Congenital Diaphragmatic Hernia (CDH)

What happens in CDH

The diaphragm forms between weeks 4 and 12 of pregnancy. If it fails to close completely, abdominal organs slide into the chest as they grow. The lungs on that side, and often the other side too, have less room to develop. They have fewer airways and air sacs, and their blood vessels are thick-walled and narrow, causing pulmonary hypertension (high pressure in the lung arteries) after birth.

Types

Left-sided CDH is most common. Right-sided CDH often involves the liver and can be more severe.

Causes

The cause is usually unknown. About 30% to 40% of babies with CDH have other birth defects, especially heart defects, or a chromosomal or genetic condition (such as trisomy 18 or 13, or other syndromes). Isolated CDH rarely recurs in families.

Diagnosis during pregnancy

Most cases are found on the routine anatomy ultrasound at 18 to 22 weeks, showing the stomach or bowel in the chest and the heart pushed aside. Specialist centers then use:

• lung-to-head ratio (observed/expected LHR): estimates lung size and predicts severity
• liver position: liver in the chest suggests more severe disease
• fetal MRI: measures lung volume more precisely
• fetal echocardiogram: checks the heart
• genetic testing by amniocentesis

This information guides counseling, delivery planning and eligibility for fetal treatment.

Fetal treatment: FETO

Fetoscopic endoluminal tracheal occlusion (FETO) places a small balloon in the baby's windpipe through a thin scope at around 27 to 30 weeks. Blocking the windpipe traps lung fluid, which stretches and grows the lungs. The balloon is removed before birth. Trials have shown improved survival in severe left-sided CDH, though FETO increases the risk of preterm birth. It is offered only at specialized centers for selected cases.

Signs after birth

Babies not diagnosed before birth usually show symptoms within hours:

• severe breathing difficulty and fast breathing
• blue color (cyanosis)
• a sunken (scaphoid) abdomen, because organs are in the chest
• a barrel-shaped chest
• reduced breath sounds on one side, sometimes bowel sounds in the chest

A chest X-ray confirms the diagnosis. Some milder cases (see diaphragmatic hernia), especially Morgagni hernias, are found later in childhood or adulthood with recurrent chest infections, vomiting or abdominal pain.

Treatment after birth

Stabilization

• delivery at a center with neonatal surgery, pediatric surgeons and ECMO capability
• immediate intubation and gentle ventilation, avoiding bag-mask breathing, which inflates the bowel in the chest
• a tube into the stomach to decompress the bowel
• medicines to support blood pressure and treat pulmonary hypertension, such as inhaled nitric oxide
• ECMO (extracorporeal membrane oxygenation): a heart-lung bypass machine for babies who cannot be supported by ventilation alone

Surgery

The hernia is repaired once the baby is stable, usually days after birth. The surgeon moves the organs back into the abdomen and closes the hole with stitches or, for large defects, a patch. Some repairs are done using minimally invasive techniques.

Long-term outlook and complications

Survival for isolated CDH at experienced centers is often reported at 70% to 90%, varying with severity, lung size, liver position, associated defects and need for ECMO.

Survivors may have:

• chronic lung disease and asthma-like symptoms
• persistent pulmonary hypertension
• gastroesophageal reflux and feeding difficulties, sometimes needing a feeding tube
• slow growth
• hernia recurrence, especially with patch repairs
• chest wall deformities and scoliosis
• hearing loss
• developmental delays

Many children with CDH grow up to lead active lives. Multidisciplinary follow-up clinics monitor lungs, growth, nutrition, development and hearing through childhood.

Frequently asked questions

What causes congenital diaphragmatic hernia?

In most cases the cause is unknown. The diaphragm fails to close during early pregnancy. About a third of babies with CDH have other birth defects or genetic conditions. Isolated CDH does not usually run in families.

What is the survival rate for congenital diaphragmatic hernia?

Survival for isolated CDH at experienced specialist centers is often 70% to 90%, depending on severity. Small lung size, liver in the chest, right-sided defects and other birth defects lower survival. Your fetal care team can give a personalized estimate.

Can CDH be treated before birth?

In selected severe cases, a procedure called FETO places a balloon in the baby's windpipe during pregnancy to help the lungs grow. It is offered at specialized fetal therapy centers. Most babies are treated after birth with intensive care and surgery.

How is CDH repaired?

After the baby is stabilized, a surgeon returns the organs to the abdomen and closes the hole with stitches or a patch. The timing depends on how stable the baby's breathing and blood pressure are.

What problems can children have after CDH repair?

They may have lung problems, reflux, feeding difficulties, slow growth, hernia recurrence, chest wall or spine shape changes, hearing loss or developmental delays. Regular follow-up in a specialist clinic helps identify and treat these early.