Congenital diaphragmatic hernia is a developmental defect in the fetal diaphragm that allows abdominal viscera to herniate into the thoracic cavity, resulting in pulmonary hypoplasia and respiratory compromise at birth.

Congenital Diaphragmatic Hernia (CDH)

Congenital Diaphragmatic Hernia (CDH) is a developmental defect in the diaphragm that allows abdominal viscera to herniate into the thoracic cavity during fetal life, resulting in pulmonary hypoplasia and pulmonary hypertension. Breaking the name down:

"Congenital" = present from birth (Latin con- = together, genitus = born)
"Diaphragmatic" = pertaining to the diaphragm (Greek diaphragma = partition/barrier)
"Hernia" = protrusion of an organ through an abnormal opening (Latin hernia = rupture)

So the name tells you: a hernia through the diaphragm that is present at birth. The key consequence is not the hernia itself — it is the pulmonary hypoplasia (underdeveloped lungs) and persistent pulmonary hypertension of the newborn (PPHN) that develop because the herniated abdominal organs compress the developing lungs in utero, preventing normal lung growth.

The newborn baby cannot breathe: CDH is a surgical emergency where the primary pathology is pulmonary hypoplasia and pulmonary hypertension, not just the anatomical defect. ^[1]

Core Concept

CDH is fundamentally a lung disease with an anatomical cause. Fixing the hole in the diaphragm is necessary but insufficient — the baby must survive the pulmonary hypoplasia and pulmonary hypertension first. The operation is not the emergency; stabilization is.

2. Epidemiology

Parameter	Detail
Incidence	Approximately 1 in 2,500–3,500 live births ^[1]^[2]
Sex ratio	Slight male predominance (~1.5:1 M:F)
Side	Left-sided in ~80–85% of cases; right-sided in ~10–15%; bilateral in ~2% (almost always fatal) ^[1]^[2]
Associated anomalies	~40–50% have associated anomalies — cardiac anomalies (most common, ~20–30%), chromosomal (trisomy 13, 18, 21), neural tube defects, renal anomalies, skeletal anomalies ^[1]^[2]
Mortality	Despite advances, overall mortality remains ~20–40% in high-volume centres; significantly higher (>60%) in severe cases with liver herniation and low lung-to-head ratio ^[2]

The left pleuroperitoneal canal closes later than the right during embryological development (the right closes at ~6 weeks, the left at ~8 weeks of gestation). This longer window of vulnerability on the left means herniation is more likely on that side. Additionally, the liver provides a protective barrier on the right side, partially plugging the right pleuroperitoneal canal.

In Hong Kong, CDH is increasingly diagnosed antenatally via routine 18–22 week morphology ultrasound. Tertiary neonatal surgical centres (e.g., Queen Mary Hospital, Prince of Wales Hospital) manage these cases. The local incidence mirrors global figures. With the availability of ECMO and advanced neonatal ICU care in Hong Kong's tertiary centres, outcomes have improved, though severe CDH with liver herniation remains challenging.

3. Anatomy and Function of the Diaphragm

The diaphragm is a musculotendinous dome that separates the thoracic and abdominal cavities. It is the primary muscle of respiration.

Components:

Central tendon — the fibrous, non-contractile centre
Muscular portion — peripheral, arising from three origins:
- Sternal part — posterior surface of the xiphoid process
- Costal part — inner surfaces of the lower 6 ribs and their costal cartilages
- Lumbar (crural) part — the right and left crura from the lumbar vertebrae, the median and lateral arcuate ligaments

Openings:

Opening	Level	Contents
Caval hiatus	T8	IVC, right phrenic nerve
Oesophageal hiatus	T10	Oesophagus, vagus nerves
Aortic hiatus	T12	Aorta, thoracic duct, azygos vein

Blood supply: Phrenic arteries (inferior from the aorta, superior from the internal thoracic), musculophrenic and pericardiophrenic arteries.

Nerve supply: Phrenic nerve (C3, C4, C5) — "C3, 4, 5 keeps the diaphragm alive." This is motor to the diaphragm. Sensory to the central diaphragm is also phrenic; peripheral diaphragm sensation is from lower intercostal nerves.

The diaphragm forms from four embryological sources between weeks 4 and 8 of gestation:

Septum transversum — forms the central tendon (the largest contribution). Derived from mesoderm, initially at the cervical level (which is why the phrenic nerve originates from C3–C5: the nerve "follows" the diaphragm as it descends during development).
Pleuroperitoneal membranes — close the pleuroperitoneal canals (the communication between the thoracic and abdominal cavities). Failure of closure of the pleuroperitoneal canal → posterolateral (Bochdalek) hernia ^[1]^[2].
Dorsal mesentery of the oesophagus — forms the crura
Body wall mesoderm — muscular ingrowth from the lateral body wall

High Yield – Embryology

The posterolateral pleuroperitoneal canal is the last part of the diaphragm to close. The left closes later than the right. This is why Bochdalek hernias are left-sided in 80–85% of cases. ^[1]^[2]

Type	Eponym	Location	Frequency	Key Features
Posterolateral	Bochdalek	Posterolateral (pleuroperitoneal canal)	~80–90% of CDH	Most common; usually left-sided; associated with pulmonary hypoplasia ^[1]^[2]
Anterior/retrosternal	Morgagni	Sternocostal triangle (between sternal and costal origins)	~2–5% of CDH	Usually right-sided; often presents later in life; may contain omentum, transverse colon; less pulmonary hypoplasia ^[1]^[2]
Central	—	Central tendon	Rare	Associated with pentalogy of Cantrell
Eventration	—	Dome of diaphragm	Variable	Not a true hernia but a thinning/elevation of the diaphragm due to failure of muscular development; intact peritoneal covering

4. Etiology

CDH is predominantly sporadic (i.e., without a clear single genetic cause), though there is increasing recognition of genetic contributions:

Category	Details
Sporadic	Majority (~70–80%); no identifiable genetic or environmental cause
Chromosomal anomalies	Trisomy 13, 18, 21; Turner syndrome (45,X); Pallister-Killian syndrome (tetrasomy 12p — a classic association)
Single gene disorders	Mutations in genes regulating retinoid signalling (e.g., STRA6), Wnt signalling, ZFPM2/FOG2, GATA4, WT1
Syndromic	Fryns syndrome (autosomal recessive; CDH + distal limb hypoplasia + craniofacial anomalies), Cornelia de Lange syndrome, Donnai-Barrow syndrome
Environmental/teratogenic	Vitamin A deficiency (retinoid acid signalling is critical for diaphragm development — experimentally, nitrofen exposure in rodents disrupts retinoid signalling and causes CDH); thalidomide (historical); possibly mycophenolate exposure

The traditional "failure of closure" theory stated that the pleuroperitoneal membranes simply fail to fuse. However, modern understanding (the "retinoid hypothesis" and "dual-hit hypothesis") is more nuanced:

Primary defect: Abnormal development of the pleuroperitoneal folds, likely due to disrupted retinoid acid signalling in the post-hepatic mesenchymal plate (a transient mesodermal structure critical for diaphragm formation). This creates the diaphragmatic defect.
Secondary consequence: Once the defect exists, abdominal viscera herniate into the thorax. The mechanical compression of the ipsilateral lung (and to a lesser extent, the contralateral lung by mediastinal shift) during the critical canalicular and saccular stages of lung development (weeks 16–26) results in:
- Pulmonary hypoplasia — reduced bronchial branching, reduced alveolar number, thickened alveolar walls
- Pulmonary vascular hypoplasia — reduced number of pulmonary arterioles
- Abnormal pulmonary vascular remodelling — excessive muscularization of pulmonary arterioles (medial hypertrophy), extending into normally non-muscular intra-acinar vessels → this is the structural basis for persistent pulmonary hypertension of the newborn (PPHN)

The Dual-Hit Hypothesis

Modern research suggests the lung pathology in CDH is not solely due to mechanical compression. There may be a primary lung developmental defect (a "first hit") from the same disrupted signalling pathways (retinoid, Wnt) that caused the diaphragm defect, with mechanical compression acting as a "second hit." This explains why even the contralateral lung (which is not directly compressed) is also hypoplastic, and why some babies with relatively small defects still have severe pulmonary hypoplasia.

5. Pathophysiology

This is the crux of understanding CDH. Think of it as a cascade:

Both lungs are affected (ipsilateral > contralateral)
Reduced number of bronchial generations (normally 23; CDH may have 12–15)
Reduced total alveolar count → decreased gas exchange surface area
Thickened alveolar septa → impaired diffusion

Clinical consequence: The baby cannot adequately oxygenate or ventilate. The degree of pulmonary hypoplasia is the single most important determinant of survival.

Pulmonary arterioles are hypermuscularized — thick medial layer extends into normally thin-walled intra-acinar vessels
Reduced total cross-sectional area of the pulmonary vascular bed
High pulmonary vascular resistance (PVR) → prevents the normal postnatal drop in PVR that should occur when the baby takes its first breath

Why does PVR normally drop at birth? Because:

Lung inflation mechanically opens pulmonary vessels
Increased PaO₂ causes pulmonary vasodilation
Loss of placental circulation increases systemic vascular resistance (SVR)

In CDH, none of these mechanisms work properly:

Lungs are hypoplastic and poorly inflated
PaO₂ remains low due to poor gas exchange
The structurally abnormal vessels have a blunted response to vasodilators and an exaggerated response to vasoconstrictors (hypoxia, acidosis, hypercarbia)

Result: PVR remains high → right-to-left shunting through the patent ductus arteriosus (PDA) and patent foramen ovale (PFO) → deoxygenated blood bypasses the lungs and enters the systemic circulation → systemic cyanosis and hypoxemia

This creates a vicious cycle: hypoxia → acidosis → further pulmonary vasoconstriction → more right-to-left shunting → more hypoxia.

The herniated abdominal viscera push the mediastinum (heart + great vessels) to the contralateral side. This causes:

Compression of the contralateral lung (further reducing ventilatory capacity)
Kinking of the great vessels → impaired venous return → reduced cardiac output
Cardiac compression → reduced stroke volume

The abdominal cavity is under-developed (scaphoid abdomen) because the viscera have been in the thorax during development → the abdominal cavity is too small
This becomes relevant at the time of surgical repair: returning the viscera to a small abdominal cavity can cause abdominal compartment syndrome (increased intra-abdominal pressure → splinting of the diaphragm, compression of the IVC/renal vessels, respiratory compromise)

6. Classification

(See table in Section 3.3 — Bochdalek, Morgagni, central, eventration)

6.2. By Severity (for Prognostication)

Several classification systems exist to predict severity. The most commonly used:

Measured on antenatal ultrasound at 22–28 weeks:

O/E LHR > 45% → expected survival > 60% (moderate)
O/E LHR 25–45% → survival 15–60% (severe)
O/E LHR < 25% → survival < 15% (extreme)

Liver UP (herniated into thorax) → significantly worse prognosis ^[2]
Liver DOWN (remains in abdomen) → better prognosis

This is assessed on antenatal ultrasound or MRI.

Based on defect size at surgery:

A: Small defect with surrounding rim of diaphragm muscle
B: Defect involving < 50% of the hemidiaphragm
C: Defect involving > 50% of the hemidiaphragm
D: Complete agenesis of the hemidiaphragm

Type	Definition	Prognosis
Isolated CDH	CDH with no other major structural or chromosomal anomalies	Better prognosis
Complex CDH	CDH associated with other major anomalies (cardiac, chromosomal, syndromic)	Significantly worse prognosis

7. Clinical Features

In current practice, ~60–70% of CDH cases are diagnosed antenatally on routine morphology ultrasound (18–22 weeks) ^[1]^[2].

