Mucus plugging on a chest CT: a picture of your airways on one day

The words next to it

Words you may see beside mucus plugging on a report, and what each one changes.

Subsegmental / segmental / lobar

How far up the airway tree the plug sits, from small outer branches to the airway feeding a whole lobe. In an asthma study, plugs in larger, more central airways affected breathing tests more than plugs in small outer ones.

Atelectasis / volume loss / lobar collapse

Part of the lung behind the plug has deflated. On an X-ray, a collapsed lobe can be what a sudden plug looks like.

Segmental hyperlucency

The lung segment behind a blocked airway looks darker than the rest, from trapped air and less blood flow.

Finger-in-glove sign

Mucus filling a larger airway and its branches, so it looks like a gloved finger or a branching tube.

Bronchiectasis / bronchial wall thickening

Widened airways, thickened airway walls, or both. Plugs beside them fit a long-running airway disease, where mucus keeps collecting and inflammation stays active.

High attenuation / hyperdense

The mucus looks denser (brighter) than usual. In ABPA, an allergic reaction to the mold Aspergillus that mostly affects people with asthma or cystic fibrosis, up to 20% of people have plugs like this. In cystic fibrosis, dense plugs point toward ABPA as the cause.

Acute / new / with pneumonia

Mucus that thickened during a recent illness, when infection and inflammation weaken the cough.

When asthma, COPD or bronchiectasis is already in the picture

If you already have one of these, plugs are usually read as part of that disease. In COPD, fully blocking plugs show up on 25% to 67% of CT scans.

The long-standing approach is airway clearance, such as chest physiotherapy or a handheld oscillating device. When plugging comes on suddenly, care centers on fluids, inhaled medicines that open the airways and mucus-thinning medicines.

In one large study of 4,363 people with COPD, plugs in medium-to-large airways went along with a higher risk of death, a link rather than proof that the plugs caused it.

When a single plug turns up with no airway disease

Doctors work out why that airway filled from your history, your symptoms and the whole scan, not from this one phrase.

If the answer isn't clear, a repeat CT or a bronchoscopy (a thin camera passed into the airway) may be part of finding out.

Questions to ask the doctor

• Is the plug in a small outer airway or a bigger one, and has any lung behind it collapsed?
• Does this fit the asthma, COPD or bronchiectasis I already have, or is it something new?
• Did you compare this with an earlier CT, and was the plug there before?
• If you're not sure why this airway is blocked, would a repeat scan or a bronchoscopy help?
• Were any of the plugs dense enough that I should be checked for ABPA?

Often on the same report

• Tree-in-bud

  Tiny spots joined by branching lines at the ends of the smallest airways, which look like a budding tree on the CT. It usually means infection spreading through the small airways, such as bronchopneumonia or TB, though other conditions can cause it.

• Atelectasis

  An area of lung that has partly collapsed, so the air sacs there aren't filling with air. It's common after surgery or a hospital stay, and with shallow breathing or long bed rest. Mild atelectasis causes no symptoms.

• Bronchiectasis

  Some of the larger airways in the lungs have been damaged and are permanently wider than normal. It's often caused by airway inflammation or infection that keeps coming back, and sometimes it starts after a severe lung infection in childhood.

• Bronchial wall thickening

  The walls of the airways look thicker than normal. This usually, though not always, points to inflammation of the airways, from things like asthma, bronchitis and other infections, or smoking-related lung changes.

• Air trapping

  Parts of the lung keep holding air when breathing out, so they stay darker on images taken after a breath out. A small amount is common in healthy people, seen on about half of chest CTs, and mild air trapping may not matter. When there's more than that, it usually points to an airway problem, often in the small airways.

• Consolidation

  Part of the lung that should hold air is filled with something else, like pus, fluid, blood, or cells, so it looks solid and white on the scan. Causes include pneumonia, fluid from heart failure, bleeding, and tumors.

Questions people ask

What is a mucus plug in the lungs?

It's thick mucus filling part of an airway, so air can't move through freely. Plugs are a relatively common finding on chest X-rays and CT scans. In CT research, a plug counts when the mucus blocks the airway opening completely.

Will mucus in the lungs eventually go away?

Some plugs do. Researchers who followed people with asthma saw plugs form and clear over time, while 47% of plugs stayed in the same airway for 3 years, changing in size along the way. Comparing with an earlier CT is how doctors tell a lasting plug from a passing one.

Can mucus plugging mean a tumor?

It can, though a growth is one of several things that block an airway and trap mucus behind it. Infection, an allergic reaction to mold and an inhaled object can do the same.

Is this the same as the mucus plug in pregnancy?

No, they're unrelated. A mucus plug on a chest scan is mucus sitting in the lung's airways, and the one people talk about in pregnancy has nothing to do with the lungs.

Other phrases explained: Pulmonary nodule · Ground-glass opacity · Aortic atherosclerosis · Schmorl's node · Bone marrow edema · Honeycombing · Fibroadenoma