Fetal Thoracic Imaging - Clinical Tree

Congenital Diaphragmatic Hernia

Definition

Congenital diaphragmatic hernia (CDH) refers to an embryologic defect in the diaphragm resulting in variable degrees of herniation of abdominal contents into the thoracic cavity.

Incidence and Pathogenesis

Incidence is 2.4:10,000 to 4.9:10,000. Most are sporadic. Incidence may be increasing, suggesting the effect of environmental/nutritional exposures.
75% left-sided, 15% right-sided, 10% bilateral; in fetal demises, 47% left-sided, 27% right-sided, 27% bilateral.
Results from abnormal diaphragm development at 6–10 weeks with incomplete closure of the pleuroperitoneal folds.
Associated with smoking, alcohol, vitamin A deficiency, thalidomide, anticonvulsants.
Herniated viscera cause decreased bronchial branching, alveolar number, pulmonary vascularization, and overmuscularization of pulmonary arterial tree, leading to pulmonary hypoplasia, pulmonary hypertension.

Key Diagnostic Features

Major finding is a thoracic mass accompanied by mediastinal shift.
Left-sided CDH
- Stomach appears as a cystic thoracic mass and is not seen in its normal position.
- Liver is herniated in 50%.
In almost all right-sided CDHs, the liver herniates; liver and lung have similar echogenicities, so a discrete mass is not always seen; diagnosis is suspected because of a mediastinal shift to the left.
- Color Doppler ultrasound can show hepatic vascularity; gallbladder may be seen.
- The use of MRI is increasing, especially for the diagnosis of liver herniation, where it is an important prognostic indicator.
Abdominal circumference may be small, and the abdomen may appear scaphoid.
Polyhydramnios results from esophageal compression; hydrops may follow.
Depending on size of defect, herniated contents may change position over time.

Differential Diagnosis

Cystic lesions of the lung, specifically congenital pulmonary airway malformation (CPAM), especially types 1 and 2; and bronchopulmonary sequestration.
In left-sided congenital diaphragmatic hernia (CDH): bronchogenic cyst.
In right-sided CDH: type 3 CPAM.
Mediastinal teratomas tend to be more vascular, and the abdominal contents are in situ.
In CDH, the mass is commonly made up of intestines, and prolonged imaging may allow visualization of peristalsis.

Associated Anomalies

Has been associated with an increased nuchal translucency in the first trimester.
Associated anomalies in 40%–60% of liveborn infants (complex CDH or CDH positive), and in 95% of cases of intrauterine fetal demise.
Cardiac anomalies in 40%, most commonly ventricular septal defects and atrial septal defects.
Gastrointestinal anomalies second most common, including Meckel diverticulum and anal atresia.
Chromosome anomalies in 10%–20%, most commonly trisomy 21, trisomy 18, and trisomy 13.
Syndromic etiology in 10%.

Imaging

Figure 22.1, Congenital diaphragmatic hernia.

Figure 22.2, Left-sided congenital diaphragmatic hernia.

Figure 22.3, Left-sided congenital diaphragmatic hernia.

Figure 22.4, Left-sided congenital diaphragmatic hernia (CDH).

Figure 22.5, Fetus with multiple anomalies associated with congenital diaphragmatic hernia.

Figure 22.6, Left-sided congenital diaphragmatic hernia (CDH).

Management

Antenatal Monitoring

Detailed ultrasound and fetal echocardiogram. Ultrafast fetal MRI use is increasing, especially to assess liver herniation.
Karyotype, array comparative genomic hybridization (microarray); consider whole exome or genome screening if multiple anomalies present.
Consultation with departments of genetics, neonatology, and pediatric surgery.
Most important prognostic signs are liver herniation, right-sided lesion, and fetal lung volume as assessed by the lung area–to–head circumference ratio (LHR). ^, The LHR may be correlated to gestational age using the observed/expected LHR; calculators are available online ( https://www.perinatology.com/calculators/LHR.htm ).
Serial ultrasounds for growth, amniotic fluid, size, and quality of the intestine.
Antenatal testing started at 32–33 weeks’ gestation, or earlier if severe.

Obstetric Management

When gestation is less than 24 weeks, termination of pregnancy can be considered.
With abnormal testing, especially after 34 weeks, delivery should be strongly considered.
Antenatal steroids if less than 34 weeks; giving steroids at greater than 34 weeks has not been associated with improved outcomes.
Delivery is recommended at a tertiary care facility with extracorporeal membrane oxygenation (ECMO) capabilities.
Cesarean delivery is reserved for usual obstetric indications.
Fetal endoscopic tracheal occlusion (FETO) typically achieved through the use of an endoscopic balloon is available as an investigational intervention in the United States. The procedure has typically been reserved for fetuses with poor prognosis as predicted by the O/E LHR. FETO has been associated with improvement in survival, though with a higher risk of preterm delivery, usually due to preterm prelabor rupture of the membranes. ^, Maternal complications associated with FETO occur in 1%–7% of cases. Recent studies suggest that as the procedure becomes more common, its risk profile has improved. Centers available for FETO may be accessed through naftnet.org .

Neonatal Management

ECMO is frequently used, although the literature is inconclusive about its effect on survival. Pulmonary hypertension may require vasodilator therapy.
Management ultimately involves reduction of the herniated viscera and surgical repair of the diaphragmatic defect, which is usually delayed until the newborn is clinically stable.
Traditional repair was via an open surgical approach, but minimally invasive techniques have been introduced.

Prognosis

Spontaneous intrauterine fetal demise occurs in 2%.
Among fetuses who survive to delivery, survival of those with isolated CDH is 60%–80%.
Survival is improved in prenatally diagnosed infants and infants born at a tertiary care facility.
Prognosis is associated with gestational age, so preterm birth should be avoided if possible.
Worse outcomes are seen in Blacks, other minorities, and those with public insurance.
Long-term complications in pulmonary, musculoskeletal, gastrointestinal, and neurodevelopmental systems in 20%–30%.

Key Points

CDH involves herniation of abdominal contents through the diaphragm into the thoracic cavity; adverse outcomes are usually related to pulmonary complications (hypoplasia).
Major ultrasound finding is a thoracic mass accompanied by mediastinal shift.
Evaluation includes genetic testing, fetal echocardiography, serial ultrasound, and, increasingly, MRI.
In utero therapy using FETO is becoming more common. An ongoing US trial is underway.
Delivery should occur at a tertiary care facility with availability of ECMO and should occur at term unless otherwise indicated.

Cystic Lung Lesions, Congenital Pulmonary Airway Malformation, and Bronchopulmonary Sequestration

Definition

The most common cystic lung lesions include congenital pulmonary airway malformation (CPAM) and the bronchopulmonary sequestration (BPS). CPAMs are hamartomatous lesions composed of the different elements of the respiratory tract and are connected to that tract. BPS is composed of nonfunctioning respiratory tract tissue and does not connect with the respiratory tract.

Incidence and Pathogenesis

The incidence of congenital pulmonary airway malformation (CPAM), also known as congenital cystic adenomatoid malformation (CCAM), ranges from 1:11,000 to 1:35,000 live births; midtrimester incidence is higher because of spontaneous resolution. ^, Bronchopulmonary sequestration (BPS) is even more rare.
Both develop during the pseudoglandular phase of lung development (7–17 weeks’ gestation); they may have common origin.
CPAM is a hamartomatous lesion containing tissue from different pulmonary origins.
BPS involves extraneous, nonfunctioning lung tissue that has separated from the normal pulmonary structure.
Both have oncogenic potential.
Hybrid lesions exist.

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