Ultrasound findings:

Polyhydramnios — due to compression/kinking of the oesophagus by herniated viscera, impairing fetal swallowing of amniotic fluid
Mediastinal shift — heart displaced to the contralateral side (in left CDH, the heart is pushed to the right)
Abdominal organs in the thorax — fluid-filled stomach/bowel loops visible above the diaphragm on the left; liver herniation on the right
Absent or poorly visualized stomach bubble in the abdomen (because the stomach is in the chest)
Small abdominal circumference — because less viscera in the abdomen
Pulmonary hypoplasia signs — small lung on the ipsilateral side

Antenatal MRI is increasingly used to:

Calculate total fetal lung volume (TFLV) — a better predictor of postnatal outcome than ultrasound LHR alone
Confirm liver position (UP vs DOWN)
Define the anatomy of herniated organs

Symptom	Pathophysiological Basis
Acute severe respiratory distress at birth	Pulmonary hypoplasia → inadequate gas exchange surface; PPHN → right-to-left shunting → systemic hypoxemia. The baby simply does not have enough functioning lung to sustain life ^[1]
Cyanosis (central — lips, tongue, mucous membranes)	Deoxygenated blood shunted right-to-left via PDA and PFO, bypassing the high-resistance pulmonary vasculature → mixing of deoxygenated blood into systemic circulation ^[1]
Tachypnoea	Compensatory attempt to increase minute ventilation in the face of reduced alveolar ventilation; peripheral/central chemoreceptor stimulation by hypoxia and hypercarbia
Grunting	Expiration against a partially closed glottis — an attempt to maintain positive end-expiratory pressure (PEEP) and prevent alveolar collapse in the hypoplastic lungs
Failure to cry or weak cry at birth	Inability to generate adequate respiratory effort due to severe pulmonary compromise
Feeding difficulties / vomiting (if presenting later)	Malrotation/volvulus of herniated bowel; gastric outlet obstruction from abnormal gastric position in the thorax

Timing of Presentation

Not all CDH presents immediately at birth. While severe CDH presents with acute respiratory distress within minutes of delivery, milder forms (especially right-sided with liver "plugging" part of the defect, or Morgagni hernias) may present days, weeks, or even months to years later with recurrent chest infections, feeding difficulties, or incidental CXR findings. Do not dismiss CDH just because the baby seemed fine initially. ^[1]^[2]

Sign	Pathophysiological Basis
Scaphoid (boat-shaped) abdomen	The abdominal cavity is underdeveloped and empty because the viscera are in the thorax. The anterior abdominal wall is concave rather than normally rounded. This is a classic and highly recognizable sign. ^[1]^[2]
Barrel-shaped chest (on the affected side)	Herniated viscera expand the hemithorax; the affected side may appear full and hyperexpanded
Absent or reduced breath sounds on the affected side	The lung on that side is hypoplastic and compressed; the hemithorax is filled with bowel/stomach/liver rather than aerated lung ^[1]
Bowel sounds audible in the chest	Peristaltic sounds from herniated bowel loops in the thoracic cavity — auscultate carefully and this can be heard
Displaced apex beat / heart sounds	Mediastinal shift pushes the heart to the contralateral side (in left CDH, the apex beat is shifted to the right) ^[1]
Cyanosis	As above — right-to-left shunting
Pre-ductal and post-ductal SpO₂ difference	Pre-ductal SpO₂ (right hand) > post-ductal SpO₂ (either foot) — a difference > 5–10% suggests significant right-to-left shunting through the PDA ^[1]. Pre-ductal blood comes from the left ventricle before the ductus arteriosus → relatively oxygenated. Post-ductal blood is mixed with deoxygenated blood shunting right-to-left through the PDA.
Signs of right heart failure (severe cases)	Hepatomegaly (but liver may already be in the chest), peripheral oedema — due to elevated right ventricular pressure from PPHN
Asymmetric chest movement	The affected side moves less with respiration (no functioning lung to expand); the contralateral side may show increased respiratory effort

A small proportion (~5–10%) present late:

Presentation	Mechanism
Recurrent chest infections / pneumonia	Herniated bowel or stomach acts as a space-occupying lesion; atelectasis of adjacent lung; possible aspiration
Chronic respiratory symptoms (cough, wheeze, dyspnoea)	Compression of functioning lung tissue
Intestinal obstruction / vomiting	Herniated bowel undergoes volvulus or incarceration in the thorax
Failure to thrive	Combination of respiratory compromise and feeding difficulties
Incidental CXR finding	Bowel gas pattern seen above the diaphragm on CXR performed for another reason

Morgagni hernias in particular tend to present late (even in adulthood) because they are anterior, smaller, and often contain only omentum or transverse colon, causing less pulmonary compression ^[1]^[2].

Clinical Feature	Why It Happens
Respiratory distress at birth	Pulmonary hypoplasia + PPHN → inadequate gas exchange
Cyanosis	Right-to-left shunting via PDA/PFO → deoxygenated blood in systemic circulation
Scaphoid abdomen	Abdominal viscera in thorax → empty, underdeveloped abdominal cavity
Absent breath sounds (ipsilateral)	Thorax filled with bowel, not aerated lung
Heart sounds shifted contralaterally	Mediastinal shift from mass effect of herniated viscera
Pre-post ductal SpO₂ gradient	Right-to-left ductal shunt; pre-ductal blood is from left ventricle (oxygenated), post-ductal includes shunted deoxygenated blood
Bowel sounds in chest	Peristalsis of herniated intestinal loops in the thoracic cavity
Deterioration with bag-mask ventilation	Air enters stomach/bowel in thorax → further distension → further lung compression → worsening respiratory failure

Critical Teaching Point

NEVER bag-mask ventilate a baby with suspected CDH. Bag-mask ventilation pushes air into the stomach and herniated bowel loops in the chest, causing them to distend further, compressing the already hypoplastic lung even more. Instead, intubate early and ventilate with an endotracheal tube (to direct air only into the lungs) and decompress the stomach with an orogastric/nasogastric tube on free drainage.*** ^[1]^[2]

This deserves special emphasis because associated anomalies significantly impact prognosis and management:

System	Anomalies	Frequency
Cardiovascular	VSD, ASD, coarctation of aorta, tetralogy of Fallot, hypoplastic left heart	~20–30% (most common associated anomaly) ^[1]^[2]
Chromosomal	Trisomy 13, 18, 21; Pallister-Killian syndrome (isochromosome 12p)	~10–15%
Genitourinary	Renal agenesis, horseshoe kidney, hydronephrosis, cryptorchidism	~15%
Musculoskeletal	Limb reduction defects, vertebral anomalies, rib abnormalities	Variable
Central nervous system	Neural tube defects, hydrocephalus	Variable
Gastrointestinal	Malrotation (almost universal in left CDH because the bowel herniates before completing normal rotation)	Very common

Malrotation in CDH

Malrotation is essentially universal in left-sided CDH because the midgut herniates into the thorax during the period when it should be rotating around the superior mesenteric artery and fixing to the posterior abdominal wall. When the bowel is returned to the abdomen during CDH repair, it will be malrotated. Most surgeons do NOT perform a formal Ladd procedure at the time of CDH repair (to avoid additional surgical stress on an already critically ill baby), but the malrotation must be documented and the family counselled. ^[2]

Concept	Detail
Most common type	Bochdalek (posterolateral), left-sided (~80%)
Fundamental pathology	Pulmonary hypoplasia + PPHN, NOT just the hole
Why left > right	Left pleuroperitoneal canal closes later; liver protects the right side
Why lungs are small	Mechanical compression by herniated viscera during canalicular/saccular phase of lung development; possibly primary lung developmental defect
Why PPHN	Muscularized pulmonary arterioles with blunted vasodilator response; reduced pulmonary vascular bed cross-section; hypoxic vasoconstriction
Classic triad at birth	Respiratory distress + cyanosis + scaphoid abdomen
Do NOT bag-mask ventilate	Air → stomach/bowel in chest → distension → worse compression

High Yield Summary

CDH = a defect in the diaphragm allowing abdominal viscera into the thorax, causing pulmonary hypoplasia and PPHN ^[1]^[2]
Bochdalek (posterolateral) hernia is the most common type (~80–90%), left-sided in ~80% ^[1]^[2]
Left > right because the left pleuroperitoneal canal closes later in embryological development ^[1]
Clinical triad: acute respiratory distress + cyanosis + scaphoid abdomen ^[1]
The severity depends on the degree of pulmonary hypoplasia — this is the main determinant of survival
PPHN creates a vicious cycle: hypoxia → vasoconstriction → R-to-L shunting → more hypoxia
Pre-ductal SpO₂ > post-ductal SpO₂ = evidence of right-to-left ductal shunting
NEVER bag-mask ventilate — intubate and insert NGT immediately ^[1]^[2]
~40–50% have associated anomalies; cardiac anomalies are the most common
Morgagni hernia (anterior) is rare and often presents late in life
Malrotation is essentially universal in left-sided CDH
Antenatal prognostic markers: O/E LHR, liver position (UP = worse), total fetal lung volume on MRI

Active Recall - Congenital Diaphragmatic Hernia (Definition, Epidemiology, Anatomy, Etiology, Pathophysiology, Clinical Features)

Differential Diagnosis of Congenital Diaphragmatic Hernia

The differential diagnosis of CDH is really about two clinical scenarios:

The antenatal scenario: An ultrasound shows what looks like abdominal contents in the fetal thorax — what else could this be?
The postnatal scenario: A newborn presents with acute respiratory distress, cyanosis, and/or a scaphoid abdomen — what else could cause this picture?

The DDx differs depending on which scenario you are faced with. Let us work through both systematically.

Think about the DDx in three buckets:

Conditions that mimic CDH on antenatal imaging (intrathoracic masses / abnormal diaphragm)
Conditions that cause acute neonatal respiratory distress (the presenting complaint of CDH)
Conditions that cause a scaphoid abdomen in the newborn (the classic sign)

B. Detailed Differential Diagnosis

Condition	What It Is	How to Distinguish from CDH
Congenital Pulmonary Airway Malformation (CPAM / CCAM)	Hamartomatous malformation of the lung with abnormal cystic or adenomatoid tissue replacing normal lung parenchyma. Previously called "congenital cystic adenomatoid malformation."	On USS: the mass is within the lung parenchyma (not from the abdomen). No herniated abdominal viscera. The stomach bubble remains in the abdomen. On MRI: no bowel loops in the chest; lung tissue signal, not bowel. Postnatally on CXR: air-filled cysts within the lung rather than bowel gas pattern ^[1]^[3]
Bronchopulmonary Sequestration (BPS)	A mass of non-functioning lung tissue that has no connection with the tracheobronchial tree and receives its blood supply from an anomalous systemic artery (usually from the aorta). Intralobar (within visceral pleura) or extralobar (own pleural covering).	On USS: a solid echogenic mass, usually left lower lobe. Key distinguishing feature is identifying an aberrant systemic arterial feeding vessel from the aorta on colour Doppler. No peristalsis. No stomach in the chest. Postnatally: does not contain bowel gas
Bronchogenic Cyst	A congenital cyst arising from abnormal budding of the ventral foregut/tracheobronchial tree, lined by respiratory epithelium.	Usually mediastinal or perihilar, solitary. On USS: well-defined anechoic cyst. Does not contain bowel loops. Postnatally: a single round opacity, often incidental finding
Congenital Lobar Overinflation (CLO, formerly Congenital Lobar Emphysema)	Progressive hyperinflation of one or more lobes due to a "ball-valve" mechanism (intrinsic cartilage deficiency, extrinsic compression, or idiopathic).	Postnatally: the affected lobe is hyperinflated and hyperlucent on CXR, with mediastinal shift — but there are NO bowel loops in the chest. The key difference is the uniform hyperlucency of the affected hemithorax vs. the mixed density (bowel gas + soft tissue) in CDH
Eventration of the Diaphragm	Elevation of part or all of a hemidiaphragm due to failure of muscular development — the diaphragm is present but thin and floppy (attenuated). There is an intact peritoneal/pleural membrane (unlike CDH where there is a true defect).	On CXR: the diaphragm is elevated but you can still identify a smooth diaphragmatic contour. Abdominal organs are pushed up but remain below a visible diaphragmatic line. In CDH, there is no visible diaphragmatic line on the affected side — bowel loops are freely within the thorax. Functionally, eventration can also cause respiratory compromise but is usually less severe than CDH because there is no true pulmonary hypoplasia (the lungs developed with the diaphragm present, just thin)

CPAM vs CDH on CXR — A Common Exam Pitfall

Both CPAM (especially Type 1, macrocystic) and left-sided CDH can show cystic/lucent spaces in the left hemithorax with mediastinal shift on neonatal CXR. The critical distinguishing features are:

CDH: Bowel gas pattern (irregular, multiple, with visible haustra or valvulae conniventes), NGT tip in the thorax (because the stomach is herniated), scaphoid abdomen, absent gas in the abdomen on AXR
CPAM: Round, smooth-walled cysts, gas distributed normally in the abdomen, NGT in the abdomen, no scaphoid abdomen

This is the more common exam scenario: a newborn in the delivery room with respiratory distress. You need to differentiate CDH from other causes.

