BI-RADS 3, 4 and 5 – what do breast examination results mean?

Content author: Iwona Chruścicka, MD, general and oncological surgeon · Editorial work: Wyspa Editorial Team Friendly Medicine · Medical review: Iwona Chruścicka, MD · Date of creation: 07.08.2026 · Date of review: 07.08.2026 · Update: 07.08.2026

The article is of an educational nature and explains the principles of BI-RADS classification. It is not a substitute for discussing a specific result with your doctor - the same category may lead to different management depending on the clinical examination, age, history and previous results. The result should not be interpreted independently.

The most important information at a glance

• BI-RADS is a unified system for describing breast examinations - mammography, ultrasound and MRI.
• The category describes the picture of the lesion and does not make a diagnosis.
• Diagnosis is made only by microscopic examination of the material taken during biopsy.
• BI-RADS 3 indicates a change that is most likely benign and requires monitoring within a short period of time.
• BI-RADS 4 indicates a change requiring verification - and does not equal cancer.
• Category 4 is divided into subcategories 4A, 4B and 4C, which differ in the level of suspicion.
• BI-RADS 5 means a highly suspicious image - treatment is planned immediately, but still after confirmation by biopsy.
• BI-RADS 0 is an incomplete result and requires additional tests - it is not a bad sign.
• Breast density is a separate piece of information and is not the same as the BI-RADS category.
• The category is always discussed in the context of the clinical trial and previous results.

Find out more about the specialist

Iwona Chruścicka, MD, PhD, is a specialist in oncological surgery with many years of experience in the diagnosis and treatment of breast diseases. Discusses the results of imaging tests, qualifies patients for biopsy and guides patients through subsequent stages of diagnostics. In the years 2005–2010, she coordinated a population-based program for early detection of breast cancer in the Pomeranian Voivodeship.

Meet Iwona Chruścicka, MD

What is BI-RADS

BI-RADS is a system for unified description of breast imaging examinations. It was created so that a description made by one radiologist would mean exactly the same to another - and so that each description would clearly indicate what should be done next.

It is used in mammography, breast ultrasound and magnetic resonance imaging. The category ends the description of the study and is its summary - something like a conclusion.

It's important to understand what this category actually describes. BI-RADS tells you how typical or atypical the lesion is - and what course of action follows from it. It doesn't say what the change is. This is a seemingly subtle difference, but it has great practical significance: the category is a guide for the doctor, not a sentence for the patient.

And one thing that I will repeat in this text: diagnosis is made only by microscopic examination of material taken during a biopsy. No BI-RADS category, even the highest one, replaces it.

Whole scale - 0 to 6

Pay attention to category 0, because it can be a source of unnecessary panic. BI-RADS 0 does not mean that something is wrong. It means that the radiologist cannot complete the description because he lacks information - he needs additional projections, a complementary examination or a comparison with photos from years ago. Very often it ends in category 1 or 2.

BI-RADS 3 - most likely benign

This category means a lesion whose picture suggests a benign nature, but is not typical enough to close the case without observation. The probability of malignancy is very low in this group.

The typical approach is to monitor at short intervals, usually after approximately six months, and then at subsequent intervals until the change is confirmed to be stable over time. If the lesion remains unchanged over the established observation period, it is reclassified to a lower category.

Patients often perceive it as being sent back with a note: "if there is something, why should I wait half a year?" So let me explain the logic of this procedure.

Observation is a diagnostic tool here, not postponing decisions. The key information about changes in the breast is whether it changes over time. A lesion that is stable for a certain period of time behaves like a benign lesion - and this information is as valuable as the biopsy result, and it is obtained without any intervention. If we biopsied every lesion in this category, the vast majority of tests would involve completely benign lesions.

What you should do:

• arrange a check-up immediately, on the scheduled date - not "someday",
• do it in the same laboratory if possible, so that the images can be compared,
• take the previous test to the appointment,
• report earlier if the lesion grows, new symptoms appear or you start to feel a lump.

The last point is important: category 3 applies as long as nothing changes. A new symptom invalidates the observation plan and is a reason for an earlier visit.

It also happens that despite category 3, we decide to perform a biopsy - for example, in the case of a strong family history, a disturbing clinical examination or when the patient is unable to function with uncertainty for half a year. This is a justified premise and I speak about it openly because the patient's fear also counts.

BI-RADS 4 - Change Requires Verification

This is the most feared category - mainly because of the word "suspicious". Therefore, I will start with a sentence that I repeat to patients during each such conversation:

BI-RADS 4 does not mean cancer. It means that the image does not allow the change to be considered benign - so it needs to be checked. This is a very broad category and includes situations with completely different degrees of suspicion. That's why it's divided into subcategories.

