diaphragmatic Hernia (CDH) — X‑ray interpretation & management
📚 Paeds Online – paeds.online
⚕️ OBSERVED STATION · CPSP FORMAT · 8 MINUTES · SEPARATE TABS · X-RAY INCLUDED
📖 Problem-oriented Clinical Scenario + Chest X-ray
👶🏻 Clinical Scenario (read aloud – 2 min):
A 2-hour-old term infant is brought to the neonatal unit with severe respiratory distress immediately after birth. The baby was born via spontaneous vaginal delivery at 39 weeks to a primigravida mother with no significant antenatal history. On examination: respiratory rate 80/min, severe subcostal and intercostal retractions, grunting, and cyanosis in room air. The abdomen is scaphoid, and breath sounds are absent on the left side with heart sounds shifted to the right.
A chest X-ray is performed. The image is shown below.
Task: Interpret the chest X-ray, identify the abnormality, and discuss immediate management.
A 2-hour-old term infant is brought to the neonatal unit with severe respiratory distress immediately after birth. The baby was born via spontaneous vaginal delivery at 39 weeks to a primigravida mother with no significant antenatal history. On examination: respiratory rate 80/min, severe subcostal and intercostal retractions, grunting, and cyanosis in room air. The abdomen is scaphoid, and breath sounds are absent on the left side with heart sounds shifted to the right.
A chest X-ray is performed. The image is shown below.
Task: Interpret the chest X-ray, identify the abnormality, and discuss immediate management.
🔍 Figure: Anteroposterior chest X-ray showing gas-filled bowel loops in the left hemithorax, mediastinal shift to the right, and a scaphoid abdomen (classic findings of left-sided congenital diaphragmatic hernia – Bochdalek type).
Source: Uploaded X-ray image (PostImages).
Source: Uploaded X-ray image (PostImages).
💡 Examiner instruction (interactive): The candidate will be asked to interpret the X-ray, describe the findings, and then answer questions regarding prenatal predictors, delivery room management, ventilation strategy, surgical planning, and long-term follow-up.
🔍 Examiner Questions (interactive) – Click to reveal model answers
❓ Q1 (Examiner – X-ray interpretation): “Describe the findings on this chest X-ray. What is the most likely diagnosis?”
✅ Candidate's structured answer:
• X-ray findings: Gas-filled loops of bowel (stomach and small intestine) visible in the left hemithorax. The mediastinum is shifted to the right. There is a scaphoid abdomen (lack of abdominal gas).
• Diagnosis: Left-sided congenital diaphragmatic hernia (CDH) – most commonly Bochdalek hernia (posterolateral defect).
• Differential: Congenital cystic adenomatoid malformation (CCAM), eventration of diaphragm, pneumatocele (less likely).
• X-ray findings: Gas-filled loops of bowel (stomach and small intestine) visible in the left hemithorax. The mediastinum is shifted to the right. There is a scaphoid abdomen (lack of abdominal gas).
• Diagnosis: Left-sided congenital diaphragmatic hernia (CDH) – most commonly Bochdalek hernia (posterolateral defect).
• Differential: Congenital cystic adenomatoid malformation (CCAM), eventration of diaphragm, pneumatocele (less likely).
❓ Q2 (Examiner): “What are the key prenatal predictors of poor outcome in CDH, and what fetal interventions can improve survival?”
✅ Candidate's structured answer:
• O/E LHR (observed/expected lung-to-head ratio) <25% → severe pulmonary hypoplasia.
• Liver herniation into chest → worse prognosis.
• Polyhydramnios → risk of preterm delivery.
• Fetal intervention: FETO (fetoscopic tracheal occlusion) – balloon placed at 27-29 wk, removed at 34 wk.
• TOTAL trial: FETO improved survival in severe CDH from 15% to 40% (but increased PPROM & preterm birth).
• O/E LHR (observed/expected lung-to-head ratio) <25% → severe pulmonary hypoplasia.
• Liver herniation into chest → worse prognosis.
• Polyhydramnios → risk of preterm delivery.
• Fetal intervention: FETO (fetoscopic tracheal occlusion) – balloon placed at 27-29 wk, removed at 34 wk.
• TOTAL trial: FETO improved survival in severe CDH from 15% to 40% (but increased PPROM & preterm birth).
❓ Q3 (Examiner): “Describe your immediate delivery room management for this infant.”
✅ Candidate's structured answer:
1️⃣ Immediate intubation (ETT) – avoid bag-mask ventilation (distends stomach/bowel, worsens respiratory compromise).
2️⃣ Place orogastric tube (large bore, continuous suction) – decompress stomach.
3️⃣ Start gentle ventilation – PIP <25 cmH₂O, PEEP 3-5, rate 40-60, permissive hypercapnia (PaCO₂ 45-65).