Condition	Pathophysiology	Key Distinguishing Features
Respiratory Distress Syndrome (RDS / Hyaline Membrane Disease)	Surfactant deficiency → alveolar collapse → diffuse atelectasis. Almost exclusively premature neonates ( < 37 weeks, especially < 34 weeks).	Bilateral symmetric ground-glass opacification with air bronchograms on CXR ^[6]. Low lung volumes. Normal abdominal contour (not scaphoid). Risk factors: prematurity, male sex, maternal diabetes. Responds to surfactant therapy.
Meconium Aspiration Syndrome (MAS)	Meconium-stained amniotic fluid is aspirated → chemical pneumonitis, airway obstruction, surfactant inactivation. Term or post-term infants with perinatal distress.	History of meconium-stained liquor. CXR: bilateral coarse, patchy, asymmetric opacities; hyperinflation; possible pneumothorax. The abdomen is not scaphoid.
Transient Tachypnoea of the Newborn (TTN)	Delayed resorption of fetal lung fluid, classically after elective Caesarean section (because labour squeezes fluid out of the lungs — no labour means more retained fluid).	Mild respiratory distress, resolves within 24–72 hours. CXR: perihilar streaky opacities, fluid in the fissures, mild cardiomegaly. Self-limiting.
Neonatal Pneumonia	Ascending infection (GBS, E. coli) or transplacental infection.	Maternal risk factors: prolonged rupture of membranes, GBS colonization, chorioamnionitis, maternal fever. CXR may mimic RDS (bilateral opacities) or show lobar consolidation. Septic screen positive.
Pneumothorax	Air leak into pleural space, may be spontaneous or iatrogenic (e.g., vigorous resuscitation).	Sudden deterioration. CXR: hyperlucent hemithorax with absent lung markings, visible lung edge, mediastinal shift to contralateral side. But unlike CDH: no bowel loops in the chest, abdomen is not scaphoid, and you can see the collapsed lung edge.
Persistent Pulmonary Hypertension of the Newborn (PPHN) — idiopathic or secondary	Same PPHN physiology as in CDH, but without a diaphragmatic defect. Can be primary (idiopathic), or secondary to MAS, RDS, sepsis, perinatal asphyxia.	CXR may be relatively normal or show the underlying cause (MAS/RDS/pneumonia). ^[6] Pre/post-ductal SpO₂ gradient present. Echocardiogram shows R-to-L shunting via PDA/PFO but structurally normal heart and intact diaphragm.
Cyanotic Congenital Heart Disease (e.g., Transposition of Great Arteries, Total Anomalous Pulmonary Venous Return, Tetralogy of Fallot)	Structural cardiac lesion causing deoxygenated blood to enter systemic circulation.	CXR: may show oligaemic lung fields (reduced pulmonary blood flow) in certain lesions. ^[7] Does NOT respond to 100% oxygen ("failed hyperoxia test"). Echocardiography is diagnostic. No scaphoid abdomen. Breath sounds bilaterally present. As per AOS past paper: "radiograph showing an oligaemic lung field due to reduced pulmonary blood flow" supports cyanotic CHD over respiratory disease as the cause of cyanosis ^[7]
Oesophageal Atresia with Tracheo-Oesophageal Fistula (OA/TOF)	Blind-ending upper oesophageal pouch (unable to swallow saliva/feeds) ± fistula between trachea and lower oesophagus → aspiration.	Excessive drooling/frothing, choking/cyanosis with feeds. Cannot pass NGT (coils in the upper pouch on CXR). If distal TOF present, air enters the stomach/bowel → gaseous distension of abdomen (not scaphoid). The respiratory distress is secondary to aspiration, not primary pulmonary hypoplasia. ^[1]

On GC lecture slides: "Herniated abdominal contents prevent lung growth" — this is the fundamental distinction between CDH and almost all other causes of neonatal respiratory distress. In CDH, the lung is structurally underdeveloped (hypoplastic), whereas in RDS, MAS, pneumonia, etc., the lungs are structurally normal but functionally impaired. ^[1]^[8]

The scaphoid abdomen is a very specific clue. Very few conditions cause it:

Condition	Why Scaphoid?
CDH	Abdominal viscera herniated into thorax → empty abdominal cavity
Oesophageal Atresia WITHOUT distal fistula (pure OA)	No air can enter the GI tract (no fistula connecting trachea to distal oesophagus) → gasless abdomen → scaphoid appearance. But this is a gasless abdomen rather than a true loss of viscera from the abdomen. In OA with distal TOF (the most common type, ~85%), air passes through the fistula into the stomach, so the abdomen is NOT scaphoid. ^[1]
High intestinal atresia (e.g., duodenal atresia) without distal air	Very rare scenario; usually some gas is present in the proximal bowel

High Yield Exam Point

If you see a newborn with respiratory distress + scaphoid abdomen + absent breath sounds on one side + displaced heart sounds → CDH until proven otherwise. The combination of scaphoid abdomen with unilateral absent breath sounds is virtually pathognomonic. ^[1]^[3]^[6]

Feature	CDH	CPAM	Pneumothorax	RDS	Cyanotic CHD	OA/TOF
Gestation	Any	Any	Any	Premature	Any	Any
Scaphoid abdomen	Yes	No	No	No	No	Only if pure OA
Bowel sounds in chest	Yes	No	No	No	No	No
CXR: bowel loops in thorax	Yes	No (cysts only)	No	No	No	No
CXR: mediastinal shift	Yes	Possible	Yes	No	Variable	No
Abdomen on CXR	Gasless / few loops	Normal gas pattern	Normal	Normal	Normal	Gasless if pure OA
Hyperoxia test	May partially respond	Responds	Responds	Responds	Fails	Responds
Echocardiogram	PPHN, structural heart normal (unless associated CHD)	Normal	Normal	Normal	Structural lesion	Normal
NGT position	May coil in thorax (stomach in chest)	In abdomen	In abdomen	In abdomen	In abdomen	Coils in upper pouch

For late-presenting CDH (beyond the neonatal period), the differential is different because the presentation is chronic or subacute:

DDx for Late CDH	Rationale
Recurrent pneumonia / bronchiectasis	CDH with partial herniation can cause recurrent lower lobe infections
Empyema / parapneumonic effusion	Opacification of hemithorax on CXR
Pleural effusion (any cause)	Opacification with mediastinal shift
Diaphragmatic eventration	Elevated hemidiaphragm with abdominal organs pushed up
Acquired (traumatic) diaphragmatic hernia	Post-trauma — but in children, think about non-accidental injury
Morgagni hernia presenting incidentally	Anterior retrosternal hernia, usually containing omentum/transverse colon, often right-sided, may present as incidental CXR finding ^[1]^[8]
Mediastinal tumour (e.g., neuroblastoma, lymphoma)	Space-occupying lesion in the thorax

GC lecture slide: "Prenatal diagnosis — worse prognosis with earlier diagnosis" — this means CDH detected early (before 25 weeks) tends to be more severe because the defect was large enough and the herniation extensive enough to be visible early. This does NOT mean that prenatal diagnosis itself worsens outcomes — it is a marker of severity, not a cause of worsened outcome. ^[8]

Investigation	What It Tells You
CXR (first-line, immediate)	Bowel loops in thorax = CDH. Air-filled cysts = CPAM. Absent lung markings with visible lung edge = pneumothorax. Bilateral ground-glass = RDS.
NGT position on CXR	NGT tip in thorax = stomach herniated (CDH). NGT coiled in upper pouch = OA.
Echocardiography	Rules out structural CHD. Assesses PPHN severity (pulmonary artery pressure, R-to-L shunting). Essential for ALL neonates with cyanosis.
Hyperoxia test	PaO₂ rises to > 150 mmHg in lung disease (including CDH). PaO₂ fails to rise in cyanotic CHD.
Abdominal radiograph	Gasless abdomen supports CDH (viscera in thorax). Normal bowel gas pattern argues against CDH.

If you are considering...	Rule it out because...
CPAM	No bowel in thorax, stomach in abdomen, no scaphoid abdomen
Pneumothorax	Can see collapsed lung edge, no bowel pattern, no scaphoid abdomen
RDS	Bilateral symmetric, premature, no scaphoid abdomen, no unilateral absent breath sounds
Cyanotic CHD	Fails hyperoxia test, echocardiography shows structural lesion, breath sounds present bilaterally
OA/TOF	NGT coils in upper pouch, drooling/frothing, abdomen NOT scaphoid (if distal fistula present)
Eventration	Smooth diaphragmatic contour visible on CXR, usually less severe, no true bowel in the chest

High Yield Summary — Differential Diagnosis of CDH

The classic triad (respiratory distress + cyanosis + scaphoid abdomen) with absent breath sounds and bowel sounds in the chest is virtually pathognomonic for CDH
CPAM is the most important antenatal mimic — differentiate by confirming the mass is pulmonary tissue, not bowel (no peristalsis, stomach in abdomen)
Pneumothorax is the most important postnatal mimic — differentiate by visible collapsed lung edge on CXR, no bowel gas pattern in thorax
CXR is the key discriminating investigation — bowel loops above the diaphragm with mediastinal shift + gasless/paucity of gas in the abdomen = CDH
For cyanotic CHD, use the hyperoxia test and echocardiography — CDH will partially respond to O₂, CHD will not
NGT position on CXR helps differentiate CDH (tip in thorax) from OA (coiled in upper pouch)
GC slide: "Worse prognosis with earlier diagnosis" refers to severity (larger defects detected earlier), not a causal effect of prenatal diagnosis itself ^[8]
Malrotation is essentially universal in left CDH — always consider midgut volvulus as a concurrent or future surgical concern ^[3]^[5]

Active Recall - Differential Diagnosis of CDH

References

^[1] Lecture slides: GC 204. The newborn baby cannot breathe Oesophageal atresia, diaphragmatic hernia, and other surgery of lung.pdf ^[2] Lecture slides: Neonatal Surgery.pdf ^[3] Senior notes: Maksim Surgery Notes.pdf (p333) ^[4] Senior notes: Adrian Lui Pediatrics Notes.pdf (p57) ^[5] Senior notes: MBBS Final MB (Pediatrics) (Felix PY Lai).pdf (p357) ^[6] Senior notes: Maksim Paediatric Notes.pdf (p69) ^[7] AOS material: AOS - Paeds.pdf (Question 6 — oligaemic lung fields supporting cyanotic CHD) ^[8] Lecture slides: GC 205. The newborn baby is vomiting repeatedly Neonatal intestinal obstruction and other GI emergencies.pdf (p31)

Diagnosis of Congenital Diaphragmatic Hernia

CDH does not have formal "diagnostic criteria" in the way that, say, rheumatoid arthritis has the ACR/EULAR criteria. Instead, the diagnosis is made by combining clinical features with imaging findings. The diagnosis is straightforward when you see the right constellation:

Antenatal diagnosis requires:

Ultrasound or MRI demonstrating abdominal viscera within the fetal thorax, with or without mediastinal shift, and an identifiable diaphragmatic defect

Postnatal diagnosis requires:

Clinical features consistent with CDH (respiratory distress, cyanosis, scaphoid abdomen, absent breath sounds on the affected side) PLUS
CXR/AXR confirming bowel loops in the ipsilateral thorax, mediastinal shift, and paucity of bowel gas in the abdomen ^[3]^[4]

The diagnosis is essentially clinical + radiological. There is no blood test, no biomarker, no scoring system. If you see bowel in the chest on imaging in a neonate with respiratory distress and a scaphoid abdomen, you have the diagnosis.

Definitive confirmation occurs at the time of surgical repair, where the diaphragmatic defect is directly visualised and the herniated contents are identified and reduced.

B. Diagnostic Algorithm

The algorithm differs based on when the diagnosis is made — antenatally vs postnatally.

