What it means
An infiltrate is an area of the lung that looks whiter than normal on an X-ray or CT. Something has filled the air spaces or the tissue around them, such as fluid, pus, blood or cells. The word does not say which. Many radiologists now prefer more exact terms, such as opacity, consolidation or ground-glass opacity. Infiltrate can mean different things to different doctors.
When it matters
The word is a description, not a diagnosis. Pneumonia is the most common reason, especially with fever and cough. Other causes include fluid backing up from the heart, bleeding, inflammation and, less often, a tumor. Your doctor reads it alongside your symptoms and tests. If the cause is unclear, or it has not cleared after treatment, a repeat X-ray or a CT is often the next step.
Questions to ask your doctor
- Does the infiltrate look more like pneumonia, fluid or something else?
- Is it new, or was it already there on older chest X-rays?
- Would a CT show more detail than the X-ray?