4️⃣ Secure IV access, check glucose, calcium – may need inotropic support.
5️⃣ Early echocardiogram – assess PPHN, RV function, exclude structural cardiac anomalies (20% CDH have CHD).
6️⃣ Transfer to tertiary NICU (ECMO capable).
1️⃣ Immediate intubation (ETT) – avoid bag-mask ventilation (distends stomach/bowel, worsens respiratory compromise).
2️⃣ Place orogastric tube (large bore, continuous suction) – decompress stomach.
3️⃣ Start gentle ventilation – PIP <25 cmH₂O, PEEP 3-5, rate 40-60, permissive hypercapnia (PaCO₂ 45-65).
4️⃣ Secure IV access, check glucose, calcium – may need inotropic support.
5️⃣ Early echocardiogram – assess PPHN, RV function, exclude structural cardiac anomalies (20% CDH have CHD).
6️⃣ Transfer to tertiary NICU (ECMO capable).
❓ Q4 (Examiner): “What is your ventilation strategy in the first 48 hours to avoid lung injury?”
✅ Candidate's answer:
• ‘Gentle ventilation’ protocol: low peak inspiratory pressure (PIP <25), low rate, avoid volutrauma.
• Permissive hypercapnia (accept PaCO₂ up to 60-65 mmHg) with pH >7.20.
• Avoid hyperoxia – target SpO₂ 85-95% (pre-ductal).
• High-frequency oscillatory ventilation (HFOV) if PIP >25 required or persistent hypoxemia.
• Inhaled nitric oxide (iNO) for PPHN (though CDH may be less responsive).
• ECMO reserved for OI >40 or failure to maintain pH/PaO₂.
• ‘Gentle ventilation’ protocol: low peak inspiratory pressure (PIP <25), low rate, avoid volutrauma.
• Permissive hypercapnia (accept PaCO₂ up to 60-65 mmHg) with pH >7.20.
• Avoid hyperoxia – target SpO₂ 85-95% (pre-ductal).
• High-frequency oscillatory ventilation (HFOV) if PIP >25 required or persistent hypoxemia.
• Inhaled nitric oxide (iNO) for PPHN (though CDH may be less responsive).
• ECMO reserved for OI >40 or failure to maintain pH/PaO₂.
❓ Q5 (Examiner): “When do you perform surgical repair and what are the options?”
✅ Candidate's answer:
• Delay repair until after stabilization (usually 48h – 7 days) – once PPHN resolved, FiO₂ <0.5, minimal inotropes.
• Open repair (subcostal laparotomy) – primary closure if defect small; Gore-Tex patch for large defects.
• Minimally invasive (thoracoscopy/laparoscopy) – only for stable infants, not routine.
• If on ECMO, repair can be performed on ECMO or after decannulation depending on centre protocol.
• Post-operative complications: PPHN recurrence, chylothorax (thoracic duct injury), recurrence (~10%).
• Delay repair until after stabilization (usually 48h – 7 days) – once PPHN resolved, FiO₂ <0.5, minimal inotropes.
• Open repair (subcostal laparotomy) – primary closure if defect small; Gore-Tex patch for large defects.
• Minimally invasive (thoracoscopy/laparoscopy) – only for stable infants, not routine.
• If on ECMO, repair can be performed on ECMO or after decannulation depending on centre protocol.
• Post-operative complications: PPHN recurrence, chylothorax (thoracic duct injury), recurrence (~10%).
❓ Q6 (Examiner): “What long-term complications and follow-up are required for CDH survivors?”
✅ Candidate's answer:
• GERD (gastroesophageal reflux) >50% – may require fundoplication.
• Chronic lung disease – BPD, reactive airways, exercise intolerance.
• Pulmonary hypertension – monitor with echocardiogram, sildenafil if needed.
• Neurodevelopmental impairment – especially if ECMO used (hearing loss, CP, cognitive delay).
• Musculoskeletal – scoliosis, pectus excavatum.
• Follow-up: multidisciplinary clinic (respiratory, gastroenterology, developmental paediatrics, audiology).
• GERD (gastroesophageal reflux) >50% – may require fundoplication.
• Chronic lung disease – BPD, reactive airways, exercise intolerance.
• Pulmonary hypertension – monitor with echocardiogram, sildenafil if needed.
• Neurodevelopmental impairment – especially if ECMO used (hearing loss, CP, cognitive delay).
• Musculoskeletal – scoliosis, pectus excavatum.
• Follow-up: multidisciplinary clinic (respiratory, gastroenterology, developmental paediatrics, audiology).
🗣️ Examiner's probing / high-yield points:
• “What is FETO and what are its risks?” → Balloon occlusion of trachea; risks: PPROM (47%), preterm birth (75%), chorioamnionitis.