C. Investigation Modalities — Detailed

C1. Antenatal Investigations

This is the primary screening and diagnostic tool. Most CDH cases are now diagnosed antenatally on routine morphology ultrasound. ^[4]^[8]

Finding	Interpretation	Why It Happens
Abdominal organs above the diaphragm (stomach bubble, bowel loops, liver in the thorax)	Confirms herniation. Left CDH: stomach, spleen, intestines, ± left lobe of liver. Right CDH: liver, intestines.	The diaphragmatic defect allows viscera to pass from abdomen to thorax
Mediastinal shift	Heart displaced contralaterally. In left CDH → heart pushed to the right.	Mass effect of herniated organs
Polyhydramnios	Excessive amniotic fluid around the fetus	Herniated stomach/oesophageal compression impairs fetal swallowing of amniotic fluid
Small or absent stomach bubble in the abdomen	The stomach has herniated into the chest	Stomach is no longer in its normal subdiaphragmatic position
Small abdominal circumference	Fewer organs in the abdomen	Viscera have migrated into the thorax

Prognostic markers on USS:

Marker	How It Is Measured	Prognostic Significance
Lung-to-Head Ratio (LHR)	Area of contralateral lung (at the level of the 4-chamber cardiac view) ÷ head circumference	Raw LHR varies with gestational age, so the observed-to-expected (O/E) LHR is preferred
O/E LHR	Measured LHR as a percentage of the expected LHR for that gestational age (using reference charts, best measured at 22–28 weeks)	O/E LHR > 45% → survival > 60%. O/E LHR 25-45% → survival 15-60%. O/E LHR < 25% → survival < 15%.
Liver position	Identify whether the liver is above (UP) or below (DOWN) the diaphragm	Liver UP = significantly worse prognosis (larger defect, more herniation, greater pulmonary compression)
Stomach position	Is the stomach intrathoracic?	Intrathoracic stomach implies a large defect

GC slide: "Prenatal diagnosis (worse prognosis with earlier diagnosis)" — CDH detected earlier in gestation implies a larger defect detectable at an earlier stage, hence more severe pulmonary hypoplasia. This is a severity marker, not a causal relationship. ^[8]

Aspect	Detail
When	Typically performed at 28–32 weeks after USS suggests CDH
Why	Superior soft tissue contrast compared to USS; better for calculating total fetal lung volume (TFLV); better at defining liver position (UP vs DOWN); identifies associated anomalies
Key measurements	Total fetal lung volume (TFLV) — correlates with degree of pulmonary hypoplasia. O/E TFLV < 25% = severe hypoplasia. Liver herniation volume can also be quantified.
Advantages over USS	Less operator-dependent; more accurate lung volumetry; better visualization in late gestation when USS quality declines due to fetal size/position
Safety	No ionising radiation; safe for the fetus. Gadolinium contrast is generally avoided in pregnancy

Aspect	Detail
Why	~10–15% of CDH cases are associated with chromosomal anomalies (trisomy 13, 18, 21; Pallister-Killian syndrome). Identifying aneuploidy changes prognosis and may alter management (e.g., trisomy 18 is often considered incompatible with long-term survival, affecting counselling)
How	Amniocentesis at 15–20 weeks → karyotype, chromosomal microarray, or FISH for rapid aneuploidy screening
When indicated	All antenatally diagnosed CDH cases should be offered genetic testing

Aspect	Detail
Why	Cardiac anomalies are the most common associated anomalies (~20–30%) — e.g., VSD, ASD, coarctation, TOF, HLHS
When	At the time of CDH diagnosis or shortly after
Impact	Associated major cardiac anomaly significantly worsens prognosis and may alter management decisions (e.g., suitability for ECMO, surgical planning)

Antenatal Workup Summary

Every antenatally diagnosed CDH needs: (1) Detailed USS with O/E LHR + liver position, (2) Fetal MRI for lung volumetry, (3) Amniocentesis/karyotype/microarray, (4) Fetal echocardiography. This package allows comprehensive prognostication and counselling.

C2. Postnatal Investigations

This is the single most important postnatal investigation — it confirms the diagnosis in the vast majority of cases.

CXR/AXR findings in CDH: ^[3]^[4]^[6]

Finding	Interpretation	Pathophysiological Basis
Bowel loops in the ipsilateral thorax	The hallmark finding. Irregular air-filled lucencies with a bowel gas pattern (haustra, valvulae conniventes) above the expected diaphragm level	Herniated intestines containing swallowed air
Mediastinal shift to the contralateral side	Heart shadow, trachea, and mediastinal structures displaced away from the affected side	Mass effect of herniated viscera pushing the mediastinum
Contralateral lung collapse/compression	Opacification or reduced aeration of the contralateral lung	Mediastinal shift compresses the contralateral lung
Loss of the hemidiaphragm silhouette on the affected side	Cannot identify the normal smooth dome of the diaphragm	The diaphragm is absent or has a large defect — no structure to cast a silhouette
Paucity of bowel gas in the abdomen	Very few or no gas-filled loops below the diaphragm	Most of the bowel is in the thorax, not the abdomen
NGT tip in the thorax	If an NGT has been placed, it may be seen curling up into the thorax rather than descending to the abdomen	The stomach is herniated into the chest; the NGT follows the stomach

Senior note: "CXR: bowel loops in ipsilateral thorax, mediastinal shift, contralateral lung collapse" ^[3]

Additional lines/tubes to identify on the CXR:

Endotracheal tube (ETT) position — tip should be 1–2 cm above the carina
Nasogastric tube — follow its course; if it goes into the thorax, the stomach is herniated
Umbilical arterial catheter (UAC) — courses inferiorly via the umbilical artery to the aorta, then ascends (tip at T6–T9 or L3–L4)
Umbilical venous catheter (UVC) — courses superiorly via the umbilical vein to the IVC/right atrium (tip at the diaphragm/right atrium junction)

These lines help confirm the baby is intubated (not bag-masked), has gastric decompression, and has vascular access. ^[6]

CXR Interpretation Pitfall

In the first few hours of life, the herniated bowel may not yet contain enough swallowed air to show a typical bowel gas pattern. The CXR may show a homogeneous opacification of the affected hemithorax (fluid-filled bowel without gas) that can mimic a pleural effusion, lobar consolidation, or CPAM. If clinical suspicion is high, repeat CXR after a few hours (as the baby swallows air and the bowel becomes gas-filled) or proceed to further imaging.

Measurement	Site	Normal	CDH with PPHN
Pre-ductal SpO₂	Right hand (because the right subclavian artery arises from the brachiocephalic trunk, which branches off the aorta proximal to the ductus arteriosus)	> 95%	Reduced, but higher than post-ductal
Post-ductal SpO₂	Either foot (lower extremity arteries arise from the aorta distal to the ductus arteriosus)	> 95%	Lower than pre-ductal
Gradient	Pre-ductal minus post-ductal	< 3% difference	> 5-10% difference indicates significant R-to-L ductal shunting ^[4]

Why the right hand for pre-ductal? The left subclavian artery origin is variable — in some individuals, it arises at or near the ductus arteriosus, making the left hand unreliable for pre-ductal measurement. The right hand is always pre-ductal because the right subclavian arises from the brachiocephalic trunk, which is the first branch of the aortic arch.

Senior note: "Oximetry: > 10% difference between preductal vs post-ductal saturation (R thumb vs great toe) due to R-to-L shunt via PDA, but absence does not r/o PPHN as shunting can occur via PFO" ^[4]

Important Nuance

If the shunting is predominantly through the PFO (patent foramen ovale) rather than the PDA, deoxygenated blood enters the left atrium and mixes with oxygenated blood before being ejected into the aorta proximal to the ductus. In this scenario, both pre-ductal and post-ductal SpO₂ will be low, with no significant gradient. Therefore, the absence of a pre-post ductal gradient does NOT rule out PPHN — it just means the shunt is at the atrial level rather than the ductal level. ^[4]

Parameter	Expected Finding in CDH	Interpretation
PaO₂	Low (hypoxemia)	Pulmonary hypoplasia → inadequate gas exchange; R-to-L shunting → deoxygenated blood in systemic circulation
PaCO₂	High (hypercarbia)	Reduced alveolar ventilation due to pulmonary hypoplasia
pH	Low (acidosis) — mixed respiratory and metabolic	Respiratory acidosis from CO₂ retention + metabolic acidosis from tissue hypoxia (lactic acidosis)
Lactate	Elevated	Tissue hypoperfusion and anaerobic metabolism
Base excess	Negative (base deficit)	Metabolic acidosis component

Key point for differentiating from cyanotic CHD:

Senior note: "ABG: low PaO₂ despite 100% O₂ (similar to cyanotic CHD) — should have at least 1 measurement of PaO₂ > 100 mmHg early on (cf NEVER high PaO₂ in cyanotic CHD)" ^[4]

This is a critical distinguishing feature. In CDH/PPHN, if you catch the baby early or during a transient improvement, PaO₂ may briefly rise above 100 mmHg on 100% O₂ — because the lungs are hypoplastic but not absent, and some alveoli can still function. In cyanotic CHD with a fixed R-to-L shunt (e.g., TGA), PaO₂ never reaches > 100 mmHg regardless of FiO₂ because the shunt is anatomically fixed. This is the basis of the hyperoxia test.

Purpose	What You're Looking For	Why It Matters
Assess PPHN severity	Estimated pulmonary artery pressure (using tricuspid regurgitant jet velocity via the modified Bernoulli equation: ΔP = 4v²); direction of shunting at PDA and PFO (R-to-L = PPHN); right ventricular dilation and dysfunction; septal bowing towards the LV	Guides the intensity of pulmonary vasodilator therapy (iNO, sildenafil) and the decision to escalate to ECMO
Rule out associated structural CHD	VSD, ASD, coarctation of aorta, TOF, HLHS, etc.	~20–30% of CDH have associated cardiac anomalies — these affect surgical planning, ECMO candidacy, and overall prognosis
Assess cardiac function	LV and RV systolic function; cardiac output	RV failure from PPHN can cause systemic hypotension
Confirm normal structural anatomy (if idiopathic PPHN is in the DDx)		If the heart is structurally normal AND PPHN is present, confirms the PPHN is secondary to CDH rather than a primary cardiac lesion

Echocardiography must be performed in every neonate with CDH — it is the definitive investigation for PPHN assessment and exclusion of associated CHD. ^[3]^[4]

Test	Purpose
Full blood count (CBC)	Baseline haemoglobin (for transfusion planning); WCC (infection); platelets (may drop with ECMO or DIC)
Coagulation profile (PT, APTT, fibrinogen)	Baseline for surgical planning; DIC screening (sick neonates can develop DIC)
Blood group + crossmatch	Surgical repair anticipated; ECMO requires primed circuit with blood products
Electrolytes, renal function, glucose	Baseline metabolic assessment; hypoglycaemia is common in sick neonates; assess renal perfusion
Blood culture	Rule out concomitant neonatal sepsis (which can mimic or exacerbate PPHN)
Lactate	Marker of tissue perfusion — rising lactate indicates worsening shock
Chromosomal analysis / microarray	If not done antenatally — to rule out associated chromosomal anomalies

Investigation	When	What It Shows
CT thorax/abdomen	Rarely needed in acute neonatal CDH; may be used in late-presenting or atypical CDH (e.g., Morgagni hernia presenting in older child/adult)	Precisely delineates the defect, herniated contents, and lung volume. Can differentiate from CPAM, sequestration, or eventration
Upper GI contrast study	Late-presenting CDH with unclear CXR; or post-repair to assess for malrotation	Shows bowel position; can confirm intrathoracic bowel if CXR is equivocal
Cranial ultrasound	Baseline in all sick neonates, especially if ECMO is considered	Rule out intracranial haemorrhage (ICH is a contraindication to ECMO due to systemic heparinization)
Renal ultrasound	Part of the screen for associated anomalies	~15% have renal anomalies (agenesis, horseshoe kidney, hydronephrosis)

Senior note on diaphragmatic hernia on CXR: widened mediastinum DDx includes "diaphragmatic hernia" — in the context of adult medicine, a widened mediastinum on CXR can be caused by a diaphragmatic hernia (particularly if stomach or bowel herniates through and creates mass effect). This is more relevant for traumatic diaphragmatic rupture in adults but the radiological principle is the same. ^[9]^[10]

After the diagnosis is confirmed, the investigations are used to stratify severity and plan management:

Prognostic Factor	Good Prognosis	Poor Prognosis
O/E LHR	> 45%	< 25%
Liver position	DOWN (in abdomen)	UP (in thorax)
TFLV on MRI	O/E TFLV > 35%	O/E TFLV < 15%
Side of defect	Right-sided (less severe pulmonary hypoplasia due to liver protection)	Left-sided severe or bilateral
Associated anomalies	Isolated CDH	Complex CDH with major cardiac/chromosomal anomalies
Postnatal: best PaO₂ in first 24h	PaO₂ > 100 mmHg achievable	PaO₂ never > 100 mmHg
Postnatal: oxygenation index (OI)	OI < 25	OI > 40 — consider ECMO
Postnatal: pre-ductal SpO₂	Maintained > 85% pre-ductal	Persistently < 80% pre-ductal despite maximal therapy

Oxygenation Index (OI) is calculated as:

OI = (FiO₂ × Mean Airway Pressure × 100) / PaO₂

An OI > 25 is concerning; OI > 40 despite maximal medical therapy is a widely used threshold for ECMO referral.

