# Congenital Diaphragmatic Hernia

> Congenital diaphragmatic hernia for NEET-PG Paediatrics: Bochdalek presentation, scaphoid abdomen, pulmonary hypoplasia and why bag-mask ventilation is avoided.

- Canonical URL: https://prepelephant.com/topics/neet-pg/paediatrics/congenital-diaphragmatic-hernia
- Exam / course: NEET-PG · Subject: Paediatrics
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-14
- Last updated: 2026-10-14
- Reference basis: Nelson Textbook of Pediatrics; Avery's Diseases of the Newborn; Rudolph's Pediatrics
- How to cite: "Congenital Diaphragmatic Hernia", PrepElephant, https://prepelephant.com/topics/neet-pg/paediatrics/congenital-diaphragmatic-hernia

## Direct answer

Congenital diaphragmatic hernia is a defect in the diaphragm that lets abdominal organs enter the chest, most often through the posterolateral Bochdalek defect on the left. The herniated viscera impair lung growth, producing pulmonary hypoplasia and persistent pulmonary hypertension at birth. Management avoids bag-mask ventilation, uses gentle intubated ventilation and times surgical repair after the baby is stabilised.

## What you must remember

- **Bochdalek hernia:** a posterolateral defect that accounts for most cases, most commonly on the left side.
- **Presentation:** respiratory distress soon after birth, a scaphoid abdomen, bowel sounds in the chest and a displaced apex beat.
- **Pulmonary hypoplasia:** reduced lung volume and vascular growth on both sides, which is the main determinant of outcome.
- **Pulmonary hypertension:** persistent pulmonary hypertension of the newborn causes right-to-left shunting and severe hypoxia.
- **Ventilation:** avoid bag-mask ventilation, since gas in the bowel inside the chest worsens lung compression.
- **Prenatal diagnosis:** ultrasound may show bowel in the chest, and measures of lung size are used to estimate severity.
- **Definitive care:** surgical repair after stabilisation, with ECMO reserved for refractory hypoxia.

## A stabilisation sequence at delivery

The priority in congenital diaphragmatic hernia is to protect whatever lung is present, so the sequence below is designed to avoid worsening hypoplasia. The steps reflect the usual approach on neonatal units, though the exact settings and thresholds are set locally.

1. **Intubate at birth:** secure the airway promptly with an endotracheal tube rather than using bag-mask ventilation, which distends the bowel in the chest.
2. **Decompress the stomach:** place an orogastric tube to vent the stomach and reduce further pressure on the lungs.
3. **Ventilate gently:** use relatively low peak pressures and accept modest hypercapnia to limit barotrauma.
4. **Manage pulmonary hypertension:** compare pre- and post-ductal saturations and treat with ventilation, sedation and inhaled nitric oxide as needed.
5. **Stabilise before surgery:** correct acidosis, hypotension and hypoxia, and time the repair once the baby is stable, often within days rather than immediately.
6. **Consider ECMO:** for refractory hypoxia or hypotension despite optimal ventilation, extracorporeal support is an option in suitable centres.

## Where the exam tries to catch you

Congenital diaphragmatic hernia questions test the first steps at birth, the imaging appearance and the logic of timing surgery.

- **Trap:** starting with bag-mask ventilation. — **Correct:** bag-mask ventilation inflates the bowel in the chest and worsens lung compression, so intubation with gentle ventilation is preferred.
- **Trap:** reading the chest X-ray as a pneumothorax. — **Correct:** the classic film shows bowel loops in the left hemithorax with mediastinal shift, and a nasogastric tube may coil in the chest.
- **Trap:** operating immediately at birth. — **Correct:** repair is timed after stabilisation, since rushing surgery in an unstable baby worsens the outcome.

## Frequently asked questions

### Why is bag-mask ventilation avoided in congenital diaphragmatic hernia?

Bag-mask ventilation is avoided in congenital diaphragmatic hernia because it inflates the stomach and bowel, which lie in the chest, and worsens lung compression. Gas-filled bowel also shifts the mediastinum and aggravates hypoplasia. Early endotracheal intubation with gentle ventilation is therefore preferred.

### What is the Bochdalek hernia?

The Bochdalek hernia is the posterolateral diaphragmatic defect that accounts for most congenital diaphragmatic hernias. It is most often on the left side, allowing abdominal organs to enter the left hemithorax. It is the most common type of congenital diaphragmatic hernia seen in neonatal practice.

### Why does congenital diaphragmatic hernia cause pulmonary hypertension?

Congenital diaphragmatic hernia causes pulmonary hypertension because the herniated viscera impair lung growth, leaving hypoplastic lungs with abnormal pulmonary vasculature. This raises pulmonary vascular resistance and produces right-to-left shunting through the foramen ovale and ductus arteriosus. Persistent pulmonary hypertension is a major cause of early death in these babies.

### What does the chest X-ray show in congenital diaphragmatic hernia?

The chest X-ray in congenital diaphragmatic hernia typically shows bowel loops in the affected hemithorax with a shifted mediastinum. A nasogastric tube may coil in the chest, which supports the diagnosis. The appearance can be mistaken for pneumothorax, so the bowel loops should be recognised.