Prevalence:

• 1 in 4,000 births.

Ultrasound diagnosis:

• Abdominal viscera herniated into the thorax through defect in the diaphragm with associated deviation of the heart from its normal position.
• Bowel, stomach and / or liver in the thorax.
• Left (80%), right (15%) and posterolateral or anterior retrosternal (5%).
• Polyhydramnios at >26 weeks in most cases.

Associated abnormalities:

• Chromosomal defects, mainly trisomies 18 or 13 and occasionally tetrasomy 12p or Pallister–Killian syndrome, are found in 20% of cases.
• Genetic syndromes are found in 10% of cases. The most common is Fryns syndrome (autosomal recessive; anophthalmia, facial cleft, micrognathia, ventriculomegaly, diaphragmatic hernia).
• Defects in other systems, mainly craniofacial and cardiac, are found in 20% of cases.

Investigations:

• Detailed ultrasound examination, including echocardiography.
• Amniocentesis for karyotyping (CVS not appropriate for Pallister–Killian syndrome) and array.
• Assessment of severity is by measurement of contralateral lung area in a transverse section of the chest to head circumference ratio (LHR). The measured LHR is compared to the LHR in normal babies and the disease is classified as severe if the ratio is <25%, moderate if 26-45% and mild if >45%.
• Ultrafast MRI may be useful for accurate assessment of the proportion of the liver found in the thorax.

Fetal therapy:

• FETO (fetoscopic endoluminal tracheal occlusion). This involves the endoscopic insertion of an inflatable balloon into the trachea with consequent retention of fluid produced by the lungs which may stimulate lung growth. The balloon is inserted at 26 weeks’ gestation and removed endoscopically at 34 weeks.
• An international randomized study is investigating the effectiveness of FETO, compared to expectant management, in reducing mortality and morbidity.

Follow up:

• Ultrasound scans every 4 weeks to monitor lung growth and amniotic fluid volume. Amniodrainage may be necessary if there is polyhydramnios and cervical shortening.
• Risk of fetal death about 5%.

Delivery:

• Place: hospital with neonatal intensive care and pediatric surgery.
• Time: 38 weeks. Earlier if there is evidence of poor growth or fetal hypoxia.
• Method: induction of labor aiming for vaginal delivery.

Prognosis:

• Part of trisomy 18: lethal.
• Isolated: survival is <15% for severe disease, 50% for moderate disease and >90% for mild disease.
• Morbidity in survivors includes developmental delay in up to 30% of cases (especially in those requiring ECMO), gastro-esophageal reflux in 50% of cases, and scoliosis in 10% of cases.

Recurrence:

• Isolated: no increased risk.
• Part of trisomies: 1%.
• Part of syndromes: 25%.