Phase	Key Investigation	Key Finding
Antenatal screening	Morphology USS (18–22 wk)	Abdominal organs in thorax, mediastinal shift, polyhydramnios
Antenatal prognostication	O/E LHR, liver position, fetal MRI (TFLV), karyotype, fetal echo	Predicts severity and guides delivery planning
Immediate postnatal	CXR + AXR	Bowel loops in thorax, mediastinal shift, paucity of abdominal gas, loss of hemidiaphragm, NGT tip in thorax ^[3]^[6]
Postnatal — assess PPHN	Pre/post-ductal SpO₂, ABG, echocardiography	SpO₂ gradient > 5–10%, low PaO₂, echo shows R-to-L shunt and elevated PAP
Postnatal — exclude associations	Echocardiography, renal USS, karyotype	Cardiac anomalies, renal anomalies, chromosomal anomalies
Postnatal — guide therapy	ABG (serial), lactate, OI calculation	Track response to treatment; OI > 40 → ECMO

High Yield Summary — Diagnosis of CDH

Antenatal USS is the primary diagnostic tool — most CDH is now diagnosed before birth ^[4]^[8]
CXR is the first-line postnatal investigation — bowel loops in thorax + mediastinal shift + gasless abdomen = CDH ^[3]^[6]
NGT tip in the thorax on CXR means the stomach is herniated — virtually confirms CDH
Pre-ductal SpO₂ (right hand) > post-ductal SpO₂ (foot) with > 5–10% gradient = significant R-to-L ductal shunting ^[4]
Absence of pre-post ductal gradient does NOT rule out PPHN — shunting may be via PFO instead of PDA ^[4]
Echocardiography is essential in every CDH case — to assess PPHN severity AND rule out associated structural CHD
ABG: PaO₂ should reach > 100 mmHg at least once early on — if PaO₂ NEVER rises above 100 on 100% O₂, suspect cyanotic CHD instead ^[4]
Prognostic markers: O/E LHR, liver position, TFLV on MRI, associated anomalies, best PaO₂ in first 24h, OI
OI > 40 on maximal medical therapy → consider ECMO referral
All CDH neonates need karyotype/microarray + fetal/neonatal echocardiography + renal USS to screen for associated anomalies

Active Recall - Diagnosis and Investigations of CDH

References

^[1] Lecture slides: GC 204. The newborn baby cannot breathe Oesophageal atresia, diaphragmatic hernia, and other surgery of lung.pdf ^[3] Senior notes: Maksim Surgery Notes.pdf (p333) ^[4] Senior notes: Adrian Lui Pediatrics Notes.pdf (p54) ^[6] Senior notes: Maksim Paediatric Notes.pdf (p69) ^[8] Lecture slides: GC 205. The newborn baby is vomiting repeatedly Neonatal intestinal obstruction and other GI emergencies.pdf (p31) ^[9] Senior notes: Block A - Introduction to CVS investigations (including ECG).pdf (p8) ^[10] Lecture slides: General Clerkship Introduction to CVS Investigations 2026 Yiu.pdf (p33)

Management of Congenital Diaphragmatic Hernia

This is the single most important concept in CDH management. The instinct of many students is to think: "there's a hole in the diaphragm → fix the hole." But the reality is:

The baby does not die from the hernia. The baby dies from pulmonary hypoplasia and persistent pulmonary hypertension. The operation can wait — stabilisation cannot. ^[3]^[4]^[6]

The current paradigm (since the landmark shift in the late 1990s–2000s) is "stabilise THEN operate" — sometimes called "gentle ventilation" or the "permissive hypercapnia" approach. The old approach of rushing to the operating theatre for immediate repair had unacceptably high mortality because the baby's physiology was not optimised.

B. Antenatal Management

Once CDH is diagnosed antenatally, the family needs comprehensive counselling based on prognostic markers:

Factor	Implication for Counselling
O/E LHR > 45%, liver DOWN, isolated CDH	Good prognosis (survival > 60–70%). Recommend continuing pregnancy with planned delivery at tertiary centre
O/E LHR 25–45%, or liver UP	Moderate-to-severe CDH. Discuss guarded prognosis. Consider referral for FETO in specialised centres
O/E LHR < 25%	Extremely poor prognosis (survival < 15%). Discuss palliative care options vs aggressive treatment including FETO
Complex CDH (major cardiac/chromosomal anomaly)	Significantly worse prognosis. Genetic counselling essential. Some anomalies (e.g., trisomy 18) may be incompatible with long-term survival

Senior note: "Antenatal: FETO procedure (foetal endoscopic tracheal occlusion)" ^[3]

What is FETO? A fetoscopic procedure performed at ~27–29 weeks of gestation, where a small balloon is placed in the fetal trachea via a fetoscope.

How does it work?

Normally, fetal lungs continuously secrete fluid that exits via the trachea into the amniotic cavity
If you occlude the trachea with a balloon, this fluid is trapped → the lungs distend → this mechanical stretch stimulates lung growth (both airway and vascular development)
The balloon is removed at ~34 weeks (either by a second fetoscopic procedure or by an EXIT procedure at delivery) to allow the lungs to mature and surfactant to be released

Senior note / lecture: "Fetal surgery: endotracheal balloon occlusion → tracheal obstruction in-utero promotes lung growth" ^[6]

Aspect	Detail
Indication	Severe isolated CDH with O/E LHR < 25–35% (depending on side and liver position). The TOTAL trial (2021) showed benefit for severe CDH
Timing	Balloon insertion ~27–29 weeks; balloon removal ~34 weeks
Benefit	Increases lung growth, may improve survival in severe CDH from ~15–25% to ~40–50%
Risks	Preterm premature rupture of membranes (PPROM, most common complication ~30%), preterm delivery, fetal bradycardia during procedure
Contraindications	Non-isolated CDH with major chromosomal/cardiac anomalies (the prognosis is already determined by the associated anomaly); maternal contraindications to fetoscopy
Availability	Only in specialised fetal medicine centres (in Hong Kong, referral may be needed to centres with fetal intervention expertise)

Planned delivery at a tertiary centre with paediatric surgery, neonatal ICU, and ideally ECMO capability ^[3]^[4]
Mode of delivery is based on obstetric indications — CDH alone is not an indication for Caesarean section
Timing: aim for term or near-term delivery (avoid iatrogenic prematurity, as prematurity worsens pulmonary hypoplasia). If FETO was performed, delivery may need to be earlier (34–37 weeks)
An EXIT (Ex Utero Intrapartum Treatment) procedure is rarely needed unless the FETO balloon has not been retrieved before delivery

This is the most critical and time-sensitive phase. The goals are:

Secure the airway without inflating the intrathoracic bowel
Decompress the stomach/bowel to prevent further lung compression
Establish monitoring

Step	Action	Rationale
1. DO NOT bag-mask ventilate	Avoid any positive pressure via facemask	Air enters the stomach and herniated bowel in the thorax → bowel distends → further compresses the already hypoplastic lung → catastrophic deterioration ^[1]^[3]^[4]^[6]
2. Immediate endotracheal intubation	Intubate as soon as CDH is suspected; use gentle ventilation	Directs air only into the lungs, not the GI tract. Allows controlled ventilation with appropriate pressures
3. NGT/OGT on free drainage or intermittent suction	Place a large-bore (8–10 Fr) orogastric or nasogastric tube on free drainage/low intermittent suction	Decompresses the stomach and intrathoracic bowel → reduces mass effect on the lung ^[3]^[4]^[6]
4. Pre-ductal and post-ductal SpO₂ monitoring	Right hand (pre-ductal) and either foot (post-ductal)	Monitors the degree of R-to-L shunting; guides therapy targets
5. IV access	Peripheral IV or umbilical venous catheter (UVC)	For fluids, medications, and blood sampling
6. Minimal handling	Avoid stimulation, keep warm, neutral thermal environment	Agitation and cold stress increase oxygen consumption and can trigger pulmonary vasospasm
7. Position	Place the baby with the affected side down (if left CDH, left lateral position)	Gravity helps keep the herniated viscera from further compressing the contralateral lung

Delivery Room Rule

NEVER bag-mask ventilate a baby with known or suspected CDH. This is one of the most high-yield neonatal resuscitation rules. Every second of bag-mask ventilation inflates the intrathoracic bowel and makes the respiratory failure worse. The neonatal team should be prepared for immediate intubation at birth. ^[1]^[3]^[4]^[6]

D. NICU Stabilisation Phase

The baby is transferred to the NICU. The goal is physiological stabilisation — NOT immediate surgery. Surgery is only performed once the baby is stable.

The modern approach avoids aggressive hyperventilation (which was the old strategy to cause alkalosis and reduce PVR). Instead, we use permissive hypercapnia — accepting a higher PaCO₂ to avoid ventilator-induced lung injury.

Parameter	Target	Rationale
Pre-ductal SpO₂	> 85% (ideally 85–95%)	Adequate systemic oxygenation. Avoid hyperoxia (high FiO₂ increases oxidative stress and does not help if the problem is structural)
PaCO₂	< 60–65 mmHg (permissive hypercapnia)	Accept mild hypercarbia rather than using high pressures that damage the hypoplastic lungs. Aggressive hyperventilation to achieve a low PaCO₂ causes barotrauma and volutrauma
pH	> 7.25	Maintain adequate acid-base status; avoid severe acidosis (which worsens pulmonary vasoconstriction)
Peak Inspiratory Pressure (PIP)	< 25 cmH₂O	Limit barotrauma. The hypoplastic lungs are fragile and easily damaged. Lower pressures reduce the risk of pneumothorax (especially of the contralateral lung)

Ventilation modes:

Mode	When Used	Details
Conventional Mechanical Ventilation (CMV)	First-line	Pressure-controlled or volume-targeted ventilation with gentle settings. Synchronised modes (SIMV, AC) preferred
High-Frequency Oscillatory Ventilation (HFOV)	If CMV fails (cannot maintain targets with PIP < 25)	Uses very small tidal volumes at very high rates (> 300/min) → maintains mean airway pressure for oxygenation while minimising peak pressure swings → reduces barotrauma. Often referred to as "HIFV" (high-frequency ventilation) in senior notes ^[3]
High-Frequency Jet Ventilation (HFJV)	Alternative to HFOV	Similar principle; less commonly used

Why NOT aggressive hyperventilation?

The old approach was to hyperventilate the baby to achieve a low PaCO₂ and respiratory alkalosis, because alkalosis was thought to reduce PVR. This required high ventilator pressures. However, studies showed this approach caused pneumothorax (especially of the contralateral "good" lung — the only functioning lung), chronic lung disease, and did not improve survival. The shift to gentle ventilation with permissive hypercapnia revolutionised CDH outcomes.

This is often the most challenging aspect of CDH management. The goal is to reduce PVR and break the vicious cycle of hypoxia → pulmonary vasoconstriction → R-to-L shunting → more hypoxia.

Agent	Mechanism	Details
Inhaled Nitric Oxide (iNO)	Potent selective pulmonary vasodilator. NO diffuses into pulmonary vascular smooth muscle → activates guanylate cyclase → increases cGMP → smooth muscle relaxation → pulmonary vasodilation. "Selective" because it is inhaled and acts only on ventilated lung units, then is rapidly inactivated by haemoglobin — minimal systemic effects	First-line pulmonary vasodilator for PPHN ^[3]^[4]. Starting dose 20 ppm. Important: in CDH, the response to iNO is often poor (~30–40% respond) because the pulmonary vascular abnormality is structural (muscularised vessels with reduced cross-sectional area), not just functional vasospasm. iNO works best when there is a reactive vasospastic component
Sildenafil (oral or IV)	PDE5 inhibitor — phosphodiesterase 5 normally breaks down cGMP. By inhibiting PDE5, sildenafil increases cGMP → sustained pulmonary vasodilation. "Sil-dena-fil" → think "cGMP filler"	Second-line pulmonary vasodilator, used when iNO alone is insufficient ^[4]. Can be given enterally (via NGT) or IV. Acts synergistically with iNO
Milrinone (IV)	PDE3 inhibitor — inhibits phosphodiesterase 3, which breaks down cAMP. Increased cAMP → positive inotropy (stronger cardiac contraction) + vasodilation (both pulmonary and systemic) → "inodilator"	Particularly useful when RV dysfunction is present (common in severe PPHN). Improves cardiac output while reducing PVR. Also reduces afterload
Prostacyclin analogues (e.g., epoprostenol, iloprost)	Prostacyclin → activates adenylate cyclase → increases cAMP → pulmonary vasodilation + antiplatelet effects	Inhaled iloprost can be used as rescue therapy. Less commonly first-line in neonates
Inotropes / vasopressors	Support systemic blood pressure and cardiac output	Dopamine, dobutamine, noradrenaline, adrenaline — used to maintain systemic blood pressure ABOVE pulmonary artery pressure (if systemic BP < PA pressure → R-to-L shunting worsens). Vasopressin is increasingly used as it raises SVR without significantly raising PVR

Senior note: "Correct pulmonary HT (HIFV, NO, inotropes)" ^[3]

Key principle: You need to raise SVR (systemic vascular resistance) relative to PVR to reverse the R-to-L shunt. This is achieved by:

Lowering PVR — iNO, sildenafil, milrinone
Raising SVR — vasopressors (noradrenaline, vasopressin)
Optimising cardiac output — inotropes (dobutamine, milrinone), volume resuscitation
Avoiding triggers of pulmonary vasoconstriction — hypoxia, acidosis, hypothermia, pain/agitation (use sedation/analgesia: morphine, fentanyl, midazolam)

Aspect	Action	Rationale
IV fluids and nutrition	IV dextrose initially; transition to TPN once lines are established	Baby is NPO (nil per os) — no enteral feeds until bowel is returned to the abdomen and function is established post-surgery
Sedation and analgesia	Morphine or fentanyl infusion; consider muscle relaxation (e.g., vecuronium) if ventilator dyssynchrony	Minimise agitation and pain → prevent catecholamine surges → prevent pulmonary vasospasm. Neuromuscular blockade may improve ventilator synchrony but should be used judiciously
Antibiotics	Empirical broad-spectrum antibiotics (e.g., ampicillin + gentamicin) until sepsis is ruled out	Sick neonates are at high risk for sepsis; difficult to clinically distinguish CDH from neonatal pneumonia initially
Correction of acidosis	Sodium bicarbonate (cautiously) or THAM if metabolic acidosis is severe; optimise ventilation for respiratory acidosis	Acidosis → pulmonary vasoconstriction → worsening PPHN
Blood products	Maintain Hb > 12–15 g/dL; correct coagulopathy with FFP/platelets if indicated	Adequate oxygen-carrying capacity; prepare for surgery/ECMO
Echocardiography	Serial assessment	Monitor PPHN trajectory, RV function, shunt direction — guides escalation/de-escalation of therapy

ECMO is the last resort for CDH babies who fail maximal medical therapy. ^[3]^[4]^[6]

What is ECMO? Think of it as a temporary external heart-lung machine. Blood is drained from the patient, passed through an oxygenator membrane (where CO₂ is removed and O₂ is added), warmed, and returned to the patient. It rests the lungs and heart while they recover.

