From Scans to Certainty: Diagnosing CBA

Diagnosing Congenital Bronchial Atresia (CBA) is a multi-step process. For some, it begins before birth; for others, it requires specialized postnatal imaging during adulthood for a final confirmation. Because CBA can look very similar to other lung conditions, specialists look for a specific “triad” of findings: a blocked airway, a collection of mucus, and trapped air in the surrounding lung ^[1][2].

The Gold Standard: CT Imaging

A Computed Tomography (CT) scan is the most important tool for identifying CBA postnatally ^[3]. Radiologists look for a classic feature known as the “finger-in-glove” sign ^[4]. This occurs when the blocked airway (the bronchocele) fills with mucus and stretches out, creating a tubular, branching shape that resembles the fingers of a glove ^[1][5].

Around this “finger,” the lung tissue typically appears darker and more “inflated” than the rest of the lung because of air trapping ^[6][4].

Prenatal Detection

For parents of a diagnosed child, CBA is often first spotted during routine prenatal ultrasounds, where it usually appears as a solid, very “bright” (hyperechoic) mass in the baby’s lung ^[7].

To get a clearer picture before birth, doctors may use a fetal MRI. A key marker on MRI is the “hyperintense bronchus sign”—a bright, fluid-filled airway that shows up clearly on specific types of scans. This sign is much more common in CBA than in other malformations, making it a helpful tool for early differentiation.

Differentiating CBA from Other Conditions

It is essential for your medical team to distinguish CBA from other Congenital Lung Malformations (CLMs), as the treatment plan may differ.

• CPAM (Congenital Pulmonary Airway Malformation): While CBA is usually a solid-looking mass, CPAM often contains visible fluid-filled sacs or cysts ^[8]. However, “hybrid” lesions that contain features of both CBA and CPAM can occur ^[9].
• Bronchopulmonary Sequestration (BPS): The biggest difference here is the blood supply. A sequestration has an “abnormal” artery that brings blood directly from the body’s main circulation (the aorta) rather than the lung’s own blood vessels ^[10].

The Importance of CT Angiography (CTA)

To rule out a sequestration or other anomalies, doctors often perform a CT Angiography (CTA). This scan uses a special dye to highlight blood vessels, allowing surgeons to see if there is an abnormal “feeding” artery. Identifying these vessels is crucial for safety, especially if surgery is being considered, to avoid unexpected bleeding. Postnatal CT remains the definitive way to confirm the diagnosis, as prenatal imaging can sometimes be misleading ^[11].

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