**4.1. Definition and incidence**

**3.3. Prognosis**

hydrops, the prognosis is poor (**Figure 12**).

**Figure 12.** Fetal hydrops and BPS: arrow—BPS mass, star—hydrothorax.

**Figure 11.** Differential diagnosis CCAM versus BPS.

174 Congenital Anomalies - From the Embryo to the Neonate

**3.4. Prenatal management**

The prognosis of BPS is favorable in the absence of other associated abnormalities. In many case series it was found that, similar to CCAM evolution and in BPS cases, there is often present a regression of the lesion [18, 19]. However, in fetuses with BPS associated with fetal

Fetal hydrops occurs only if a tension hydrothorax develops. The cause of unilateral hydrothorax associated with BPS is not well-defined. The torsion of a vascular pedicle or abnormal pressure gradient between the systemic artery and the pulmonary vein may be the cause [19]. Regardless the etiology, the persistence of the hydrothorax causes pulmonary compression with pulmonary

In isolated BPS karyotyping is not mandatory, but it is recommended if any other abnormality is associated. Fetal MRI may be useful for differential diagnosis. The family may choose to terminate the pregnancy if the diagnosis is established before 24 weeks and it is associated with other abnormalities such as: esophageal atresia, neurenteric cyst, CDH, pulmonary hypoplasia, cardiac

hypoplasia and the impairment of the caval venous drainage due to mediastinal shift.

Congenital pulmonary hypoplasia consists of the lowering of the lung volume in comparison to the lung volume corresponding to the gestational age. The causes of pulmonary hypoplasia are represented by: congenital diaphragmatic hernia (CDH), oligohydramnios, skeletal dysplasia, chest tumors, neuromuscular disorders that obstruct fetal respiratory movements. A rare cause is represented by the obstructive cardiac abnormalities of the right-sided heart, which may be accompanied either by the absence of the development of a single lung or the absence of the development of both lungs. Regardless the mechanism, pulmonary hypoplasia is responsible for the neonatal mortality, of 10–15% [23]. Pulmonary agenesis can be classified into three groups [23, 24]: in group 1, there are bronchial and lung agenesis, in group 2 there is a rudimentary bronchus without bronchial tissue and in group 3 it is a bronchial hypoplasia and a hypoplasia of lung tissue. Pulmonary agenesis is usually unilateral, and occurs at 4 weeks of gestation. The etiology of this anomaly is unknown. The incidence of pulmonary agenesis, either unilateral or bilateral, is very low, 0.0097% or 1 at 10,000 pregnancy [22]. More than half of the fetuses with pulmonary agenesis have other associated abnormalities: gastrointestinal, cardiovascular and genitourinary. Unilateral pulmonary agenesis may be associated with numerous other abnormalities: patent ductus arteriosus (PDA), atrial and ventricular septal defects, anomalous pulmonary venous drainage, tracheoesophageal fistula and duodenal atresia, hemivertebrae with scoliosis, facial abnormalities and limb abnormalities.