Aspect	Detail
Indication	OI > 40 despite maximal medical therapy (iNO, HFOV, inotropes, sildenafil); failure to maintain pre-ductal SpO₂ > 80%; progressive metabolic acidosis despite maximal support
Types	Veno-arterial (VA) ECMO — blood drained from right internal jugular vein, returned via right common carotid artery. Provides both cardiac and respiratory support. Most commonly used in CDH. Veno-venous (VV) ECMO — blood drained and returned via venous system only. Provides respiratory support but not cardiac support
Contraindications	Lethal chromosomal anomaly; severe intracranial haemorrhage (ICH) (ECMO requires systemic heparinisation → ICH will worsen); gestational age < 34 weeks or weight < 2 kg (vessels too small for cannulation); irreversible pulmonary hypoplasia (no recovery possible)
Duration	Typically 1–3 weeks; prolonged ECMO (> 4 weeks) has diminishing returns
Complications	ICH (most feared — heparin-related), circuit thrombosis, haemolysis, infection, renal failure, need for right carotid artery ligation (VA ECMO)
Surgery on ECMO	CDH repair can be performed while the baby is on ECMO (the ECMO circuit provides oxygenation during surgery) or after decannulation

Senior note: "ECMO: for severe cases refractory to NO (~40% severe cases remain hypoxemic on iNO + max ventilation)" ^[4]

ECMO Decision

The decision to initiate ECMO should be made at a multidisciplinary team meeting including neonatology, paediatric surgery, and paediatric cardiothoracic surgery/ECMO team. Not all CDH babies are candidates — the baby must have a reasonable chance of lung recovery for ECMO to be a bridge to survival, not merely a delay of death.

E. Surgical Management

"Stabilise then operate" — surgery is performed only after the baby is physiologically stable.

Criterion for "Stable Enough for Surgery"	Target
Pre-ductal SpO₂	> 85% consistently
FiO₂	Trending down (ideally < 0.5)
PIP	< 25 cmH₂O
Echocardiographic evidence of improving PPHN	Decreasing PA pressures, bidirectional or L-to-R shunt at PDA/PFO
Adequate urine output	> 1 mL/kg/hr
Stable haemodynamics	Off or on low-dose inotropes, no escalating support
Lactate	Normal or trending down

Typically this stabilisation period is 24–72 hours, but may be longer in severe cases.

Approach	Details
Open repair (standard)	Subcostal incision on the affected side (abdominal approach). The herniated viscera are gently reduced back into the abdomen. The diaphragmatic defect is identified and repaired.
Thoracoscopic/laparoscopic repair	Minimally invasive approach; increasingly used in stable babies with smaller defects. Higher recurrence rate than open repair reported in some studies. Not appropriate for large defects or unstable babies.

Defect Size	Repair Method	Details
Small defect with adequate diaphragm rim	Primary repair — direct suturing of the diaphragm edges with interrupted non-absorbable sutures	Sufficient native diaphragm tissue exists to close the defect without tension. Best outcomes
Large defect or agenesis of hemidiaphragm	Patch repair — the defect is closed with a prosthetic patch (e.g., Gore-Tex/PTFE) or a biological graft (e.g., human acellular dermal matrix, porcine small intestinal submucosa)	When there is insufficient native diaphragm to close primarily. Higher recurrence rate (~30–50% for large patch repairs) compared to primary repair (~5–10%)
Large defect — muscle flap	Muscle flap repair — using latissimus dorsi or reversed internal oblique muscle flap to close the defect	Autologous tissue → may have growth potential (advantage in a growing child), but technically more demanding. "Direct repair with/without muscular flap" ^[3]

Senior note: "Surgery: Direct repair with/without muscular flap" ^[3]

Issue	Management
Reducing herniated viscera	Gently milk the bowel back into the abdomen. Inspect the bowel for viability, malrotation, and associated anomalies (Meckel diverticulum, intestinal atresia)
Malrotation	Almost universally present in left CDH. Most surgeons do NOT perform a formal Ladd procedure at CDH repair (adds operative time/stress). The malrotation is documented for future reference
Hernial sac	A peritoneal sac is present in ~10–20% of cases (usually smaller defects, better prognosis). If present, it should be excised
Abdominal closure	If the abdominal cavity is too small to accommodate the reduced viscera (because it was underdeveloped) → cannot close the abdomen primarily → may need a temporary silo (a Silastic bag/pouch attached to the abdominal wall edges) that is gradually reduced over days, similar to the approach used for gastroschisis. Forced closure → abdominal compartment syndrome (elevated intra-abdominal pressure → respiratory compromise, renal failure, bowel ischaemia)
Chest drain	Controversial. Some centres place a chest drain on the affected side; others do NOT (risk of mediastinal shift if the drain creates excessive negative pressure and pulls the mediastinum towards the affected side). If placed, it should be to water seal, NOT suction

Abdominal Compartment Syndrome

Trying to force all the herniated viscera into a small, underdeveloped abdominal cavity can cause abdominal compartment syndrome — elevated intra-abdominal pressure that compresses the IVC (reducing venous return), splints the diaphragm (worsening ventilation), and compresses the renal vessels (causing renal failure). Monitor intra-abdominal pressure via a bladder catheter post-operatively. If pressures are too high, re-open and place a temporary silo.

Aspect	Detail
Ventilation	Continue gentle ventilation strategy. The lungs do NOT suddenly grow after surgery — pulmonary hypoplasia and PPHN persist. Gradual weaning as tolerated
PPHN management	May continue iNO, sildenafil, milrinone post-operatively. Wean based on echocardiographic assessment
Nutrition	Begin enteral feeds cautiously once bowel function returns (passage of meconium, reducing NGT output). Many CDH survivors have significant GI dysmotility and GORD (gastro-oesophageal reflux) and may need prolonged parenteral nutrition
Monitoring for recurrence	CXR follow-up. Recurrence more common with patch repairs (~30–50%) vs primary repair (~5–10%). If recurrence suspected (respiratory symptoms, CXR showing bowel re-entering thorax) → re-operation
Monitoring for complications	See complications section (next)

Type	Management
Late-presenting Bochdalek hernia	Usually less severe pulmonary hypoplasia (since the lungs had more time to develop). Stabilise → elective surgical repair (same principles: reduce viscera, close defect). Less likely to need ECMO
Morgagni hernia	Typically presents late (childhood or adulthood). Usually contains omentum ± transverse colon. Repair is elective — laparoscopic approach is increasingly preferred. Primary closure of the anterior diaphragmatic defect with sutures or mesh. Prognosis is excellent because there is minimal pulmonary hypoplasia

Phase	Key Actions
Antenatal	Prognosticate (O/E LHR, liver, MRI, karyotype, echo). Consider FETO for severe cases. Plan delivery at tertiary centre
Delivery room	DO NOT bag-mask ventilate. Intubate immediately. NGT on free drainage. Pre-/post-ductal SpO₂ monitoring ^[1]^[3]^[4]^[6]
NICU stabilisation	Gentle ventilation (permissive hypercapnia, PIP < 25). iNO for PPHN. Inotropes. Sildenafil/milrinone as needed. Serial echo. NPO + TPN ^[3]^[4]
ECMO	If OI > 40 despite maximal therapy. VA ECMO most common. Bridge to recovery or surgery ^[3]^[4]
Surgery	After stabilisation. Primary repair or patch repair ± muscle flap. Avoid forced abdominal closure ^[3]
Post-operative	Continue ventilatory support + PPHN therapy. Cautious enteral feeding. Monitor for recurrence and long-term complications

High Yield Summary — Management of CDH

CDH management = stabilise first, operate later — surgery is NOT the emergency; controlling PPHN is ^[3]^[4]
NEVER bag-mask ventilate — intubate and insert NGT immediately ^[1]^[3]^[4]^[6]
Gentle ventilation: permissive hypercapnia (PaCO₂ < 60-65), low PIP (< 25 cmH₂O), target pre-ductal SpO₂ > 85%
iNO is first-line for PPHN; response is often poor in CDH (structural vascular disease, not just vasospasm) ^[3]^[4]
Sildenafil (PDE5 inhibitor) is second-line; milrinone (PDE3 inhibitor / inodilator) for RV dysfunction
ECMO for OI > 40 despite maximal medical therapy; contraindicated if lethal anomaly, ICH, or weight < 2 kg ^[3]^[4]
FETO (fetal endoscopic tracheal occlusion) at 27-29 weeks for severe CDH (O/E LHR < 25-35%) — promotes in utero lung growth by trapping fetal lung fluid ^[3]^[6]
Surgical repair: primary closure for small defects; patch/muscle flap for large defects or diaphragm agenesis ^[3]
Risk of abdominal compartment syndrome if viscera forced into underdeveloped abdominal cavity — use temporary silo if needed
Long-term follow-up essential: GORD, chronic lung disease, neurodevelopmental delay, hearing loss, scoliosis, hernia recurrence

Active Recall - Management of CDH

References

^[1] Lecture slides: GC 204. The newborn baby cannot breathe Oesophageal atresia, diaphragmatic hernia, and other surgery of lung.pdf ^[2] Lecture slides: Neonatal Surgery.pdf ^[3] Senior notes: Maksim Surgery Notes.pdf (p333) ^[4] Senior notes: Adrian Lui Pediatrics Notes.pdf (p54) ^[6] Senior notes: Maksim Paediatric Notes.pdf (p69) ^[8] Lecture slides: GC 205. The newborn baby is vomiting repeatedly Neonatal intestinal obstruction and other GI emergencies.pdf

Complications of Congenital Diaphragmatic Hernia

CDH complications are best understood in two time frames: acute/peri-operative complications (the immediate threats to life) and long-term sequelae (the chronic issues that CDH survivors live with). Both arise from the same fundamental pathology — the lungs and their vasculature are structurally abnormal, and the prolonged intensive care required to keep these babies alive carries its own morbidity.

Senior note: "Cx: lung hypoplasia, pulmonary HT, hearing defects" ^[3]

Senior note: "Other long-term sequelae: abnormal lung function, neurological/growth disturbance, scoliosis" ^[4]

A. Acute / Peri-Operative Complications

These occur in the neonatal period, during stabilisation, ECMO, or around the time of surgery.

Aspect	Detail
Frequency	Present in virtually all symptomatic CDH at birth; the severity varies
Pathophysiology	The pulmonary arterioles are structurally abnormal — hypermuscularised, reduced in number, with blunted vasodilator responses. High PVR → R-to-L shunting → systemic hypoxemia. Postnatal triggers (hypoxia, acidosis, hypothermia) amplify this
Why it matters	PPHN is the leading cause of death in CDH. The degree of PPHN and the lung's ability to respond to vasodilator therapy determine survival
Clinical consequence	Refractory cyanosis, cardiovascular collapse, multi-organ failure
Management	iNO, sildenafil, milrinone, inotropes, ECMO (as discussed in management section)

PPHN can be thought of as both a complication and an intrinsic feature of CDH. It is the physiological expression of the underlying pulmonary vascular hypoplasia and remodelling.

