**2.7. Associated anomalies**

The most common associated anomalies are cardiovascular in 40–60% of live-born infants and in 95% of fetal demise; therefore, a detailed ultrasound examination must be performed in every case diagnosed with CDH [19] (**Table 5**).

### **2.8. Ultrasound diagnosis**

Ultrasound evaluation of the thorax can be carried out easily until 25–26 weeks of gestation; after this period, the increased mineralization of the ribs limits the display of intrathoracic organs, especially for coronal or sagittal views. A number of thoracic anomalies evolve; they can appear only in the third trimester or they can regress before birth. Therefore, if an initial assessment of the thorax can be performed as early as at the 12th week of gestation, in order to follow up abnormal cases, late third-trimester scans may be needed.

*Scanning planes*: the most important view for the assessment of intrathoracic anatomy is the classic *four chamber view* of the fetal heart. In this plane, most thoracic viscera can be visualized, including the ribs, the sternum, and the cutaneous outline. The *midsagittal* and *parasagittal views* allow display of the diaphragm as a hypoechoic line below the lungs and the heart and above the liver and the stomach. The diaphragm shows a curved outline, convex toward the thorax.


**Table 5.** Asociated anomalies.

*Axial four-chamber view*: the following structures should be checked: the two lungs appear as solid, homogeneous; weakly hyperechogenic that almost completely surrounds the heart, right larger than left lung; thoracic aorta behind the left atrium; the heart oriented toward the left; the ribs and overlaying cutaneous tissue; and posterior, the spine (**Figure 2**).

*Three-vessel view*: allows visualization of the thymus and its relationship with the great vessels and appears as a well-defined roundish solid structure interposed between the great vessels and the sternum. It is weakly hypoechogenic in comparison with the surrounding lungs. In front of the spine and behind the three vessels, the trachea, and, with some difficulty, the esophagus can be seen (**Figure 3**).

*Midsagittal view*: does not give significant information regarding the lungs because it is occupied mainly by the heart.

*Right parasagittal view*: the diaphragmatic hypoechogenic layer can be seen below the right lung.

*Left parasagittal view*: the diaphragmatic hypoechogenic layer can be seen below the left lung and the heart and allows to demonstrate that the stomach is located below the diaphragm.

The ultrasound diagnosis of CDH is, in general, indirect: the abnormal intrathoracic position of the stomach and/or the other migrated viscera and the displacement of the heart and the mediastinum is detected (**Figure 4**).

*Left posterolateral CDH*: in the *four-chamber view*, the stomach is in the left hemithorax or in the mediastinum (**Figure 5**).

Frequently, a few small bowel loops can be visualized near the stomach, while the heart and the mediastinum are pushed contralaterally. Much more rarely, the spleen and/or the left liver lobe may migrate as well. In few cases, only some ileal loops and/or the left hepatic

lobe migrate into the thorax; therefore, the diagnosis is based only on dextrocardia and the

**Figure 4.** Sagittal view. Note the different echogenicity between lungs and abdominal viscera. Diaphragm appears as a

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Kinking of the sinus venosus is a reliable sign in case of herniated left liver lobe; the bowing of the umbilical segment of the portal vein (portal sinuses) to the left of the midline and coursing of portal vessels to the lateral segment of the left hepatic lobe toward or above the diaphragm

It must be kept in mind that even though the diaphragmatic defect occurs in the first trimester, the visceral herniation is variable in time, from early second trimester to the first hour of life.

*The sagittal views allow* to detect some additional features that help confirm the diagnosis; the evidence of intrathoracic viscera on the four-chamber view is the basic requirement for a cor-

unusual inhomogeneous appearance of the left hemithorax (**Figure 6**).

**Figure 3.** Three-vessel view. Note the thymus slightly hypoechogenic than lungs.

is considered the best predictor for liver herniation [20] (**Figure 7**).

rect diagnosis of CDH.

hypoechogenic thin line.

**Figure 2.** Four chamber view.

**Figure 3.** Three-vessel view. Note the thymus slightly hypoechogenic than lungs.

*Axial four-chamber view*: the following structures should be checked: the two lungs appear as solid, homogeneous; weakly hyperechogenic that almost completely surrounds the heart, right larger than left lung; thoracic aorta behind the left atrium; the heart oriented toward the

*Three-vessel view*: allows visualization of the thymus and its relationship with the great vessels and appears as a well-defined roundish solid structure interposed between the great vessels and the sternum. It is weakly hypoechogenic in comparison with the surrounding lungs. In front of the spine and behind the three vessels, the trachea, and, with some difficulty, the

*Midsagittal view*: does not give significant information regarding the lungs because it is occu-

*Right parasagittal view*: the diaphragmatic hypoechogenic layer can be seen below the right lung. *Left parasagittal view*: the diaphragmatic hypoechogenic layer can be seen below the left lung and the heart and allows to demonstrate that the stomach is located below the diaphragm.

