Thorax Flashcards
What are the fetal anomalies associated with the Thorax?
8 Bronchial Atresia Bronchogenic Cyst Congenital High Airway Obstruction Syndrome Congenital Pulmonary Airway Malformation Diaphragmatic Hernia Lung Agenesis-Hypoplasia Pleural Effusion Pulmonary Sequestration
Bronchial Atresia
Prevalence: 1 in 100,000 births.
Ultrasound: Enlarged hyperechogenic lung with dilated bronchial tree resulting in mediastinal shift to the contralateral side.
Presence of ascites (resulting from central venous compression) is a bad prognostic factor.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndromes is not increased.
Follow up: Ultrasound scans every 4 weeks to monitor the evolution of the condition.
Prognosis: High rate of perinatal mortality.
Recurrence: No increased risk of recurrence.
Congenital High Airway Obstruction Syndrome
Prevalence: 1 in 50,000 births.
Ultrasound: Agenesis or stenosis of a segment of the upper airways at the level of the trachea or larynx. In a few cases the condition results from the presence of laryngeal cysts or laryngeal web.
Ultrasound features become evident ≥16 weeks’ gestation. The lungs are massively enlarged and hyperechogenic resulting in compression of the heart and development of ascites. The bronchial tree is dilated and the diaphragm inverted.
Assoc abnorm: The incidence of chromosomal abnormalities is not increased.
Genetic syndromes are found in >50% of cases. The most common is Fraser syndrome (autosomal recessive; microphthalmia, facial cleft, tracheal atresia, bilateral renal agenesis, heart defects, syndactyly or polydactyly).
Follow up: If the pregnancy continues, serial scans should be carried out to define the best time for delivery based on evolution of hydrops.
Prognosis: Highly lethal condition with almost all cases dying in the neonatal period.
There are a few case reports of spontaneous resolution in utero, either because of dilatation of a stenotic segment between the larynx and the trachea or even development of a tracheoesophageal fistula with drainage of the bronchial fluid into the esophagus.
Recurrence: Isolated: no increased risk.
Fraser syndrome: 25%.
Congenital Pulmonary Airway Malformation
Prevalence: 1 in 4,000 births.
Ultrasound: 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.
Assoc abnorm: 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.
Follow up: 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.
Prognosis: No hydrops: survival >95%.
Hydrops: usually lethal.
Recurrence: No increased risk of recurrence.
Diaphragmatic Hernia
Prevalence: 1 in 4,000 births.
Ultrasound: Abdominal viscera herniated into the thorax through defect in the diaphragm with associated deviation of the heart from its normal position.
Bowel, stomach and / or liver in the thorax.
Left (80%), right (15%) and posterolateral or anterior retrosternal (5%).
Polyhydramnios at >26 weeks in most cases.
Assoc abnorm: Chromosomal defects, mainly trisomies 18 or 13 and occasionally tetrasomy 12p or Pallister–Killian syndrome, are found in 20% of cases.
Genetic syndromes are found in 10% of cases. The most common is Fryns syndrome (autosomal recessive; anophthalmia, facial cleft, micrognathia, ventriculomegaly, diaphragmatic hernia).
Defects in other systems, mainly craniofacial and cardiac, are found in 20% of cases.
Follow up: Ultrasound scans every 4 weeks to monitor lung growth and amniotic fluid volume. Amniodrainage may be necessary if there is polyhydramnios and cervical shortening.
Risk of fetal death about 5%.
Prognosis: Part of trisomy 18: lethal.
Isolated: survival is <15% for severe disease, 50% for moderate disease and >90% for mild disease.
Morbidity in survivors includes developmental delay in up to 30% of cases (especially in those requiring ECMO), gastro-esophageal reflux in 50% of cases, and scoliosis in 10% of cases.
Recurrence: Isolated: no increased risk.
Part of trisomies: 1%.
Part of syndromes: 25%.
Bronchogenic Cyst
Prevalence: 1 in 50,000 births.
Ultrasound: Single cyst in a central position with no signs of compression and no associated altered echogenicity of the adjacent lung.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndromes is not increased.
Follow up: Ultrasound scans every 4 weeks to monitor the evolution of the lesion.
Prognosis: The cysts are usually asymptomatic except in cases of tracheobronchial obstruction.
Recurrence: No increased risk of recurrence.
Lung Agenesis-Hypoplasia
Prevalence: 1 in 50,000 births.
Ultrasound: Complete absence or hypoplasia of one lung, usually the right one, with major mediastinal shift.
Assoc abnorm: The incidence of chromosomal abnormalities is not increased.
The association of hypoplastic right lung with hypoplastic right pulmonary artery and partial pulmonary venous drainage of the right lung into the inferior vena cava is referred to as Scimitar syndrome.
Follow up: Ultrasound scans every 4 weeks to monitor the evolution of the condition.
Prognosis: Prognosis is worse for right than left lung agenesis probably because of greater degree of heart and mediastinal displacement. In Scimitar syndrome, mortality is about 10% due to severe pulmonary hypertension.
Recurrence: No increased risk of recurrence.
Pulmonary Sequestration
Prevalence: 1 in 15,000 births
Ultrasound: Hyperechogenic mass in the lung, mostly in the left lower lobe.
Color Doppler demonstrates a feeding vessel that arises from the descending aorta.
In 75% of cases it is intralobar, making it indistinguishable in appearance from microcystic CPAM.
In 25% of cases it is extralobar, located outside the normal lung with its own visceral pleura; in most of these cases there is an associated pleural effusion.
Assoc abnorm: The incidence of chromosomal abnormalities and genetic syndromes is not increased.
Defects in other systems, mainly diaphragmatic hernia and cardiac or vertebral anomalies are found in up to 50% of cases with extralobar sequestration.
Follow up: Ultrasound scans every 4 weeks to monitor growth of the tumor and hydrothorax or hydrops.
In >30% of cases there is regression or disappearance of the tumor during the 3rd trimester.
Prognosis: Survival: >95%.
Postnatal therapy: endoscopic removal of mass or selective embolization of the feeding artery.
Recurrence: No increased risk of recurrence.
Pleural Effusion
Prevalence: Isolated congenital chylothorax is found in about 1 in 10,000 births.
Ultrasound: Usually presents with polyhydramnios at around 26 weeks’ gestation.
Unilateral (25% of cases) or bilateral anechoic area surrounding the lung. Subjectively classified as mild, moderate or severe and in the latter case if unilateral there is mediastinal shift.
In half of the cases the effusion is isolated and in the other half there is associated hydrops with skin oedema and / or ascites.
Assoc abnorm: Chromosomal defects, mainly trisomy 21 and monosomy X, are found in 10% of cases. Noonan syndrome (autosomal dominant but >90% are due to de novo mutations; cystic hygromas, hypertelorism, pulmonary stenosis, fetal growth restriction), is found in <5% of cases of isolated hydrothorax. In the case of associated hydrops there is a wide range of genetic conditions, especially if there are other defects.
Follow up: Ultrasound scans every 2 weeks to monitor the evolution of the pleural effusions and associated hydrops. Insertion of new shunts may become necessary if these are blocked or displaced.
Prognosis: Isolated effusion: survival is >90%.
Effusions with hydrops: in 50% of cases the hydrops resolves after thoraco-amniotic shunting and in these cases the prognosis is good. If there is no resolution of hydrops, there may be an underlying genetic syndrome or infection and in these cases the prognosis is poor.
Recurrence: Isolated or associated with infection: no increased risk.
Part of trisomy: 1%.
Part of genetic syndrome: up to 25%.
