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Congenital Diaphragmatic Hernia (CDH) — Paediatric Surgery

1. Definition & Overview

Congenital diaphragmatic hernia (CDH) is a spectrum of developmental anomalies marked by a defect in the diaphragm that allows abdominal contents to herniate into the thoracic cavity, disrupting lung and pulmonary vascular development. The spectrum ranges from a small posterior muscle-rim defect to complete diaphragmatic agenesis.
  • Incidence: ~1:2,000–5,000 live births (some studies cite 1:10,000–4:10,000)
  • Survival: 65%–90% at high-volume centres
  • 85% left-sided (Bochdalek), 13% right-sided, <2% bilateral/agenesis
  • 60% are isolated; if associated with other anomalies, mortality >85%
— Sabiston Textbook of Surgery, p. 2675; Creasy & Resnik's Maternal-Fetal Medicine, p. [CDH section]

2. Types of Diaphragmatic Hernia

TypeLocationFeatures
Bochdalek herniaPosterolateral (pleuroperitoneal canal)Most common; 85% left-sided; presents in neonatal period
Morgagni herniaAnterior (retrosternal / parasternal)Right-sided more common; often asymptomatic; delayed diagnosis into childhood
Central/agenesisCentral tendonRare; bilateral possible
Hiatal herniaOesophageal hiatusSliding or paraesophageal

3. Embryology & Pathophysiology

The diaphragm forms between weeks 4–12 of embryonic life from four components:
  1. Septum transversum
  2. Pleuroperitoneal folds
  3. Dorsal mesentery of oesophagus
  4. Lateral body wall
Failure of the pleuroperitoneal canal to close (usually the left side) creates the Bochdalek defect. Herniated abdominal viscera compress the developing lung, causing:
  • Pulmonary hypoplasia — bilateral; fewer airway branches, reduced lung compliance, abnormal pulmonary vasculature
  • Pulmonary hypertension — persistent fetal-type circulation; right-to-left shunting through PDA/PFO
  • Mediastinal shift — with contralateral lung compression
Associated anomalies (in 40% of cases):
  • Congenital heart disease (most common)
  • Chromosomal anomalies (trisomies 13, 18, 21)
  • Neural tube defects, urogenital anomalies

4. Prenatal Diagnosis & Assessment

Ultrasound Findings

  • Abdominal organs (bowel loops, stomach, liver) visualised in the chest
  • Cardiac deviation/mediastinal shift
  • Absence of normal diaphragmatic contour
  • Polyhydramnios (bowel obstruction)
  • Peristalsis of bowel in thorax
Left CDH: rightward heart shift + echolucent stomach/intestine in thorax Right CDH: harder to diagnose (liver similar to fetal lung echo); leftward heart shift; use Doppler of umbilical/hepatic veins + gallbladder position
Can be detected as early as 15 weeks gestation; 22–24 weeks standard.

Prognostic Tools

ToolDescriptionInterpretation
LHR (Lung-to-Head Ratio)Contralateral lung area ÷ head circumference<1.0 = poor prognosis; >1.4 = ~100% survival
O/E LHRObserved ÷ expected LHR for gestational ageO/E <25% → survival <20%
Liver herniationLiver "up" in chestIndependent predictor of worse outcome
Total fetal lung volume (MRI)Best quantification of lung volumeO/E TFLV <25–35% = severe
Diagnosis should prompt referral to a tertiary centre for advanced imaging, genetic testing (karyotype/microarray), fetal echocardiography, and multidisciplinary counselling.

