BI-RADS
Read Your Scan Editorial Team·Last updated
Written from published radiology references and reviewed for plain language. Not written or signed by a physician, and not a diagnosis. How we write these pages →
In plain language
The standard scoring scale for breast imaging, from 0 to 6, which turns a mammogram or breast ultrasound into an agreed next step. Low categories mean normal or almost certainly benign; the middle of the scale means a short-interval follow-up; the higher ones mean a biopsy is recommended.
Upload your MRI, CT, X-ray or ultrasound — de-identified in your browser — and every finding is mapped onto your images and explained without jargon.
Where you'll see this
The impression of every mammogram, breast ultrasound and breast MRI report.
Your report may word it “BIRADS”, “Breast Imaging Reporting and Data System” or “BI-RADS category”. These mean the same thing.
Questions worth asking your doctor
- Which BI-RADS category am I, and what does that category normally lead to?
- Is the next step a repeat scan or a biopsy, and when?
- Does a category 0 mean something was seen, or only that more pictures are needed?
How often does this turn up?
BI-RADS is on essentially every mammogram, breast ultrasound and breast MRI report, and it is the number most people look for first. It runs from 0 to 6 and its purpose is to turn a radiologist’s impression into a category that everyone downstream reads the same way. Categories 1 and 2 mean nothing suspicious was seen — 2 simply records a benign finding such as a cyst or a calcification that is recognised as harmless. Category 3 means probably benign. Categories 4 and 5 are increasingly suspicious, and 4 is usually subdivided into a, b and c. Category 0 is not a result at all: it means more imaging is needed before a category can be given. Category 6 is reserved for cancer already proven by biopsy.
Does it mean something is wrong?
The number is a recommendation about what to do next, not a diagnosis, and only a biopsy can diagnose. That distinction matters most in the middle of the scale. A category 3 is a statement that something is very likely benign, and the usual response is a repeat scan after a short interval rather than a biopsy — waiting is the recommended action, not a compromise. A category 4 covers a wide range, which is precisely why it is subdivided: 4a is only slightly suspicious and most 4a biopsies turn out benign. What every category above 3 shares is that the next step is defined and prompt, so the situation is being actively managed rather than left.
What to do with it
Each category maps to a standard action. 1 and 2 return you to routine screening. 3 means a follow-up study at a defined interval, typically six months, to demonstrate stability. 4 and 5 mean a biopsy is recommended, and 5 usually means planning starts in parallel because the suspicion is high. Category 0 means the radiologist could not conclude from the images available and needs additional views, an ultrasound, or comparison with previous films — which is common on a first mammogram simply because there is nothing to compare against.
Frequently asked questions
- What does BI-RADS 3 mean?
- Probably benign. The radiologist has seen something with reassuring features but wants to demonstrate it is not changing, so the recommendation is a repeat scan after a short interval rather than a biopsy. Being placed in this category is a statement of low suspicion, not a deferred bad result.
- Does BI-RADS 4 mean I have cancer?
- No. Category 4 means a biopsy is recommended because the appearance cannot be confidently called benign, and it spans a wide range of suspicion — which is why it is split into 4a, 4b and 4c. A large share of category 4 biopsies, particularly 4a, turn out to be benign.
- Why did I get BI-RADS 0?
- Because the study was incomplete rather than because something was found. The radiologist needs more information — extra mammographic views, an ultrasound, or your previous images for comparison — before assigning a real category. It is very common on a first mammogram, where there is nothing prior to compare with.
Standard scoring systems
Still worried about what your report says?
Upload your scan (de-identified in your browser) and your radiologist's report, and every finding is mapped onto the images, explained in plain language and scored. Informational only — not a diagnosis.
Read Your Scan is informational only — not a medical diagnosis, and not a substitute for a licensed radiologist or your doctor. If you have urgent symptoms, seek care.