The difference between 4A and 4C is very large - so it is worth checking in the description whether the subcategory is given and asking the doctor about it. The "four" itself without a letter says much less.

Procedure: biopsy is indicated in this category. Most often, core needle surgery is performed under ultrasound guidance and under local anesthesia. The collected material is sent for microscopic examination, which gives the final answer.

There is another element of this procedure that patients usually do not know about, but which proves the quality of care: the biopsy result is compared with the radiological image. If the image was highly suspicious and the result indicates a benign lesion, such a discrepancy must be explained - sometimes by repeating the biopsy, sometimes by excising the lesion. We don't accept a more convenient answer just because it is more convenient.

BI-RADS 5 - highly suspicious image

This category means that the lesion has features classically attributed to malignant changes - irregular shape, blurred or spiky borders, characteristic microcalcifications, disruption of the architecture of the surrounding tissue.

I will not soften it: the probability of malignant change is high in this category. But the same principle applies here as with all the others - the diagnosis is not made by an image, but by a microscopic examination. A biopsy is necessary not to confirm something that is already known, but because the entire treatment plan depends on its result: the type of lesion and its characteristics determine what treatment will be appropriate.

What is changing in the organization of care: in this category, the procedure is planned in parallel. The biopsy is performed without delay, staging tests are often included, and the patient is referred to the treatment center - most often to a team that deals comprehensively with breast diseases.

I will also say something that does not result from any guidelines, but from many years of practice. A woman who reads "BI-RADS 5" lives in limbo for the next few days - and this is usually the most difficult moment of the whole journey, more difficult than the treatment itself. Don't go through this time alone. Come and discuss the results with someone close to you, write down your questions, and ask them directly what to expect and when. A concrete action plan is the only thing that actually reduces this fear.

What BI-RADS doesn't tell you

• It doesn't make a diagnosis. This is done by a microscopic examination of the biopsy material.
• Does not describe the patient, only the image. The same category for two women can lead to different decisions.
• Does not replace a clinical examination. A palpable lump changes the course of action even with a low category.
• It is not an assessment of the severity of or prognosis.
• Does not say anything about breast density - this is separate information provided in the description.

The last point requires elaboration, because it is most often confused. Breast density describes the structure of the gland — the proportion of glandular tissue to fatty tissue — and is marked separately, usually in letters. It is not a disease or abnormality. However, it is of practical importance: in high-density breasts, changes are more difficult to see on mammography, so additional tests are performed more often.

The second thing worth explaining: the same lesion may receive different categories in different studies. An ultrasound and a mammogram show different things, so the discrepancy is not an error. In such a situation, the highest category determines the course of action - we do not accept the more favorable one.

When not to wait for the check-up date

Regardless of the category in the description, report in advance if you notice:

• a new, palpable lump or enlargement of a previously observed lesion,
• retraction of the nipple or skin, change in the shape of the breast,
• discharge from the nipple, especially bloody or from one breast,
• a skin lesion resembling an orange peel,
• an ulcer or non-healing lesion on the nipple,
• redness and swelling covering a large part of the breast,
• enlarged, hard lymph nodes in the feed or above the collarbone.

The rule is simple: the observation plan remains in force as long as nothing changes. New symptom invalidates this plan.

Most common myths

• "BI-RADS 4 means cancer." No. It requires verification, and most of these changes turn out to be benign.
• "BI-RADS is a diagnosis." No. This is a category for describing the image and a guide on how to proceed.
• "BI-RADS 0 is a bad sign." No. This is an incomplete result and requires additional research.
• "An inspection in six months means sending it back without a receipt." No. The stability of the change over time is important diagnostic information.
• "If something is found, it must be cut out immediately." No. The category and clinical situation determine the procedure.
• "Breast density is an abnormality." No. This is a feature of the gland structure, described separately.
• "Different categories in ultrasound and mammography are an error." No. Research shows otherwise; the higher category decides.
• "Biopsy spreads cancer." No. This is a myth that actually delays diagnosis.
• "Since the biopsy result is benign, case closed." Not always - the result must be consistent with the radiological image.

You have a result with the BI-RADS category and you don't know what to do next?

Don't interpret it yourself at home. During the consultation, we will discuss the description in the context of the clinical trial and previous results and establish a specific plan.

Breast diseases at the Island of Friendly Medicine in Gdańsk

Dr. Iwona Chruścicka, MD, consults patients with breast lesions and disturbing imaging results at the Island of Friendly Medicine. The visit includes an interview, clinical examination of both breasts and lymph nodes, discussion of the examination description and determination of further proceedings - including qualification for biopsy.

