Quick Answer
Congenital diaphragmatic hernia is a NEET PG paediatric surgery classic — embryology, immediate management traps and delayed surgical repair are recurrent themes. Fix these:
- Incidence 1 in 2500 live births; failure of pleuroperitoneal membrane fusion at 8 to 10 weeks.
- Bochdalek is posterolateral (70 to 90 percent), left-sided 80 to 85 percent; neonatal presentation.
- Morgagni is anterior retrosternal, small, often incidental in adults or older children.
- Prenatal diagnosis at the 20-week anomaly scan; o/e LHR and liver position predict severity.
- Do NOT bag-mask ventilate a suspected CDH — immediately intubate and decompress with an NG tube.
- Gentle ventilation with low peak pressures, permissive hypercapnia, preductal saturations 85 to 95 percent.
- Pulmonary hypertension therapy — iNO 20 ppm, sildenafil, milrinone; PGE1 to keep the ductus open.
- ECMO for refractory hypoxaemia or severe pulmonary hypertension despite maximal medical therapy.
- Surgical repair is NOT emergency — deferred to 48 hours to 5 days after stabilisation.
- Survival 70 to 80 percent at tertiary centres; multidisciplinary long-term follow-up.
Congenital diaphragmatic hernia (CDH) is a compulsory read for NEET PG paediatric surgery and neonatology — embryology, prenatal severity assessment, the immediate management trap around bag-mask ventilation, and delayed elective surgical repair recur in almost every recent paper. This deep dive walks through the four anatomical types, physiology, management and Indian tertiary-centre realities.
Embryology and pathophysiology
- The diaphragm forms between weeks 4 and 12 from four components — septum transversum (central tendon), pleuroperitoneal membranes (posterolateral portions), dorsal oesophageal mesentery (crura), and body wall muscle.
- Failure of the pleuroperitoneal membrane to fuse by 8 to 10 weeks leaves a posterolateral defect (Bochdalek).
- Abdominal viscera (small bowel, colon, stomach, spleen, sometimes liver) herniate into the thorax under negative intrathoracic pressure.
- The developing ipsilateral lung is compressed, producing pulmonary hypoplasia — reduced airway generations, alveolar number and cross-sectional pulmonary vascular bed.
- The contralateral lung is also hypoplastic though less severely.
- The reduced pulmonary vascular bed with abnormally muscularised arterioles produces persistent pulmonary hypertension — right-to-left shunting through the ductus and foramen ovale, hypoxaemia, cardiac failure.
Anatomical types
- Bochdalek (70 to 90 percent) — posterolateral defect; 80 to 85 percent left-sided (right side protected by the liver); presents as neonatal respiratory distress.
- Morgagni (2 to 6 percent) — anterior retrosternal defect; small; often asymptomatic and picked up incidentally on a later chest radiograph, or with obstruction of herniated omentum or bowel.
- Central (rare) — near the central tendon.
- Hiatal (rare in paediatric context) — the adult sliding or paraesophageal hiatal hernia is a separate condition presenting with reflux, managed by different principles (PPI, fundoplication if severe).
Prenatal diagnosis and severity
- Routine anomaly ultrasound at 18 to 22 weeks detects most Bochdalek CDH.
- Findings — stomach or bowel loops in the thorax, mediastinal shift, absent stomach in the abdomen, polyhydramnios, small abdominal circumference.
- Fetal MRI for detailed anatomy and lung volume.
- Observed-to-expected lung-to-head ratio (o/e LHR) — under 25 percent predicts very severe pulmonary hypoplasia, 25 to 45 percent severe, over 45 percent milder.
- Liver position — liver-up (herniated into the thorax) worse than liver-down.
- Right-sided CDH — rarer, larger, worse.
- Associated anomalies (about 40 percent) — chromosomal (trisomy 18 and 13, Turner), cardiac defects, neural tube defects; karyotype or microarray and fetal echocardiography are offered.
- Fetal genetics counselling and delivery planning at a tertiary NICU with ECMO capability.
Fetal intervention
- Fetoscopic endoluminal tracheal occlusion (FETO) — a temporary balloon placed in the fetal trachea between 27 and 32 weeks traps lung fluid, promoting lung growth; removed at 34 weeks. TOTAL trial showed modest survival benefit in severe left-sided CDH but with increased preterm birth. Available at a small number of specialised centres globally.
