Congenital diaphragmatic hernia

Congenital diaphragmatic hernia occurs when the diaphragm fails to form a complete barrier between the thorax and the abdomen, leading to abdominal organs such as the bowel and stomach herniating into the thoracic cavity.

• Patients with congenital diaphragmatic hernia (CDH) will present with abdominal viscera visible in the thorax.
• Bowel, stomach and/or liver and spleen can also be present in the thorax.
• CDH often causes deviation of the heart from its normal position, and can cause pulmonary hypoplasia due to compression from abdominal viscera.
• In 80% of cases the anomaly is left-sided, and in 15% of cases it is right-sided. A small number of cases (5%) are either anterior or posterolateral.
• CDH can be identified on routine antenatal scanning, though many cases are diagnosed later in pregnancy or, rarely, after birth (following the development of polyhydramnios in the third trimester).

Around 20% of cases of CDH are associated with chromosomal anomalies, most commonly trisomy 13, trisomy 18 and Pallister-Killian syndrome.

Around 10% of cases are associated with other genetic syndromes. The most common of these is Fryns syndrome, an autosomal recessive condition that also presents anophthalmia, facial cleft, micrognathia and ventriculomegaly.

Recurrence risk is dependent on the underlying genetic or chromosomal cause. If no underlying cause is identified, and the case is found to be an isolated CDH, there is unlikely to be an increased risk in subsequent pregnancies.

If the case is associated with aneuploidy, the recurrence risk is around 1%.

If the case is associated with a recessive genetic syndrome, there is a 25% recurrence risk – but this would depend on the specific syndrome, and individualised counselling from the clinical genetics team would be recommended.

Antenatal management

Management options for patients who have a baby diagnosed with CDH are listed below.

• The case should be referred to fetal medicine for confirmation of diagnosis, followed by counselling regarding the nature of the condition and expected antenatal and postnatal management. The severity and subsequent predicted prognosis need to be explained, and termination of pregnancy discussed.
• A detailed ultrasound and fetal echocardiogram should be performed to assess for other anomalies as well as the severity of the CDH (which is most commonly done using the observed to expected lung-to-head ratio).
• Amniocentesis for QF-PCR and microarray should be offered.
• There should be a discussion regarding the option of a fetal MRI for further assessment of the problem and to help predict the prognosis.
• Some pregnancies may be considered for in utero treatment using ultrasound and fetoscopic guided tracheal occlusion. The fetal medicine team should assess whether the patient meets the eligibility criteria for this and refer to the subspecialist centres if appropriate.
• Four-weekly growth scans are recommended to monitor lung volume and assess for polyhydramnios. In some instances, an amnioreduction procedure may be offered for maternal symptoms relating to polyhydramnios.
• A third-trimester scan and appointment in a joint fetal medicine and neonatal surgical clinic is recommended to discuss postnatal surgical management.
• Delivery is recommended at a tertiary centre owing to the presence of onsite neonatal and surgical teams. Aim to deliver at around 38 to 39 weeks and anticipate vaginal birth unless other obstetric indications are present.

Postnatal management

Postnatal management options for patients with CDH are listed below.

• Surgical repair is required, which usually takes place a few days after delivery. Babies will then require a stay in the paediatric intensive care unit while being weaned from ventilation.
• Families should be offered genomic counselling if there is a recurrence risk, depending on whether a genetic cause is found.
• Where the fetus/baby does not survive, information from an autopsy may help direct further testing, unless a genomic cause has been identified already.

For clinicians

• Fetal Medicine Foundation: Diaphragmatic hernia
• NHS England: National Genomic Test Directory
• Online Mendelian Inheritance in Man (OMIM): % 229850 and # 601803

References:

• Russo FM, Cordier AG, De Catte L and others. ‘Proposal for standardized prenatal ultrasound assessment of the fetus with congenital diaphragmatic hernia by the European reference network on rare inherited and congenital anomalies (ERNICA)‘. Workstream Prenatal Management, ERNICA European reference network; Prenatal Diagnosis 2018: volume 38, issue 9, pages 629–637. DOI: 10.1002/pd.5297.

For patients

• CDH UK: Ongoing support
• Gov.uk: CDH: Information for parents