The ultrasound diagnosis of CDH is, in general, indirect: the abnormal intrathoracic position of the stomach and/or the other migrated viscera and the displacement of the heart and the

*Left posterolateral CDH*: in the *four-chamber view*, the stomach is in the left hemithorax or in the

Frequently, a few small bowel loops can be visualized near the stomach, while the heart and the mediastinum are pushed contralaterally. Much more rarely, the spleen and/or the left liver lobe may migrate as well. In few cases, only some ileal loops and/or the left hepatic

left; the ribs and overlaying cutaneous tissue; and posterior, the spine (**Figure 2**).

esophagus can be seen (**Figure 3**).

194 Congenital Anomalies - From the Embryo to the Neonate

mediastinum is detected (**Figure 4**).

pied mainly by the heart.

mediastinum (**Figure 5**).

**Figure 2.** Four chamber view.

**Figure 4.** Sagittal view. Note the different echogenicity between lungs and abdominal viscera. Diaphragm appears as a hypoechogenic thin line.

lobe migrate into the thorax; therefore, the diagnosis is based only on dextrocardia and the unusual inhomogeneous appearance of the left hemithorax (**Figure 6**).

Kinking of the sinus venosus is a reliable sign in case of herniated left liver lobe; the bowing of the umbilical segment of the portal vein (portal sinuses) to the left of the midline and coursing of portal vessels to the lateral segment of the left hepatic lobe toward or above the diaphragm is considered the best predictor for liver herniation [20] (**Figure 7**).

It must be kept in mind that even though the diaphragmatic defect occurs in the first trimester, the visceral herniation is variable in time, from early second trimester to the first hour of life.

*The sagittal views allow* to detect some additional features that help confirm the diagnosis; the evidence of intrathoracic viscera on the four-chamber view is the basic requirement for a correct diagnosis of CDH.

**Figure 5.** Left congenital diaphragmatic hernia. The stomach is in the left hemithorax and the heart is displaced to the right.

**Figure 6.** Left CDH. Herniation of left liver lobe and bowel loops. The heart is displaced to the right hemithorax.

*Right-sided CDH*: the diagnosis is difficult because the main feature, the intrathoracic displacement of the stomach, is absent because the defect is on the other side of the diaphragm. There are several indirect signs that lead to diagnosis. One is the leftward rotation of the heart with increase of the cardiac axis (**Figure 8**) and the upward displacement of the right hepatic lobe into the right hemithorax. This sign is best observed using color Doppler to identify the suprahepatic veins in the thorax because of the similar echogenicity of the lung and liver. Rightsided intrapleural hernias are less common, always contain liver, and may contain variable amounts of bowel and stomach. Rarely, intrapleural hernias may be bilateral; these tend to be associated with severe pulmonary hypoplasia. The midline position of the heart, the lack of

cardiomediastinal shift in cases of suspected intrapleural hernia should raise suspicion for the

**Figure 8.** Leftward rotation of the heart with increase of the cardiac axis and upward displacement of the right hepatic

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*Anterior and central CDH*: the ventral type appears anteriorly because of the central tendons' defect. The central tendon of the diaphragm on his upper surface and the pericardium are

presence of bilateral intrapleural hernias.

lobe into the right hemithorax.

**Figure 7.** Portal vessels extending into the thorax. Left liver lobe (markers).

**Figure 7.** Portal vessels extending into the thorax. Left liver lobe (markers).

*Right-sided CDH*: the diagnosis is difficult because the main feature, the intrathoracic displacement of the stomach, is absent because the defect is on the other side of the diaphragm. There are several indirect signs that lead to diagnosis. One is the leftward rotation of the heart with increase of the cardiac axis (**Figure 8**) and the upward displacement of the right hepatic lobe into the right hemithorax. This sign is best observed using color Doppler to identify the suprahepatic veins in the thorax because of the similar echogenicity of the lung and liver. Rightsided intrapleural hernias are less common, always contain liver, and may contain variable amounts of bowel and stomach. Rarely, intrapleural hernias may be bilateral; these tend to be associated with severe pulmonary hypoplasia. The midline position of the heart, the lack of

**Figure 5.** Left congenital diaphragmatic hernia. The stomach is in the left hemithorax and the heart is displaced to the right.

196 Congenital Anomalies - From the Embryo to the Neonate

**Figure 6.** Left CDH. Herniation of left liver lobe and bowel loops. The heart is displaced to the right hemithorax.

**Figure 8.** Leftward rotation of the heart with increase of the cardiac axis and upward displacement of the right hepatic lobe into the right hemithorax.

cardiomediastinal shift in cases of suspected intrapleural hernia should raise suspicion for the presence of bilateral intrapleural hernias.

*Anterior and central CDH*: the ventral type appears anteriorly because of the central tendons' defect. The central tendon of the diaphragm on his upper surface and the pericardium are communicating, if there is a defect at this site a pericardial effusion may develop. Ventral hernias may push the heart posteriorly but do not tend to cause pulmonary hypoplasia (**Figure 9**).