Postnatal presentation and immediate management
- Presentation — respiratory distress, cyanosis at birth, scaphoid abdomen, shifted heart sounds, audible bowel sounds in the chest.
- Do NOT bag-mask ventilate — inflates the herniated stomach and bowel, further compressing the hypoplastic lung, shifting the mediastinum and precipitating cardiovascular collapse.
- Immediate intubation to secure the airway.
- Large-bore orogastric or nasogastric tube on continuous suction to decompress the stomach and bowel.
- Gentle lung-protective ventilation — peak inspiratory pressure under 25 cm H2O, permissive hypercapnia up to 65 mmHg, preductal saturations 85 to 95 percent to avoid hyperoxia while preserving pulmonary vasodilatation.
- High-frequency oscillatory ventilation for refractory hypoxaemia despite conventional gentle settings.
- Avoid fluid overload — targeted fluid resuscitation only; inotropic support with dobutamine or noradrenaline for hypotension.
- Surfactant not routinely given — evidence lacking, may worsen outcomes.
Pulmonary hypertension management
- Inhaled nitric oxide (iNO) 20 ppm — selective pulmonary vasodilator; taper as pulmonary pressures improve.
- Sildenafil — oral or intravenous phosphodiesterase-5 inhibitor.
- Milrinone — phosphodiesterase-3 inhibitor with pulmonary vasodilatation and inotropic support.
- Bosentan — endothelin receptor antagonist in chronic pulmonary hypertension.
- Prostaglandin E1 (PGE1) — maintains ductal patency to allow right-to-left shunting and unload the right ventricle when systemic pulmonary pressures are supra-systemic.
- Echocardiography for serial assessment.
ECMO indications
- Refractory hypoxaemia (oxygenation index over 40) despite maximal medical therapy.
- Progressive circulatory failure.
- Available only at tertiary centres; veno-arterial or veno-venous.
- Improves survival in selected infants but not in those with very severe pulmonary hypoplasia.
Surgical repair
- Timing is NOT emergency.
- Deferred to 48 hours to 5 days after cardiorespiratory stabilisation (falling oxygenation index, resolution of pre- to post-ductal saturation gradient, echocardiographic improvement in pulmonary pressures).
- Open abdominal (subcostal) — commonest; viscera reduced from thorax and defect closed.
- Open thoracic — occasionally for delayed presentation or Morgagni.
- Minimally invasive — thoracoscopic or laparoscopic in selected stable neonates.
- Small defect — primary closure with non-absorbable sutures.
- Large defect (Type C, D of the CDH Study Group) — prosthetic patch (Gore-Tex, biological mesh) or a muscle flap.
- Post-repair complications — patch dehiscence and recurrence, pulmonary hypertension recurrence, GERD, adhesive obstruction, chylothorax, chronic lung disease.
Prognosis and long-term follow-up
- Survival at tertiary centres — 70 to 80 percent with modern management.
- Poor prognostic factors — first-hour presentation, low o/e LHR, liver-up position, right-sided defect, need for ECMO, large defect requiring patch, associated anomalies (chromosomal or major cardiac).
- Long-term complications — chronic lung disease with home oxygen and diuretics, persistent pulmonary hypertension, GERD (fundoplication in 20 to 30 percent), failure to thrive with gastrostomy feeding, sensorineural hearing loss (hypoxia, ECMO-related), neurodevelopmental delay, pectus and scoliosis, hernia recurrence particularly after patch repair.
- Multidisciplinary CDH follow-up clinic — paediatric surgery, pulmonology, cardiology, gastroenterology, audiology, physiotherapy, developmental paediatrics — through school age.
Comparing CDH with hiatal hernia (adult)
- Adult hiatal hernia is a distinct condition — the upper stomach herniates through the oesophageal hiatus, typically sliding (Type I) or paraesophageal (Type II to IV).
- Presents with GERD, dysphagia, chest pain, iron deficiency anaemia; risk of gastric volvulus in paraesophageal type.
- Management — PPI for reflux; laparoscopic fundoplication (Nissen, Toupet) for refractory reflux or paraesophageal hernia at risk of complications.
- Do not confuse with the neonatal CDH pathway.
India-specific context
- Antenatal detection rising with wider access to level-2 obstetric ultrasound and DBT-supported programmes; still uneven in rural districts.