• “What is the TOTAL trial finding?” → FETO survival 40% vs 15% expectant in severe CDH (O/E LHR <25%).
• “What is the role of ECMO?” → For OI >40 or failure to oxygenate/ventilate despite optimal medical therapy.
• “What are contraindications to CDH repair?” → Active uncontrolled PPHN, severe coagulopathy, haemodynamic instability.
• “What is the recurrence rate after patch repair?” → ~10%, higher than primary repair.
• “What is FETO and what are its risks?” → Balloon occlusion of trachea; risks: PPROM (47%), preterm birth (75%), chorioamnionitis.
• “What is the TOTAL trial finding?” → FETO survival 40% vs 15% expectant in severe CDH (O/E LHR <25%).
• “What is the role of ECMO?” → For OI >40 or failure to oxygenate/ventilate despite optimal medical therapy.
• “What are contraindications to CDH repair?” → Active uncontrolled PPHN, severe coagulopathy, haemodynamic instability.
• “What is the recurrence rate after patch repair?” → ~10%, higher than primary repair.
📘 Congenital Diaphragmatic Hernia – Core Revision
🔍 Definition
Posterolateral defect (Bochdalek 90%, left 80-90%). Herniation of abdominal contents into thorax → pulmonary hypoplasia + PPHN.
Posterolateral defect (Bochdalek 90%, left 80-90%). Herniation of abdominal contents into thorax → pulmonary hypoplasia + PPHN.
📊 Prenatal prognosis
O/E LHR <25% → severe. Liver herniation → worse. FETO improves survival if severe.
O/E LHR <25% → severe. Liver herniation → worse. FETO improves survival if severe.
💊 Fetal therapy (FETO)
Balloon occlusion of trachea (27-29 wk) → removed at 34 wk. TOTAL trial: survival 40% vs 15%.
Balloon occlusion of trachea (27-29 wk) → removed at 34 wk. TOTAL trial: survival 40% vs 15%.
🩺 Delivery room
Intubate, OG tube, NO bag-mask. Gentle ventilation (PIP <25), permissive hypercapnia.
Intubate, OG tube, NO bag-mask. Gentle ventilation (PIP <25), permissive hypercapnia.
⚕️ Surgical repair
Delayed (48h – 7 days). Primary closure or Gore-Tex patch. Recurrence ~10% (patch higher).
Delayed (48h – 7 days). Primary closure or Gore-Tex patch. Recurrence ~10% (patch higher).
📈 Long-term
GERD (>50%), chronic lung disease, PPHN, neurodevelopmental impairment, scoliosis.
GERD (>50%), chronic lung disease, PPHN, neurodevelopmental impairment, scoliosis.
🗣️ Candidate’s role-play & examiner feedback
💬 To the candidate (role‑play): You will be asked the 6 questions from the Examiner Q&A tab (including X-ray interpretation). Provide concise, evidence‑based answers. Examiner may interrupt for clarification. Use structured points.
📝 Examiner Marking Grid (CDH – TOACS station):
- ✅ Correctly identifies X-ray findings (bowel loops in chest, mediastinal shift)
- ✅ Recognises O/E LHR <25% + liver herniation as poor prognostic markers
- ✅ Describes FETO (timing, risks, TOTAL trial survival benefit)
- ✅ Immediate DR management: intubate, OG tube, avoid bag-mask
- ✅ Gentle ventilation / permissive hypercapnia / HFOV
- ✅ Timing of repair (after stabilisation, not emergency)
- ✅ Long-term GERD, PPHN, neurodevelopmental follow-up
⭐ High-yield CDH pearls for TOACS:
• Chest X-ray hallmark: Gas-filled bowel loops in hemithorax + contralateral mediastinal shift + scaphoid abdomen.
• Do NOT bag-mask ventilate → leads to massive gastric distension → worse respiratory compromise.
• OG tube on continuous suction is life‑saving.
• FETO improves survival but increases PPROM (47% vs 11%).
• Associated anomalies – cardiac (20%), chromosomal (10-15%), Beckwith-Wiedemann, Fryns.
• Neurodevelopmental issues common – especially with ECMO; must refer to early intervention.
• Chest X-ray hallmark: Gas-filled bowel loops in hemithorax + contralateral mediastinal shift + scaphoid abdomen.
• Do NOT bag-mask ventilate → leads to massive gastric distension → worse respiratory compromise.
• OG tube on continuous suction is life‑saving.
• FETO improves survival but increases PPROM (47% vs 11%).
• Associated anomalies – cardiac (20%), chromosomal (10-15%), Beckwith-Wiedemann, Fryns.
• Neurodevelopmental issues common – especially with ECMO; must refer to early intervention.
📚 Key references: Nelson Textbook of Pediatrics 22e, TOTAL trial, CPSP guidelines.