Widened airways (bronchiectasis) seen by chance on CT

What the report means

What it is. Bronchiectasis is a condition in which damage to the airways causes them to widen and become flabby and scarred. (MedlinePlus)
How CT shows it. An airway is called widened if its inside is wider than the blood vessel (artery) running next to it, if it does not narrow as it branches outwards, or if airways can be seen within 1 cm of the lung edge. (O'Dowd 2023)
A scan finding is not the same as the illness. Doctors separate widened airways seen on CT from "clinically significant bronchiectasis", which also needs symptoms such as a cough or phlegm on most days or repeated chest flare-ups. (German guideline 2026)

How common it is with age

On screening CTs. Lung cancer screening studies report bronchiectasis in 0.2% to 18.9% of people; most did not say how they defined it. (O'Dowd 2023) A 2025 review lists 9.1% in Korea, 11.7% in Spain and 23% in a US study. (Laska 2025)
Rises with age. Among 27,617 adults in Seoul having a chest CT as part of a health check, 1,005 (3.6%) had bronchiectasis. It was not seen at ages 20 to 29 and reached 7.2% at 70 and over. More than half of those found (566) had none of five breathing symptoms. (Kim 2021)
Who has it more often. In that study, widened airways without symptoms were more common in women, in older people and in people with liver disease, COPD or past tuberculosis. (Kim 2021) People with it found on screening tend to be older and to have smoked more. (Laska 2025)

Why CT can over-call it in older adults

Airways widen with age. The diameter of the airways naturally increases with age, and the artery size and how deeply you breathe in also change the measurement. So the ratio of airway to artery should not be read as a strict cut-off. (German guideline 2026)
Different thresholds. An airway the same width as its artery (a ratio of 1) is sensitive enough to flag bronchiectasis, while a ratio of 1.5 gives the most certainty, according to an international consensus reported in German guidance. (German guideline 2026)
Normal ageing. A 2025 review notes that many people found this way have widened airways with no symptoms and that, in older people, these changes may reflect normal ageing. (Laska 2025)

Checks guidance lists next

No symptoms. German guidance says people with widened airways on CT who do not have the typical symptoms should not have bronchiectasis-specific follow-up. A breathing test may be considered, depending on the scan. (German guideline 2026) See spirometry and COPD screening.
A daily cough or phlegm. The NHS says the main symptoms are a cough that does not go away, coughing up a lot of phlegm and frequent chest infections, and advises seeing a GP for a cough lasting more than 3 weeks. Tests a GP may arrange include a phlegm sample, a chest X-ray, spirometry and blood tests, with a CT to confirm. (NHS)
When the illness is confirmed. German guidance lists a review by a lung specialist with breathing tests, an oxygen level, a blood count, liver and kidney tests, C-reactive protein, antibody (immunoglobulin) levels and a phlegm sample to look for a cause. (German guideline 2026)
Lung screening carries on. The finding does not change who the USPSTF recommends for yearly low-dose CT: adults 50 to 80 with a 20 pack-year smoking history who still smoke or quit within the past 15 years (grade B). (USPSTF 2021) People with bronchiectasis had more lung nodules (53.4% vs 17.8%) and more false alarms (26% vs 17%) on screening, with no evidence of a higher lung cancer risk. (O'Dowd 2023) See lung cancer screening results.

How it ties to your age-based checks

A finding on a lung scan is a good time to make sure your routine checks are up to date:

Other lung findings have their own pages: lung scarring on a chest CT, wide lung artery on a chest CT, emphysema found by chance on CT and lung nodule found by chance.

Who it applies to

Adults told that a chest CT done for another reason shows mild widening of the airways, with no daily cough, phlegm or repeated chest infections. People already diagnosed with bronchiectasis, cystic fibrosis or an immune problem, and children, are outside this page.

The NHS advises an urgent GP appointment or NHS 111 if your cough is very bad or quickly gets worse, you cough up small spots or streaks of blood, or you are more short of breath than usual. Call 999 (911 in the US) if you cough up more than a few spots or streaks of blood, or have severe difficulty breathing. (NHS)

Routine age-based screening

A finding on a chest CT does not replace the routine screenings for your age. See screenings by age and gender.

Where they differ:

When to report and refer. The NHS England quality standard for its lung health checks reports bronchiectasis and suggests referral when it is moderate or severe, meaning the airway is more than 2 times the width of its artery. One UK screening study protocol refers only above 3 times, to primary care, and to a hospital clinic only with symptoms. (O'Dowd 2023) German guidance advises no bronchiectasis-specific follow-up without symptoms. (German guideline 2026)
Is it worth finding? The European statement found no evidence that finding bronchiectasis early on a screening CT helps the person, and very little data on outcomes. (O'Dowd 2023) The Korean authors argue it is important to identify bronchiectasis from the stage without symptoms. (Kim 2021)
How common. Figures range from under 1% to 23% depending on the definition, the population and the age group studied. (O'Dowd 2023)(Laska 2025)

Your doctor decides what your result means for you.

Questions people ask

How common is bronchiectasis on a screening CT?

Lung cancer screening studies report anywhere from 0.2% to 18.9%, partly because they used different definitions. In a Korean study of 27,617 adults having a health check CT, 3.6% had it, rising to 7.2% at age 70 and over. (O'Dowd 2023) (Kim 2021)

Can it just be from getting older?

Partly. Airways naturally get a little wider with age, and reviews note that some widening seen in older adults with no symptoms may reflect normal ageing. (German guideline 2026) (Laska 2025)

Does it raise my risk of lung cancer?

A European statement on screening findings found no evidence of a higher lung cancer risk, though people with bronchiectasis had more nodules and more false alarms on screening. (O'Dowd 2023)

Do I need follow-up if I have no symptoms?

German guidance says people with widened airways on CT but without the typical symptoms do not need bronchiectasis-specific follow-up; a breathing test may be considered. Your doctor decides. (German guideline 2026)

What if I have a daily cough with phlegm?

The NHS advises seeing a GP for a cough that lasts more than 3 weeks. When symptoms are present, guidance lists breathing tests, blood tests and a phlegm sample to look for a cause. (NHS) (German guideline 2026)

Widened airways (bronchiectasis) seen by chance on a chest CT