**2.9. Differential diagnosis**

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

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

*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

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

• Left-sided CHD: stomach is in thorax seen in *four-chamber view*, almost half of the cases have liver herniation. • Right-sided CHD: almost always have liver herniation which is difficult to see; diagnosis is suspected in case of

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

left mediastinal shift and Doppler reveals abnormal course of hepatic vessels.

hernia should help distinguish it from a right-sided intrapleural hernia.

mass having the appearance of the liver or stomach is detected.

(**Figure 9**).

from mediastinal hernias (**Table 6**).

198 Congenital Anomalies - From the Embryo to the Neonate

• Thoracic mass with mediastinal shift.

S—stomach.

**Table 6.** Key sonographic features.

• Polyhydramnios secondary to esophageal compression.

*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 compress the esophagus and/or trachea.

*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 production.

*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 [27, 28].

*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, ganglioneuroma, pheochromocytoma, and neuroblastoma.

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

*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.
