The short answer
Anechoic is an ultrasound word. It means an area sends back no echoes, so it looks black on the screen. Fluid, such as in blood vessels or a fluid-filled space, often looks anechoic. The word describes appearance, not a diagnosis.
Anechoic means no echoes come back from an area, so it looks black.
Fluid often looks anechoic. Blood vessels and fluid-filled spaces are examples.
Anechoic describes how something looks, not what it is. Your care team explains what it means in your report.
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This page is for people whose ultrasound report uses the word "anechoic." It explains what the word means and what to ask your care team.
How ultrasound makes a picture
An ultrasound sends sound waves into the body. Tissues bounce some of those waves back as echoes. A computer turns the echoes into a gray picture.
How well a tissue sends back echoes is called its echogenicity. Radiologists use three main words for it:
- Hyperechoic: sends back many echoes. Looks white or bright.
- Hypoechoic: sends back fewer echoes. Looks gray or darker.
- Anechoic: sends back no echoes. Looks black.
What anechoic means
Anechoic means sound passes through an area without bouncing back, so it looks black. An ultrasound teaching review lists blood vessels and fluid-filled spaces as examples. It also lists bone and lymph nodes, so black does not always mean fluid.
A cyst is a closed pocket that may hold fluid. A fluid-filled area can look anechoic, but brightness is only one feature. Your care team can tell you whether yours is a cyst.
What the word cannot tell you
Anechoic describes appearance. It is not a diagnosis. Your report's impression section, and your care team, say what the radiologist thinks the area is.
Ask these before you leave
- What part of my scan is anechoic?
- What do you think it is?
- Were there any solid parts or other features?
- Do I need any follow-up?
Related pages
See What Does Hypoechoic Mean on an Ultrasound?, What Does Complex Cyst Mean?, and Cyst vs Tumor
Sources
Common questions
Does anechoic mean a cyst?
Fluid often looks anechoic, and many cysts hold fluid. But the word only describes how the area looks. Your care team explains what the radiologist thinks it is.
Is anechoic good or bad?
Neither by itself. It is a description of brightness, not a result.
What is the difference between anechoic and hypoechoic?
Anechoic areas send back no echoes and look black. Hypoechoic areas send back some echoes and look gray.
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Sources last checked: 2026-10-02 what this meansLast updated: 2026-10-02Next planned review: 2027-09-27
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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