5. Chest X-Ray (Classic Findings)

CDH CXR showing multiple gas-filled bowel loops in left hemithorax with mediastinal shift to the right, and right panel showing left diaphragmatic eventration with elevated hemidiaphragm
Figure: (A) CDH — multiple gas-filled bowel loops in left hemithorax; mediastinum shifted right. (B) Left diaphragmatic eventration — elevated hemidiaphragm (arrow) from phrenic nerve injury.
Classic CXR findings:
  • Multiple gas-filled bowel loops in hemithorax
  • Mediastinal shift to contralateral side
  • Scarcity of bowel gas in abdomen
  • Nasogastric tube coiling in thorax (if stomach herniated)
  • Absent left diaphragmatic shadow

6. Clinical Presentation

Neonatal (most common)

  • Respiratory distress at birth: grunting, dyspnea, retractions, cyanosis
  • Scaphoid abdomen (bowel contents in chest)
  • Diminished/absent breath sounds on affected side
  • Bowel sounds in chest
  • Displaced heart tones
  • Pre- and post-ductal SpO₂ difference (right-to-left shunting through PDA)

Delayed Presentation (10–20% after 24 hours; Morgagni more common)

  • Feeding difficulties
  • Recurrent chest infections / pneumonia
  • Respiratory distress triggered by respiratory illness
  • Occasionally, incidental finding on CXR

7. Fetal Intervention — FETO

Fetoscopic Endoluminal Tracheal Occlusion (FETO):
  • Tracheal balloon placed fetoscopically at 27–29 weeks gestation
  • Occludes trachea → retained lung fluid → lung growth stimulus
  • Balloon retrieved at ~34 weeks (or emergently if preterm labour)
TOTAL Trials (RCTs):
  • Severe CDH (O/E LHR <25%): FETO → 40% survival vs 15% expectant (trial stopped early for efficacy); benefit sustained at 6 months
  • Moderate CDH (O/E LHR 25–34.9%): No survival benefit shown at 30–34 weeks
Complications: Preterm labour, pPROM, preterm birth, fetal demise, tracheal stenosis
FETO is limited to specialist fetal therapy centres.

8. Postnatal Stabilisation — "Gentle Ventilation" Protocol

CDH repair is NOT a surgical emergency. Priority is cardiorespiratory stabilisation before surgery.

Airway & Ventilation

  • Avoid bag-mask ventilation (air swallowing worsens herniation)
  • Early intubation and nasogastric tube insertion for GI decompression
  • "Gentilation" / lung-protective strategy:
    • Peak inspiratory pressure (PIP) ≤25 cmH₂O
    • Permissive hypercapnia (PaCO₂ 45–65 mmHg, pH >7.2)
    • Pre-ductal SpO₂ target: 85–95%
    • Avoid high PEEP (worsens pulmonary hypertension)
  • High-frequency oscillatory ventilation (HFOV) if conventional fails

Pulmonary Hypertension Management

AgentMechanismNotes
Inhaled Nitric Oxide (iNO)Selective pulmonary vasodilatorFirst-line for iPPHN
SildenafilPDE-5 inhibitorOral/IV; combination with iNO
MilrinonePDE-3 inhibitor (inodilator)For RV dysfunction
PGE₁ / EpoprostenolProstanoidsSecond-line
BosentanEndothelin receptor antagonistEmerging role

ECMO (Extracorporeal Membrane Oxygenation)

Indicated when:
  • FiO₂ 1.0 + optimal ventilation → pre-ductal SpO₂ <85% or PaO₂ <40 mmHg
  • OI (Oxygenation Index) >40
  • Refractory pulmonary hypertension
VA-ECMO preferred for CDH (RV support). Repair can be performed on ECMO but carries higher bleeding risk.

9. Surgical Repair

Timing

  • Defer 48–72 hours after birth to allow haemodynamic stabilisation and reduce pulmonary vascular lability
  • On ECMO: timing controversial — some centres repair on ECMO; others wean first
  • Morgagni hernias: can be semi-elective

Approach

Open repair (standard):
  • Subcostal (transabdominal) incision — provides best access, allows bowel reduction and patch placement
  • Thoracotomy — used for thoracoscopic approach or Morgagni hernia
Minimally invasive (thoracoscopic / laparoscopic):
  • Increasingly used in stable infants >2.5 kg
  • Thoracoscopic approach most common for Bochdalek
  • Advantages: reduced trauma, faster recovery, better cosmesis
  • Concerns: hypercarbia and acidosis from CO₂ insufflation; higher recurrence rates in some series