It was reported in a prospective study on 78,000 pregnancies at first trimester screening for chromosomal abnormalities by nuchal translucency thickness, 19 chromosomally normal fetuses with diagnosis of congenital diaphragmatic hernia. Only one of them was diagnosed in the first trimester; diagnosis was based on the visualization of the stomach in the thorax. In about one-third of the cases of diaphragmatic hernia, they found increased nuchal translucency. In the majority of the infants (83%) who died in the neonatal period due to pulmonary hypoplasia, nuchal translucency was increased, while the respective percentage for the survivors was 22%. The authors hypothesized that the accumulated nuchal fluid may be caused by venous congestion determined by intrathoracic compression due to early herniation of the

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The compression of herniated organs on esophagus or gastic outlet obstruction causes polyhydramnios which may became visible later in pregnancy. Another cause of polyhydramnios in cases with CDH is esophageal atresia with tracheoesophageal fistula, which may be very difficult to diagnose because the visualization of the proximal esophageal pouch is dependent

*Bronchogenic cysts* (*foregut duplication*) contain several components of the bronchi, including respiratory epithelia, mucous glands, and cartilage and may occur anywhere along the length of the trachea or esophagus [26]. Most are diagnosed incidentally or if large enough, can com-

*Congenital cystic adenomatoid malformation (CCAM)*: a developmental abnormality of the lung resulting from abnormal cell proliferation and decreased programmed cell death of lung tissue. Type I CCAM is most common and is distinguished by relatively large cysts and mucin

*Cystic teratomas* are benign tumors most often found in the anterior mediastinum. They consist of several differentiated cell types derived from endoderm, ectoderm, and/or mesoderm

*Neurogenic tumors* are the most common lesion found in the posterior mediastinum. They are likely to be of neural crest origin; the majority is benign: neurilemoma, neurofibroma, gan-

*Pulmonary agenesis* refers to partial or complete absence of lung tissue that is caused by failure

*Pulmonary sequestration* results from primitive lung tissue that is not connected to the tracheobronchial tree. Sequestration may be intrapulmonary, occurring within the pleura of the normal lung or extrapulmonary, occurring outside the normal lung within its own pleural sac.

The best validated measurement is contralateral lung area assessed by 2D ultrasound through the so-called lung area/head circumference ratio (LHR) [29]. Different methods for measuring were described but the most reproducible and accurate method involves tracing the lung contours.

abdominal organs [25].

**2.9. Differential diagnosis**

of lung bud development.

**2.10. Prognostic indicators**

production.

[27, 28].

press the esophagus and/or trachea.

on its being distended by swallowed amniotic fluid.

glioneuroma, pheochromocytoma, and neuroblastoma.

The smaller Morgagni hernia, usually is an isolated anterior defect and given its small size and location does not cause compression of thoracic organs. Morgagni hernias do not communicate with the pericardial space; therefore, this feature is a key element in differentiation from mediastinal hernias (**Table 6**).

*Hiatal CDH*: on ultrasound examination, it may appear as a hypoechogenic image behind the fetal heart in the posterior mediastinum, anterior to the vertebral body in continuity with a small fetal stomach located in the abdominal cavity just below the diaphragm in a median position. Parasagittal sonographic sections of the fetal thorax show an intact diaphragm on both sides. During the examination, stomach peristalsis may be visualized or the up and down movements of the stomach into the fetal thorax [21, 22]. The absence of liver in a hiatal hernia should help distinguish it from a right-sided intrapleural hernia.

The diagnosis of diaphragmatic hernia is rare during the first trimester. Early diagnosis has been associated with poor prognosis and the presence of additional defects [23, 24]. A diagnosis of CDH is suggestive if a displacement of the fetal heart in association with an intrathoracic mass having the appearance of the liver or stomach is detected.

**Figure 9.** Transverse view of the fetal thorax with an anechogenic mass behind the heart; FH—fetal heart; Ao—aorta; S—stomach.


**Table 6.** Key sonographic features.

It was reported in a prospective study on 78,000 pregnancies at first trimester screening for chromosomal abnormalities by nuchal translucency thickness, 19 chromosomally normal fetuses with diagnosis of congenital diaphragmatic hernia. Only one of them was diagnosed in the first trimester; diagnosis was based on the visualization of the stomach in the thorax. In about one-third of the cases of diaphragmatic hernia, they found increased nuchal translucency. In the majority of the infants (83%) who died in the neonatal period due to pulmonary hypoplasia, nuchal translucency was increased, while the respective percentage for the survivors was 22%. The authors hypothesized that the accumulated nuchal fluid may be caused by venous congestion determined by intrathoracic compression due to early herniation of the abdominal organs [25].

The compression of herniated organs on esophagus or gastic outlet obstruction causes polyhydramnios which may became visible later in pregnancy. Another cause of polyhydramnios in cases with CDH is esophageal atresia with tracheoesophageal fistula, which may be very difficult to diagnose because the visualization of the proximal esophageal pouch is dependent on its being distended by swallowed amniotic fluid.