It is worth bringing all previous breast examinations, including those from years ago, to your visit. The ability to compare the image over time can be the most important information in the entire diagnostic process. If the situation requires hospital or oncological treatment, the patient is referred to the appropriate center. The current scope of services, availability of dates and prices must be confirmed during registration.

Meet Iwona Chruścicka, MD I feel a lump in my breast

What should I ask when discussing the results?

• What category is in my description and what exactly does it mean?
• Is there a subcategory A, B or C for category 4?
• Is a biopsy needed and if so, what kind?
• Is observation enough and when exactly should I report?
• Is it worth performing a complementary test?
• Does my family history change my behavior?
• Does the density of my breasts influence the selection of tests?
• Is it worth comparing the result with previous tests?
• When will I know the biopsy result and who will discuss it with me?
• What happens if the biopsy result does not match the image?
• What should I worry about before the inspection?
• Can I come to discuss the result with an accompanying person?

FAQ - BI-RADS

What is BI-RADS?

This is a unified system for describing breast imaging tests - mammography, ultrasound and MRI. The category summarizes the description and indicates what action follows from it. It is not recognition.

What does BI-RADS 3 mean?

The change is most likely benign and requires follow-up at short intervals - usually after about six months. The stability of the change over time is important diagnostic information.

Does BI-RADS 4 mean cancer?

No. It means that the image does not allow the lesion to be considered benign and verification with a biopsy is necessary. This is a very broad category - a significant portion of lesions in the 4A subcategory turn out to be benign.

What is the difference between 4A, 4B and 4C?

Level of suspicion: 4A is the lowest, 4C is the highest. The difference between them is big, so it's worth checking whether the letter is included in the description and asking your doctor about it.

What does BI-RADS 5 mean?

An image with features classically attributed to malignant lesions. The probability of a malignant lesion is high, but the diagnosis is still made by microscopic examination - the treatment plan depends on its result.

What does BI-RADS 0 mean?

That the study is incomplete and that additional projections, follow-up testing, or comparison with previous results are needed. This isn't a bad sign - it often ends up being a category 1 or 2.

Why should I wait six months instead of getting a biopsy?

Because observation is a diagnostic tool in this category. A change that is stable over time behaves like a benign change, and this information is obtained without intervention. However, if there are additional reasons, a biopsy may be decided earlier.

Is BI-RADS the same as breast density?

No. Density describes the structure of the gland and is reported separately. It is not a disease, but it affects the visibility of changes on mammography and therefore the selection of tests.

I have different categories for ultrasound and mammography - what now?

This is not an error; studies show different characteristics of change. The procedure is decided by the higher category, and the whole thing is assessed by the doctor in the context of the clinical examination.

Can the category change?

Yes. A lesion that is stable for a specified period of observation may be reclassified to a lower category. New symptoms or enlargement of the lesion may increase the category.

What if the biopsy result does not match the image?

Such a discrepancy must be explained - sometimes by repeating the biopsy, sometimes by excising the lesion. You don't accept a more favorable answer just because it is more favorable.

When should I report before the inspection date?

In case of a new lump or enlargement of the lesion, retraction of the nipple or skin, bloody discharge, ulceration, redness and swelling of the breast and enlarged lymph nodes.

Sources

• Wyspa Medycyny Przyjaznej, M.D. Iwona Chruścicka: https://www.wyspamedycynyPrzyjaznej.pl/pl/dr-iwona-chruscicka
• American College of Radiology, BI-RADS Atlas: https://www.acr.org/Clinical-Resources/Reporting-and-Data-Systems/Bi-Rads
• NHS, Breast screening (mammogram): https://www.nhs.uk/conditions/breast-screening-mammogram/
• NHS, Breast lumps: https://www.nhs.uk/conditions/breast-lump/
• NHS, Breast cancer in women: https://www.nhs.uk/conditions/breast-cancer/
• NHS, Biopsy: https://www.nhs.uk/conditions/biopsy/
• NHS, Breast cysts: https://www.nhs.uk/conditions/breast-cyst/
• NHS, Fibroadenoma: https://www.nhs.uk/conditions/fibroadenoma/
• NICE, Suspected cancer: recognition and referral (NG12): https://www.nice.org.uk/guidance/ng12
• NICE, Early and locally advanced breast cancer (NG101): https://www.nice.org.uk/guidance/ng101
• NICE, Familial breast cancer (CG164): https://www.nice.org.uk/guidance/cg164