Fetal abnormalities » Thorax
Congenital pulmonary airway malformation
- 1 in 4,000 births.
- Hyperechogenic tumor in the fetal chest, usually presenting at >16 weeks’ gestation. Divided into solid or microcystic, macrocystic with one or more large cysts (>2 cm) and mixed with areas that are solid intermixed with areas containing multiple cysts <2 cm in diameter.
- The lesion is unilateral in >95% of cases and usually involves one lobe or segment of the lung.
- Hydrops is found in <10% of cases.
- Polyhydramnios, due to compressed and obstructed esophagus, may present at >26 weeks’ gestation.
- The incidence of chromosomal abnormalities and genetic syndromes is not increased.
- Defects in other systems, mainly cardiac, renal and tracheo-esophageal fistulas, are found in 10% of cases.
- Thoraco-amniotic shunting may be useful in cases of a large cyst causing major mediastinal shift and / or ascites.
- In a few cases of hydrops open fetal surgery with excision of the lesion has been carried out with relatively good results.
- There is some evidence that maternal administration of steroids may cause shrinkage of the lesion and resolution of hydrops.
- Ultrasound scans every 4 weeks to monitor growth, lung lesion and amniotic fluid volume.
- During the early third trimester >80% of the microcystic lesions resolve, but in >80% of these cases this is not a true resolution but purely inability to detect the lesion by ultrasound because the normal lungs also become echogenic. The lesion can be detected postnatally by chest X-ray or even better by CT scan.
- Place: hospital with neonatal intensive care and pediatric surgery.
- Time: 38 weeks. Earlier if there is evidence of poor growth, fetal hypoxia or hydrops.
- Method: induction of labor aiming for vaginal delivery.
- No hydrops: survival >95%.
- Hydrops: usually lethal.
- No increased risk of recurrence.