Aspect	Detail
Risk	High — especially of the contralateral ("good") lung
Pathophysiology	The contralateral lung is the baby's only functioning lung. Aggressive ventilation (high PIP, high tidal volumes) can overdistend it → alveolar rupture → pneumothorax. This is why the gentle ventilation strategy (PIP < 25 cmH₂O, permissive hypercapnia) is so important
Why contralateral?	The ipsilateral lung is hypoplastic and compressed — there is not much lung tissue to rupture. The contralateral lung receives the majority of ventilation and is at greatest risk of barotrauma
Consequence	Catastrophic — the baby loses the only functioning lung. Rapid cardiovascular collapse. Requires immediate needle decompression followed by chest drain
Prevention	Gentle ventilation, HFOV if CMV fails, avoid aggressive hyperventilation

Pneumothorax in CDH

A pneumothorax of the contralateral lung in CDH is a life-threatening emergency. The baby has only one functioning lung, and if that lung collapses, there is essentially no gas exchange at all. This is why the gentle ventilation strategy (PIP < 25 cmH₂O) is not optional — it is lifesaving.

Aspect	Detail
What it is	The lungs are structurally underdeveloped with reduced bronchial branching, reduced alveolar count, and thickened alveolar septa
Why it is a complication	The degree of pulmonary hypoplasia is the single most important determinant of survival. ^[1]^[2]^[8] If both lungs are too hypoplastic, there is simply not enough gas exchange surface area to sustain life, regardless of ventilatory support or ECMO
Irreversibility	Pulmonary hypoplasia is fixed at birth — the lungs cannot grow new bronchial branches or alveoli after delivery (some alveolar multiplication does occur in infancy, but the structural deficit is permanent). Postnatal lung growth can partially compensate over years, but never fully normalises

GC lecture slide: "Herniated abdominal contents prevents lung growth" — this is the fundamental reason for pulmonary hypoplasia and the root cause of both acute mortality and long-term respiratory morbidity ^[1]^[2]^[8]

Complication	Mechanism
Right ventricular failure	Chronically elevated PVR from PPHN → RV pressure overload → RV dilation and dysfunction → decreased cardiac output → systemic hypotension and end-organ hypoperfusion
Left ventricular hypoplasia (in severe CDH)	In severe left CDH, the heart may be chronically compressed and displaced in utero → LV may be underdeveloped. Postnatally, the LV receives less preload (because blood is being shunted R-to-L) → reduced LV output
Associated structural cardiac anomalies	~20–30% have associated congenital heart defects (VSD, ASD, coarctation, TOF) ^[4]. These add to the haemodynamic burden and may require separate surgical intervention

For babies requiring ECMO, the complications of ECMO itself become significant:

Complication	Mechanism
Intracranial haemorrhage (ICH)	Most feared complication. Systemic heparinisation is required to prevent circuit thrombosis → haemorrhagic risk. Neonatal brain is inherently vulnerable (germinal matrix haemorrhage). Incidence ~10–15% in neonates on ECMO
Circuit thrombosis	Clot formation in the ECMO circuit despite heparin → circuit failure, embolic events
Haemolysis	Mechanical shearing of RBCs as blood passes through the pump and oxygenator → anaemia, hyperbilirubinaemia
Infection	Indwelling vascular cannulae → line-related bloodstream infection
Renal failure	Multifactorial — hypoperfusion, nephrotoxic drugs, haemolysis (haemoglobin-induced tubular injury). Many ECMO babies require continuous renal replacement therapy (CRRT)
Carotid artery ligation (VA ECMO)	The right common carotid artery is ligated during VA ECMO cannulation → theoretical risk of right hemispheric ischaemia. In practice, collateral circulation via the circle of Willis usually compensates, but there is concern about long-term neurovascular consequences

Aspect	Detail
Frequency	Primary repair: ~5–10% recurrence. Patch repair: ~30–50% recurrence
Why it happens	Large defects repaired with a prosthetic patch have no growth potential — as the child grows, the fixed-size patch may separate from the surrounding diaphragm. Native diaphragm tissue used in primary repair can grow with the child
Timing	Can occur months to years after initial repair
Presentation	Recurrent respiratory symptoms, feeding difficulties, bowel obstruction, bowel loops visible above the diaphragm on CXR
Management	Re-operation — re-repair with larger patch or muscle flap

Aspect	Detail
When	Immediately post-operative if the viscera are forced into the underdeveloped abdominal cavity
Mechanism	Raised intra-abdominal pressure → compression of IVC (reduced venous return → reduced cardiac output), compression of renal vessels (oliguria/anuria), splinting of the diaphragm (worsening ventilation), bowel ischaemia
Prevention	Avoid forced primary abdominal closure. Use a temporary silo if needed
Monitoring	Intravesical (bladder) pressure measurement

B. Long-Term Complications / Chronic Sequelae

CDH survivors — even those who do well in the neonatal period — require lifelong multidisciplinary follow-up. The long-term sequelae are numerous and affect virtually every organ system.

Issue	Mechanism	Clinical Impact
Abnormal lung function	Persistent pulmonary hypoplasia. The lungs never fully catch up. Reduced FEV₁, reduced FVC, air trapping, obstructive and/or restrictive patterns on spirometry	The most common long-term problem. ~50–70% of CDH survivors have abnormal lung function tests, even if clinically well. Exercise intolerance, recurrent lower respiratory tract infections
Chronic respiratory symptoms	Reduced airway calibre, airway hyperreactivity (similar to asthma — the hypoplastic airways are more reactive), recurrent pneumonia	Recurrent wheeze, cough, exercise-induced dyspnoea
Bronchopulmonary dysplasia (BPD)	Prolonged mechanical ventilation and oxygen therapy in the neonatal period → oxygen toxicity and ventilator-induced lung injury → chronic lung disease of prematurity (if premature) or a BPD-like picture (even in term CDH babies)	Chronic oxygen dependency, prolonged hospital stay
Compensatory lung growth	Over months to years, the remaining lung tissue undergoes compensatory hyperplasia (increase in alveolar number and size)	Partially offsets the hypoplasia — many CDH survivors are able to lead relatively normal lives by school age, but lung function never fully normalises

Senior note: "abnormal lung function" as a long-term sequela ^[4]

Aspect	Detail
Mechanism	The structurally abnormal pulmonary vasculature may never fully normalise. Some CDH survivors have persistent or recurrent pulmonary hypertension, especially during respiratory illnesses or exercise
Clinical impact	Exercise intolerance, right heart failure in severe cases
Monitoring	Serial echocardiography through childhood
Management	Oral pulmonary vasodilators (sildenafil, bosentan) for chronic pulmonary hypertension

Aspect	Detail
Frequency	Very common — affects ~40–80% of CDH survivors
Mechanism	Multiple factors: (1) Altered anatomy of the gastro-oesophageal junction (the crura may be disrupted, the angle of His altered, the lower oesophageal sphincter (LOS) incompetent); (2) Abnormal oesophageal motility; (3) Increased abdominal pressure after visceral reduction; (4) Abnormal gastric position/rotation
Clinical impact	Vomiting, failure to thrive, aspiration pneumonia (worsening the already compromised lungs), oesophagitis, feeding aversion
Management	Proton pump inhibitors (PPIs), prokinetics (domperidone), upright positioning after feeds, small frequent feeds. Anti-reflux surgery (Nissen fundoplication) may be required in severe cases (~20–30%)

Aspect	Detail
Frequency	Common — affects ~50% of CDH survivors
Mechanism	Multifactorial: GORD (above), oral aversion (from prolonged intubation/NPO/NGT), oesophageal dysmotility, intestinal dysmotility (herniated bowel may have abnormal innervation), high metabolic demands from chronic lung disease
Clinical impact	Poor weight gain, growth faltering, need for tube feeding (NG or gastrostomy). Many CDH survivors require supplemental tube feeding well into infancy/early childhood
Management	Dietitian input, high-calorie feeds, occupational therapy for oral aversion, gastrostomy tube (PEG/surgical) if oral feeding is insufficient

Senior note: "neurological/growth disturbance" ^[4]

Aspect	Detail
Frequency	~30–50% of CDH survivors have some degree of neurodevelopmental impairment
Mechanism	(1) Perinatal hypoxia-ischaemia — the brain is exposed to recurrent hypoxic episodes during the neonatal period; (2) ECMO-related — intracranial haemorrhage, carotid artery ligation; (3) Prolonged hospitalisation and ICU stay — sensory deprivation, lack of normal parent-infant bonding; (4) General anaesthesia — repeated anaesthetic exposure in a developing brain
Clinical impact	Cognitive delay, motor delay, speech/language delay, learning difficulties, behavioural problems (ADHD, autism spectrum features have been reported at higher rates). Gross motor delay may be more prominent due to trunk hypotonia and respiratory limitations
Monitoring	Formal neurodevelopmental assessment (e.g., Bayley Scales) at regular intervals (6 months, 12 months, 2 years, school entry)
Management	Early intervention programmes, physiotherapy, occupational therapy, speech therapy, educational support

Aspect	Detail
Frequency	~15–30% of CDH survivors
Mechanism	(1) Ototoxic medications — aminoglycosides (gentamicin) and loop diuretics (furosemide) used during NICU stay; (2) ECMO — both direct ototoxicity from circuit-related factors and haemodynamic instability/hypoxia affecting the cochlea; (3) Perinatal hypoxia — the cochlea is highly oxygen-dependent
Monitoring	Hearing screening (OAE — otoacoustic emissions — and/or ABR — auditory brainstem response) before discharge and at regular intervals through childhood
Management	Hearing aids, cochlear implants if severe bilateral SNHL, speech therapy

Senior note: "hearing defects" ^[3]

High Yield — Hearing Loss in CDH

Hearing loss is a frequently tested and frequently forgotten complication of CDH. It is multifactorial (ototoxic drugs, ECMO, hypoxia) and can be missed if auditory screening is not performed. All CDH survivors must have formal hearing assessment before NICU discharge and regular audiological follow-up. ^[3]

Complication	Mechanism	Management
Scoliosis	Asymmetric chest wall development (one hemithorax is underdeveloped/differently shaped); asymmetric diaphragm muscle pull after repair; chest wall deformity from the original defect	Regular spinal surveillance (clinical examination + spinal radiographs). Bracing or surgical correction if progressive
Pectus deformity (pectus excavatum or carinatum)	Similar mechanism — asymmetric thoracic growth, altered intrathoracic pressures	Observation; surgical correction (Nuss/Ravitch) if functionally significant
Chest wall asymmetry	The affected hemithorax is often smaller with reduced rib spacing	Usually cosmetic; may contribute to restrictive lung function

Senior note: "scoliosis" as a long-term sequela ^[4]

Complication	Mechanism
Intestinal obstruction	Adhesions from abdominal surgery (adhesive small bowel obstruction — the most common cause of bowel obstruction after any abdominal surgery). Can present months to years later with vomiting, abdominal distension, and colicky pain
Malrotation and risk of volvulus	Almost all left-sided CDH babies have malrotation (bowel never completed normal rotation because it was in the thorax). Malrotation predisposes to midgut volvulus at any point in life. Symptoms: bilious vomiting, acute abdomen. Emergency: Ladd procedure
Small bowel dysmotility	Herniated bowel may have abnormal myenteric plexus development → functional intestinal dysmotility → chronic feeding intolerance, pseudo-obstruction

Complication	Detail
Neurocognitive impairment	ICH, carotid ligation, and prolonged haemodynamic instability during ECMO contribute to higher rates of neurodevelopmental problems compared to CDH survivors who did not require ECMO
Chronic kidney disease	AKI during ECMO (from hypoperfusion, haemolysis, nephrotoxins) may progress to CKD in some cases

System	Acute	Long-Term
Respiratory	PPHN, pneumothorax, ventilator-induced lung injury	Chronic lung disease, abnormal PFTs, recurrent infections, BPD, chronic pulmonary hypertension
Cardiovascular	RV failure, LV hypoplasia, associated CHD	Chronic pulmonary hypertension, RV dysfunction
Gastrointestinal	Abdominal compartment syndrome	GORD, feeding difficulties, FTT, adhesive SBO, risk of midgut volvulus from malrotation
Neurological	Perinatal hypoxic brain injury, ECMO-related ICH	Neurodevelopmental delay, cognitive/motor/speech impairment, behavioural problems
Hearing	Ototoxic drug exposure	Sensorineural hearing loss (15–30%) ^[3]
Musculoskeletal	—	Scoliosis, pectus deformity, chest wall asymmetry ^[4]
Surgical	Hernia recurrence (patch > primary), wound complications	Hernia recurrence, adhesive bowel obstruction
ECMO-related	ICH, circuit thrombosis, haemolysis, infection, renal failure	Neurocognitive impairment, CKD, carotid stenosis

