Congenital Lung Malformations Workup

Updated: Dec 23, 2020
  • Author: Khalid Kamal, MD, MBBS, FAAP, FCPS, MCPS; Chief Editor: Suvro S Sett, MD, FRCSC, FACS  more...
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Laboratory Studies

Hemoglobin testing is always valuable in respiratory illness because the result is an important factor in oxygen delivery and in planning surgery, which often involves major vessels.

Renal function tests to measure BUN, serum creatinine, and electrolyte levels are important because of the frequent association of renal anomalies with pulmonary anomalies (usually pulmonary hypoplasia).


Imaging Studies

Chest radiography

Bronchogenic cysts: Bronchogenic cysts are usually fluid-filled lesions and are well circumscribed in the mediastinum. Solid masses may be difficult to differentiate from fluid. Intrapulmonic cysts appear as solitary nodules unless they contain air. Large cysts may be difficult to differentiate from macrocystic cystic adenomatoid malformation (CAM).

Pulmonary hypoplasia: In pulmonary hypoplasia, a mediastinal shift to the side of a homogenous density may be depicted, with compensatory herniation of the uninvolved lung. The associated anomalies (cardiac, skeletal, gut) may be seen.

Pulmonary sequestration: In pulmonary sequestration, an opaque or cystic lesion is seen, depending on the presence of infection.

Congenital lobar emphysema (CLE)

In congenital lobar emphysema, the involved lobe crossing the midline and the compressed normal lung can be seen. This appearance does not change during expiration or in the decubitus position. Vascularity of the involved site is attenuated. The intercostal spaces in the involved site appear widened, and the hemidiaphragm is flattened. Lucent, anteriorly herniated lung pushes the lung posteriorly, as seen on the lateral view. The lesion must be differentiated from contralateral lung hypoplasia and ipsilateral pneumothorax.

Cystic adenomatoid malformation (CAM)

Cystic adenomatoid malformation is seen as a mass of air-filled cystic spaces with mediastinal shift. In a newborn, the lung fluid may not have been absorbed, and the mass may appear fluid filled and homogenous. In an older child, pneumatoceles may be confused with cystic adenomatoid malformation. Pneumatoceles are postinfectious pulmonary cysts. They occur after Staphylococcus aureus infection. However, they are unlikely to recur in the same area of the lung as where cystic adenomatoid malformation occurs. Bronchogenic cysts are central or mediastinal (relatively early embryologic origin) and peripheral or intrapulmonary (late origin). The latter are rare (15%) and tend to be multiple. Congenital lobar emphysema is exceedingly rare in the lower lobes (< 5% of patients). It is associated with respiratory distress and mediastinal shift.

Chest computed tomography (CT) scanning

Bronchogenic cysts

In patients with bronchogenic cysts, CT findings are characteristic. The lesions are sharply marginated and nonenhancing. If the lesions are seen as soft-tissue attenuation instead of water attenuation, differentiating from lymph nodes may be difficult.

Pulmonary hypoplasia

In lung hypoplasia, loss of lung volume and associated anomalies can be seen.

Pulmonary sequestration

In pulmonary sequestration, the findings may be only an unusual solid attenuation. Therefore, CT may have little to add to sonographic and plain radiographic results unless the anomalous vascular supply can be visualized with vascular contrast enhancement.


In congenital lobar emphysema, the involved lobe and its vascularity can be easily outlined as compared to normal lung parenchyma.


Different types of cystic adenomatoid malformation can be differentiated more accurately with CT than with chest radiography. Lesions that may appear to have resolved on radiography can still be identified on the chest CT scan.

Magnetic resonance imaging (MRI)

MRI is particularly useful when delineation of blood vessels is important. It is the study of choice in difficult cases of bronchogenic cysts. The cysts appear bright on T2-weighted images and do not enhance after the administration of gadolinium-based contrast material.

  • Pulmonary sequestration: MRI and magnetic resonance angiography (MRA) can be performed to identify pulmonary pathology, and aberrant systemic vessels. MRI and MRA have been suggested as the diagnostic procedures of choice for evaluating sequestration of the lung.

  • Congenital lobar emphysema: In congenital lobar emphysema, MRI is used to depict the involved lung and its vascular supply.