- Limited ECMO centres — a handful of tertiary NICUs (AIIMS Delhi, PGI Chandigarh, CMC Vellore, Sri Sathya Sai Institute Puttaparthi, Kalinga Institute) offer neonatal ECMO; access remains a bottleneck.
- Antenatal transfer to a level-3 NICU is standard of care once CDH is diagnosed; peripheral delivery followed by postnatal transfer carries higher morbidity.
- Cost and consumables — nitric oxide, HFOV, ECMO circuits, prosthetic patches are all significant costs; PMJAY covers some tertiary interventions.
- Outcome gap — survival at Indian tertiary centres has improved to about 60 to 75 percent, approaching international benchmarks; peripheral outcomes remain lower because of delayed transfer, bag-mask ventilation before recognition, and limited pulmonary hypertension therapy.
- Long-term follow-up — infrequent and fragmented outside metro centres; parent support networks and telemedicine follow-up are expanding.
NEET PG MCQ traps
- Failure of pleuroperitoneal membrane fusion — Bochdalek CDH.
- Bochdalek 70 to 90 percent, left 80 to 85 percent, posterolateral.
- Morgagni — anterior retrosternal, small, often adult incidental.
- Incidence — 1 in 2500 live births.
- Anomaly scan at 20 weeks — stomach in thorax, mediastinal shift, absent abdominal stomach bubble.
- o/e LHR under 25 percent — very severe pulmonary hypoplasia.
- Liver-up — worse prognosis than liver-down.
- Do NOT bag-mask ventilate — intubate and NG-decompress instead.
- Gentle ventilation, permissive hypercapnia, preductal saturations 85 to 95 percent.
- iNO 20 ppm for pulmonary hypertension.
- Sildenafil and milrinone — added pulmonary vasodilators.
- PGE1 — keeps ductus open to unload right ventricle.
- Surgical repair is NOT emergency — deferred to 48 hours to 5 days.
- Large defect — prosthetic patch or muscle flap.
- ECMO — refractory hypoxaemia despite maximal medical therapy.
- Survival — 70 to 80 percent at tertiary centres.
- GERD, chronic lung disease, hearing loss, neurodevelopmental delay — common long-term morbidity.
- Associated anomalies (about 40 percent) — chromosomal, cardiac; offer karyotype and fetal echo.
- FETO — fetal endoscopic tracheal occlusion for severe left-sided CDH at selected centres.
- Scaphoid abdomen and bowel sounds in the chest — classic clinical clue at birth.
Frequently asked questions
What are the embryology and types of congenital diaphragmatic hernia and how are they distinguished?
The diaphragm forms between the 4th and 12th weeks of gestation from the septum transversum (central tendon), the pleuroperitoneal membranes (posterolateral portions), the dorsal mesentery of the oesophagus (crura), and the body wall muscle. Failure of the pleuroperitoneal membrane to fuse by 8 to 10 weeks allows abdominal viscera (small bowel, colon, stomach, spleen, sometimes liver) to herniate into the thorax, compressing the developing lung and causing pulmonary hypoplasia and a fixed pulmonary vascular bed prone to pulmonary hypertension. The four anatomical types are — Bochdalek (posterolateral, 70 to 90 percent, about 80 to 85 percent left-sided because the right side is protected by the developing liver, presents in the neonate with respiratory distress), Morgagni (anterior retrosternal, small, often asymptomatic and diagnosed later in life with an incidental chest radiograph or with obstruction of herniated omentum or bowel), central (rare, near the central tendon), and hiatal (rare in the paediatric context — the adult sliding or paraesophageal hiatal hernia is a different entity managed by different principles). Incidence of CDH is around 1 in 2500 live births, with a small male predominance.
How is congenital diaphragmatic hernia diagnosed prenatally and what predicts severity?
Routine second-trimester anomaly ultrasound at 18 to 22 weeks detects the majority of Bochdalek CDH. Findings include stomach or bowel loops in the thorax, mediastinal shift away from the herniated side, absent stomach in the abdomen, polyhydramnios (from oesophageal compression), and small abdominal circumference. Fetal MRI supplements ultrasound for anatomical detail and lung volume assessment. Severity is predicted by three parameters. First, the observed-to-expected lung-to-head ratio (o/e LHR) measures the contralateral lung area at the level of the four-chamber cardiac view divided by the head circumference — values below 25 percent predict very severe pulmonary hypoplasia, 25 to 45 percent severe, and above 45 percent milder. Second, the position of the liver — liver-up (herniated into the thorax) carries a worse prognosis than liver-down. Third, the side and size of the defect — right-sided CDH is rarer, larger and worse because the liver is bulkier. Associated anomalies occur in about 40 percent of cases — chromosomal (trisomy 18 and 13, Turner), cardiac defects, neural tube defects and CNS anomalies — so karyotype or microarray and detailed fetal echocardiography are offered.