CDH survivors require structured, multidisciplinary long-term follow-up. Most CDH centres use a standardised follow-up programme:

Specialty	Monitoring
Paediatric surgery	Hernia recurrence surveillance (CXR); bowel function; GORD assessment
Respiratory / Pulmonology	Lung function tests from age ~5; clinical assessment for respiratory symptoms; chronic pulmonary hypertension screening
Cardiology	Serial echocardiography for pulmonary hypertension and cardiac function
Audiology	Hearing assessment before NICU discharge and at regular intervals ^[3]
Neurodevelopment	Formal developmental assessment at 6, 12, 24 months and school entry; ongoing educational support
Nutrition / Dietetics	Growth monitoring, feeding support, caloric supplementation
Orthopaedics	Spinal surveillance for scoliosis; chest wall assessment
Psychology	Behavioural and emotional support for the child and family

High Yield Summary — Complications of CDH

PPHN is the leading cause of acute mortality in CDH — it is both a feature and a complication of the disease
Pneumothorax of the contralateral lung is the most feared ventilatory complication — prevented by gentle ventilation strategy (PIP < 25 cmH₂O)
Pulmonary hypoplasia is irreversible at birth — the degree determines survival ^[1]^[2]^[8]
~20–30% have associated cardiac anomalies that add to haemodynamic burden ^[4]
Hernia recurrence: ~5–10% after primary repair, ~30–50% after patch repair
GORD affects 40–80% of survivors — multifactorial (disrupted GOJ anatomy, oesophageal dysmotility, raised IAP post-repair)
Neurodevelopmental delay in ~30–50% — from perinatal hypoxia, ECMO complications, prolonged ICU stay
Sensorineural hearing loss in ~15–30% — from ototoxic drugs (aminoglycosides, furosemide), ECMO, hypoxia ^[3]
Scoliosis from asymmetric thoracic development ^[4]
Abnormal lung function is the most common long-term morbidity — ~50–70% have abnormal PFTs even if clinically well ^[4]
Malrotation is universal in left CDH and carries lifelong risk of midgut volvulus
All CDH survivors need structured multidisciplinary follow-up through childhood and beyond

Active Recall - Complications of CDH

References

^[1] Lecture slides: GC 204. The newborn baby cannot breathe Oesophageal atresia, diaphragmatic hernia, and other surgery of lung.pdf ^[2] Lecture slides: Neonatal Surgery.pdf ^[3] Senior notes: Maksim Surgery Notes.pdf (p333) ^[4] Senior notes: Adrian Lui Pediatrics Notes.pdf (p54) ^[6] Senior notes: Maksim Paediatric Notes.pdf (p69) ^[8] Lecture slides: GC 205. The newborn baby is vomiting repeatedly Neonatal intestinal obstruction and other GI emergencies.pdf

High Yield Summary

CDH = a defect in the diaphragm allowing abdominal viscera into the thorax, causing pulmonary hypoplasia and PPHN ^[1]^[2]
Bochdalek (posterolateral) hernia is the most common type (~80–90%), left-sided in ~80% ^[1]^[2]
Left > right because the left pleuroperitoneal canal closes later in embryological development ^[1]
Clinical triad: acute respiratory distress + cyanosis + scaphoid abdomen ^[1]
The severity depends on the degree of pulmonary hypoplasia — this is the main determinant of survival
PPHN creates a vicious cycle: hypoxia → vasoconstriction → R-to-L shunting → more hypoxia
Pre-ductal SpO₂ > post-ductal SpO₂ = evidence of right-to-left ductal shunting
NEVER bag-mask ventilate — intubate and insert NGT immediately ^[1]^[2]
~40–50% have associated anomalies; cardiac anomalies are the most common
Morgagni hernia (anterior) is rare and often presents late in life
Malrotation is essentially universal in left-sided CDH
Antenatal prognostic markers: O/E LHR, liver position (UP = worse), total fetal lung volume on MRI

High Yield Summary — Differential Diagnosis of CDH

The classic triad (respiratory distress + cyanosis + scaphoid abdomen) with absent breath sounds and bowel sounds in the chest is virtually pathognomonic for CDH
CPAM is the most important antenatal mimic — differentiate by confirming the mass is pulmonary tissue, not bowel (no peristalsis, stomach in abdomen)
Pneumothorax is the most important postnatal mimic — differentiate by visible collapsed lung edge on CXR, no bowel gas pattern in thorax
CXR is the key discriminating investigation — bowel loops above the diaphragm with mediastinal shift + gasless/paucity of gas in the abdomen = CDH
For cyanotic CHD, use the hyperoxia test and echocardiography — CDH will partially respond to O₂, CHD will not
NGT position on CXR helps differentiate CDH (tip in thorax) from OA (coiled in upper pouch)
GC slide: "Worse prognosis with earlier diagnosis" refers to severity (larger defects detected earlier), not a causal effect of prenatal diagnosis itself ^[8]
Malrotation is essentially universal in left CDH — always consider midgut volvulus as a concurrent or future surgical concern ^[3]^[5]

High Yield Summary — Diagnosis of CDH

Antenatal USS is the primary diagnostic tool — most CDH is now diagnosed before birth ^[4]^[8]
CXR is the first-line postnatal investigation — bowel loops in thorax + mediastinal shift + gasless abdomen = CDH ^[3]^[6]
NGT tip in the thorax on CXR means the stomach is herniated — virtually confirms CDH
Pre-ductal SpO₂ (right hand) > post-ductal SpO₂ (foot) with > 5–10% gradient = significant R-to-L ductal shunting ^[4]
Absence of pre-post ductal gradient does NOT rule out PPHN — shunting may be via PFO instead of PDA ^[4]
Echocardiography is essential in every CDH case — to assess PPHN severity AND rule out associated structural CHD
ABG: PaO₂ should reach > 100 mmHg at least once early on — if PaO₂ NEVER rises above 100 on 100% O₂, suspect cyanotic CHD instead ^[4]
Prognostic markers: O/E LHR, liver position, TFLV on MRI, associated anomalies, best PaO₂ in first 24h, OI
OI > 40 on maximal medical therapy → consider ECMO referral
All CDH neonates need karyotype/microarray + fetal/neonatal echocardiography + renal USS to screen for associated anomalies

High Yield Summary — Management of CDH

CDH management = stabilise first, operate later — surgery is NOT the emergency; controlling PPHN is ^[3]^[4]
NEVER bag-mask ventilate — intubate and insert NGT immediately ^[1]^[3]^[4]^[6]
Gentle ventilation: permissive hypercapnia (PaCO₂ < 60-65), low PIP (< 25 cmH₂O), target pre-ductal SpO₂ > 85%
iNO is first-line for PPHN; response is often poor in CDH (structural vascular disease, not just vasospasm) ^[3]^[4]
Sildenafil (PDE5 inhibitor) is second-line; milrinone (PDE3 inhibitor / inodilator) for RV dysfunction
ECMO for OI > 40 despite maximal medical therapy; contraindicated if lethal anomaly, ICH, or weight < 2 kg ^[3]^[4]
FETO (fetal endoscopic tracheal occlusion) at 27-29 weeks for severe CDH (O/E LHR < 25-35%) — promotes in utero lung growth by trapping fetal lung fluid ^[3]^[6]
Surgical repair: primary closure for small defects; patch/muscle flap for large defects or diaphragm agenesis ^[3]
Risk of abdominal compartment syndrome if viscera forced into underdeveloped abdominal cavity — use temporary silo if needed
Long-term follow-up essential: GORD, chronic lung disease, neurodevelopmental delay, hearing loss, scoliosis, hernia recurrence

High Yield Summary — Complications of CDH

PPHN is the leading cause of acute mortality in CDH — it is both a feature and a complication of the disease
Pneumothorax of the contralateral lung is the most feared ventilatory complication — prevented by gentle ventilation strategy (PIP < 25 cmH₂O)
Pulmonary hypoplasia is irreversible at birth — the degree determines survival ^[1]^[2]^[8]
~20–30% have associated cardiac anomalies that add to haemodynamic burden ^[4]
Hernia recurrence: ~5–10% after primary repair, ~30–50% after patch repair
GORD affects 40–80% of survivors — multifactorial (disrupted GOJ anatomy, oesophageal dysmotility, raised IAP post-repair)
Neurodevelopmental delay in ~30–50% — from perinatal hypoxia, ECMO complications, prolonged ICU stay
Sensorineural hearing loss in ~15–30% — from ototoxic drugs (aminoglycosides, furosemide), ECMO, hypoxia ^[3]
Scoliosis from asymmetric thoracic development ^[4]
Abnormal lung function is the most common long-term morbidity — ~50–70% have abnormal PFTs even if clinically well ^[4]
Malrotation is universal in left CDH and carries lifelong risk of midgut volvulus
All CDH survivors need structured multidisciplinary follow-up through childhood and beyond

Congenital Diaphragmatic Hernia

1. Definition

2. Epidemiology

Why is the left side more common?

Hong Kong Context

3. Anatomy and Function of the Diaphragm

3.1. Normal Anatomy

3.2. Embryology of the Diaphragm (Critical for Understanding CDH)

3.3. Types of Diaphragmatic Defects (by Location)

4. Etiology

4.1. General Causes

4.2. Pathogenesis — Why Does the Defect Occur?

5. Pathophysiology

5.1. Pulmonary Hypoplasia

5.2. Persistent Pulmonary Hypertension of the Newborn (PPHN)

5.3. Mediastinal Shift

5.4. Abdominal Consequences

6. Classification

6.1. By Anatomical Location

6.2. By Severity (for Prognostication)

A. Lung-to-Head Ratio (LHR) / Observed-to-Expected LHR (O/E LHR)

B. Liver Position

C. CDH Study Group Staging

6.3. Isolated vs. Non-Isolated (Complex) CDH [1]

7. Clinical Features

7.1. Antenatal Presentation

7.2. Postnatal Presentation — Symptoms

7.3. Postnatal Presentation — Signs

7.4. Late-Presenting CDH (Beyond the Neonatal Period)

8. Key Pathophysiological Correlations Summary

9. Associated Anomalies

10. Summary of Key Anatomical and Pathophysiological Points (Before DDx/Ix/Mx)

Active Recall - Congenital Diaphragmatic Hernia (Definition, Epidemiology, Anatomy, Etiology, Pathophysiology, Clinical Features)

References

Overview: The Clinical Problem You Are Trying to Solve

A. Differential Diagnosis Framework

B. Detailed Differential Diagnosis

B1. Conditions Mimicking CDH on Antenatal Ultrasound

B2. Conditions Causing Acute Neonatal Respiratory Distress (Postnatal DDx)

B3. Conditions Causing Scaphoid Abdomen in the Newborn

C. Systematic Approach to Differentiating CDH from Mimics

D. Late-Presenting CDH — DDx Considerations

E. Key Discriminating Investigations for DDx (Brief — Full Ix in Next Section)

F. Summary Table: "Why This Is Not CDH"

Active Recall - Differential Diagnosis of CDH

A. Diagnostic Criteria

B. Diagnostic Algorithm

B1. Antenatal Diagnostic Pathway

B2. Postnatal Diagnostic Pathway

C. Investigation Modalities — Detailed

C1. Antenatal Investigations

i. Antenatal Ultrasound (First-Line)

ii. Fetal MRI

iii. Amniocentesis / Karyotyping

iv. Fetal Echocardiography

C2. Postnatal Investigations

i. Chest X-Ray + Abdominal X-Ray (CXR/AXR) — First-Line, Immediate

ii. Pulse Oximetry — Pre-ductal and Post-ductal

iii. Arterial Blood Gas (ABG)

iv. Echocardiography — Essential

v. Blood Investigations (Baseline)

vi. Additional Imaging (Selected Cases)

D. Prognostic Assessment — Putting It All Together

E. Summary of Diagnostic Approach

Active Recall - Diagnosis and Investigations of CDH

Core Principle: CDH Is a Medical Emergency Before It Is a Surgical One

A. Management Algorithm — Overview

B. Antenatal Management

B1. Counselling and Prognostication

B2. Fetal Endoscopic Tracheal Occlusion (FETO)

B3. Delivery Planning

C. Immediate Postnatal Management (Delivery Room Resuscitation)

D. NICU Stabilisation Phase

D1. Ventilation Strategy — "Gentle Ventilation"

D2. Management of PPHN

D3. Supportive Care in NICU

D4. ECMO (Extracorporeal Membrane Oxygenation)

E. Surgical Management

E1. Timing of Surgery

E2. Surgical Approach