Key Surgical Steps

  1. Reduction of herniated viscera into abdomen
  2. Assessment of diaphragmatic defect size
  3. Primary repair — if rim of posterior muscle present; non-absorbable sutures
  4. Patch repair — for large/absent rim
    • Synthetic: Gore-Tex (PTFE) — most common; risk of recurrence ~10–50% with large defects
    • Biological: porcine small intestinal submucosa (SIS), acellular dermal matrix
    • Muscle flaps: latissimus dorsi, serratus anterior — for recurrences or agenesis
  5. Avoid creating pneumothorax on ipsilateral side — do NOT drain unless tension
  6. Contralateral chest: assess for undrained pneumothorax

Primary vs Patch Repair

  • Small defect → primary closure (best outcomes, lowest recurrence)
  • Large/absent muscle rim → patch required (recurrence up to 50% with synthetic patch)
  • Patch recurrence presents with intestinal obstruction months–years later → requires re-exploration

10. Postoperative Management

  • Continue gentle ventilation; pulmonary hypertension may worsen post-op (inflammatory response)
  • Maintain iNO if pre-operatively required
  • Ipsilateral pleural drain is NOT routinely placed (lung re-expansion is gradual over days–weeks)
  • Early enteral feeding when tolerated
  • Monitor for intestinal obstruction (adhesions, recurrent hernia)

11. Complications & Long-Term Morbidity

ComplicationNotes
Recurrent hernia10–50%; higher with patch; may present with obstruction years later
Pulmonary hypertensionPersistent; requires ongoing sildenafil/bosentan in some
Bronchopulmonary dysplasiaChronic lung disease; oxygen dependence
GERD / OesophagitisVery common (>50%); often requires fundoplication
Feeding difficultiesDysphagia, poor weight gain; G-tube in ~30%
Neurodevelopmental delayEspecially in ECMO survivors
Chest wall deformitiesPectus excavatum/carinatum
ScoliosisLong-term surveillance required
Hearing lossEspecially after aminoglycosides/ECMO
Intestinal obstructionAdhesions or hernia recurrence

12. Diaphragmatic Eventration

Distinct from CDH — the diaphragm is intact but thinned/weakened (usually from phrenic nerve injury or congenital muscular weakness), causing paradoxical movement.
  • Acquired: phrenic nerve injury during cardiac/thoracic surgery
  • Congenital: true aplasia of diaphragmatic muscle fibres
Management: Diaphragmatic plication (thoracoscopic or open) — indicated for symptomatic cases with paradoxical movement and respiratory compromise. Especially in neonates who cannot wean from ventilation.

13. Summary Flowchart

Prenatal US diagnosis
        ↓
Tertiary referral → Echo + MRI + Genetics
        ↓
Severe (O/E LHR <25%)?
   YES → Consider FETO at 27–29 wks
   NO  → Expectant + planned delivery at tertiary centre
        ↓
Delivery → Immediate intubation + NGT
        ↓
Stabilise: Gentle ventilation, iNO, pulmonary vasodilators
        ↓
Refractory? → ECMO
        ↓
Stable 48–72 hrs → Surgical repair
(Primary closure if small defect; patch if large)
        ↓
Long-term follow-up: GI, pulmonary, neuro, hearing
Key Teaching Points for Exams:
  • CDH is a physiological emergency, not a surgical emergency — stabilise before operating
  • Left-sided (85%); Bochdalek (posterolateral) most common
  • Scaphoid abdomen + respiratory distress at birth = CDH until proven otherwise
  • LHR <1.0 = poor prognosis; FETO for severe CDH improves survival (TOTAL trial)
  • Permissive hypercapnia + avoid high PIP/PEEP = "gentilation"
  • iNO = first-line pulmonary vasodilator
  • Patch repair needed for large defects; recurrence is a major long-term problem
  • GERD and feeding difficulties are nearly universal survivors' morbidities
— Sabiston Textbook of Surgery, pp. 2675–2676; Creasy & Resnik's Maternal-Fetal Medicine (CDH chapter); Current Surgical Therapy 14e
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