Why is bag-mask ventilation contraindicated in a newborn with CDH and what is the correct immediate management?
A newborn with respiratory distress, cyanosis, a scaphoid abdomen, deviated heart sounds and audible bowel sounds in the chest at birth almost certainly has an antenatally undiagnosed CDH. Bag-mask ventilation inflates the herniated stomach and bowel loops sitting in the thorax; the further expansion compresses the already hypoplastic ipsilateral lung, shifts the mediastinum further and can cause acute cardiovascular collapse and death. The correct sequence is — do NOT bag-mask ventilate; immediately intubate the trachea to secure a definitive airway; pass a large-bore orogastric or nasogastric tube on continuous suction to decompress the stomach and bowel; ventilate gently with lung-protective settings (low peak inspiratory pressures under 25 cm H2O, permissive hypercapnia up to 65 mmHg, targeting preductal saturations 85 to 95 percent to avoid oxygen toxicity but preserve pulmonary vasodilatation); avoid extreme hyperoxia and fluid overload; keep the pulmonary vasodilatation strategy central — inhaled nitric oxide 20 ppm, intravenous sildenafil and milrinone are added for pulmonary hypertension; prostaglandin E1 maintains the patency of the ductus arteriosus to unload the right ventricle if there is severe systemic-to-pulmonary shunting; the baby is transported to a tertiary NICU with ECMO capability; surfactant is not routinely given (evidence for benefit is lacking and it may worsen outcomes).
When is surgical repair performed and what are the surgical options for CDH?
Surgical repair is NOT an emergency; it is performed after cardiorespiratory stabilisation, typically at 48 hours to 5 days, once pulmonary hypertension has improved (as evidenced by lower oxygenation index, resolution of pre- and post-ductal saturation gradient, normalising echocardiographic estimates of pulmonary pressure) and the infant is haemodynamically stable. Attempting early repair while the pulmonary vascular bed is reactive worsens outcomes. Approaches include open abdominal (subcostal incision, viscera reduced from the thorax and the defect closed) or open thoracic, and increasingly minimally invasive thoracoscopic or laparoscopic repair in selected stable neonates. Small defects are closed primarily with non-absorbable sutures; large defects (Type C and D under the CDH Study Group classification, with absent or very deficient diaphragm) require a prosthetic patch (Gore-Tex, biological mesh) or a muscle flap because of the wide defect. Post-repair complications include patch dehiscence and recurrence, pulmonary hypertension recurrence, GERD, adhesive intestinal obstruction, chylothorax and chronic lung disease.
What is the prognosis of CDH and what long-term follow-up is needed?
Survival at tertiary centres with modern management (gentle ventilation, iNO, ECMO availability, delayed surgical repair, multidisciplinary follow-up) is 70 to 80 percent. Prognosis is worse with earlier presentation (in the first hour of life), low o/e LHR, liver-up position, right-sided defect, large defect requiring patch repair, associated anomalies (chromosomal or major cardiac), and the need for ECMO. Long-term complications are common — persistent pulmonary hypertension (may require sildenafil for months), chronic lung disease with need for supplemental oxygen and diuretics, gastro-oesophageal reflux (needs medical therapy or fundoplication in 20 to 30 percent), failure to thrive with need for gastrostomy feeding, hearing loss (often sensorineural, related to hypoxia and ECMO), neurodevelopmental delay, chest wall deformities (pectus, scoliosis) and recurrence of the hernia particularly after patch repair. A multidisciplinary CDH follow-up clinic (paediatric surgery, pulmonology, cardiology, gastroenterology, audiology, physiotherapy, developmental paediatrics) is the standard of care through school age and beyond. Compare hiatal hernia which is a different adult condition with reflux management and antireflux surgery.
This content is for educational purposes for NEET PG exam preparation. It is not a substitute for professional medical advice, diagnosis, or treatment. Clinical information has been reviewed by qualified medical professionals.
Written by: NEETPGAI Editorial Team
Reviewed by: Pending SME Review
Last reviewed: September 2026