  • Cystic adenomatoid malformation: In cases of hydrops fetalis in a fetus with a prenatal, MRI may be beneficial for planning surgery. Cysts larger than 3 mm are depicted as areas of increased signal intensity on T2-weighted images.


Prenatal sonograms

Lesions on prenatal sonograms may shrink or disappear with advancing gestational age. Most pulmonary parenchymal lesions appear as echogenic fetal chest masses. The masses may be unilateral (eg, in cystic adenomatoid malformation, congenital diaphragmatic hernia, pulmonary sequestration) or bilateral (eg, in tracheal atresia). A cystic component is seen in cystic adenomatoid malformation and congenital diaphragmatic hernia (CDH) and can make differentiation of these lesions difficult.

  • Pulmonary hypoplasia: In lung hypoplasia, renal malformations, oligohydramnios, decreased fetal movements in neuromuscular disease, dysmorphisms in trisomies, and skeletal dysplasias may be identified. The thoracic-to-abdomen ratio and lung area are useful parameters. Pulmonary arterial flow can be measured by using Doppler studies.

  • Congenital lobar emphysema: In congenital lobar emphysema, a large fluid-filled lobe may be seen.

  • Cystic adenomatoid malformation: In cystic adenomatoid malformation, a unilateral cystic mass is seen. However, the patient's postnatal clinical course and chest radiographic findings may be normal, and CT, MRI, and/or MRA may be indicated.


Cardiac anomalies are associated with pulmonary hypoplasia in many patients. In addition, some cardiac malformations (eg, tetralogy of Fallot, and scimitar syndrome) may lead to pulmonary hypoplasia.

Isotope ventilation scanning

Although specific changes occur on isotope ventilation scanning, this modality seldom adds clinically useful information. In congenital lobar emphysema, decreased ventilation initially occurs, followed by isotope retention. Attenuated vascularity results in decreased perfusion. Sequestration does not fill up at all during the early pulmonary phase, but it does during the systemic (late) phase. The value of radionuclide imaging is limited because of the lack of anatomic details.

Aortography and angiography

Aortographic and angiographic findings are often definitive in sequestration and arteriovenous malformations (AVMs), yet MRI usually makes these studies unnecessary. In pulmonary hypoplasia, aortography and angiography (cardiac catherization) may be performed to evaluate for reduced pulmonary flow, aberrant pulmonary vessels, and scimitar syndrome. In pulmonary sequestration, arterial supply and venous drainage can be outlined.

Pulmonary hypoplasia

In lung hypoplasia, aortography and angiography (cardiac catheterization) may be performed to evaluate for reduced pulmonary flow, aberrant pulmonary vessels, and scimitar syndrome.

Pulmonary sequestration

In pulmonary sequestration, the arterial supply and venous drainage can be outlined. However, MRA has replaced interventional angiography as the diagnostic modality of choice for identifying sequestration vasculature in many centers.

Barium esophagraphy

This test can assist in defining mediastinal masses and blood vessels. The images also outline communication between a pulmonary sequestration and the gut. However, with the availability of CT scanning, barium esophagraphy is no longer necessary.


Other Tests

Pulmonary function tests

Residual volume, vital capacity, total lung capacity, forced expiratory volume in 1 second (FEV1), and midexpiratory flow can be used to compare volumes in selected lung lesions before and after surgical resection.

Monoclonal antibody testing

The ultimate usefulness of testing for elevated levels of cancer antigen (CA) 19-9 in intralobar sequestrations must be established.

Electrocardiography (ECG)

ECG may be performed to evaluate for associated cardiac lesions or pulmonary hypertension.


Diagnostic Procedures


Bronchoscopy can be performed to detect airway malacia, which is present in patients with congenital lobar emphysema, abnormal bronchial branching (eg, eparterial bronchus suis, in which the right upper lobe bronchus arises directly from the trachea). The study can also be performed to detect purulent material, which indicates infection complicating a congenital malformation of the lung, or to diagnose an acquired lesion, such as bronchiectasis.


Bronchography is seldom indicated any longer because computed tomography (CT) scanning can demonstrate most (but not all) cases of bronchiectasis. Bronchography is useful if a bronchial anomaly is suspected. These anomalies are rare but include bronchial agenesis, which leaves a poorly aerated lobe receiving only collateral ventilation, and bridging bronchus, in which the left mainstem bronchus originates from the right side.