Scans and X-rays
What Does Effusion Mean on a Scan Report?
Effusion · say it: eh-FYOO-zhunAlso written: fluid collection, pleural effusion, joint effusion, pericardial effusion
Short answer
An effusion is extra fluid that has collected in a space in the body, such as around the lungs, in a joint or around the heart.
What it means
Effusion means a build-up of fluid in a space where only a small amount is normally present. The report usually names the place, such as a pleural effusion (around the lungs), joint effusion (inside a joint) or pericardial effusion (around the heart).
Effusions can have many causes, including infection, inflammation, injury, heart or kidney problems, and others. The report describes the effusion; the cause is worked out separately.
Reports often say whether an effusion is small, moderate or large. Small effusions may need no treatment; larger ones may be drained or tested.
Where you may see it
- Chest X-ray and CT reports
- Knee and other joint ultrasound or MRI reports
- Echocardiogram reports
📄 How it looks on a report
Small left pleural effusion.
🙅 What it does not mean
- It does not tell you the cause. Many different conditions can cause an effusion.
- A small effusion is not necessarily serious. Some are minor and go away.
- It is not the same as fluid inside the lung itself.
🗒️ Questions to ask your doctor
🧾 Reports where you will see “Effusion”
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🔗 Read more from trusted sources
- “Effusion” on MedlinePlus ↗
US National Library of Medicine
- NCI Dictionary definition ↗
US National Cancer Institute: “effusion”
- RadiologyInfo.org ↗
Radiological Society of North America and American College of Radiology
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General information about a medical word, not advice about your own results. Ask the clinician who ordered the test what it means for you.