BI-RADS 0: 'Incomplete' Is Not a Diagnosis
SaveBI-RADS 0 means a mammogram is incomplete and the radiologist needs more information, often extra views or an ultrasound. It is common, especially on a first mammogram, and most callbacks are not cancer. The additional imaging assigns a final BI-RADS category from 1 to 5.
Last updated: July 2026
What does BI-RADS 0 mean?
BI-RADS 0 means your mammogram is incomplete, so the radiologist has paused before giving it a final number from 1 to 5. Under the American College of Radiology system, a 0 is an assessment that says more information is needed, not a finding of cancer. According to the National Cancer Institute, a callback for more imaging is a normal part of screening, and most women recalled do not have cancer 1Ref 1National Cancer Institute (PDQ Screening and Prevention Editorial Board) (2025).Breast Cancer Screening.NCI patient screening page supporting that a callback for additional imaging is common and that most women recalled after a screening mammogram do not have cancer. The score usually appears alongside your mammogram screening age and timing: average-risk women are offered screening from age 40, every 1 to 2 years, to at least age 75 2Ref 2American College of Obstetricians and Gynecologists (2017).Practice Bulletin Number 179: Breast Cancer Risk Assessment and Screening in Average-Risk Women.ACOG guidance that comparison with prior imaging and separate evaluation of symptoms are part of careful breast screening. A category 0 is a request for a better picture, not a diagnosis. The final number that later replaces the 0 is what actually guides any next steps.
Why did I get an incomplete result?
A category 0 usually means one area was hard to read clearly or there were no prior mammograms to compare against. Overlapping tissue can create a shadow that looks like a spot on one view but disappears on another, and a dense-breast pattern on your letter makes that more likely. Radiologists also assign a 0 when they want to line your images up against older films. According to the American College of Obstetricians and Gynecologists, comparison with prior imaging is part of careful screening 2Ref 2American College of Obstetricians and Gynecologists (2017).Practice Bulletin Number 179: Breast Cancer Risk Assessment and Screening in Average-Risk Women.ACOG guidance that comparison with prior imaging and separate evaluation of symptoms are part of careful breast screening. First-time and baseline mammograms therefore draw a 0 more often than later, comparable studies. None of these reasons for a 0 points to cancer on its own, and bringing any outside films to the appointment can speed the comparison.
What happens next after a 0?
The next step after a BI-RADS 0 is additional imaging, most often extra mammogram views such as spot compression, or a breast ultrasound. Scheduling usually happens within 1 to 2 weeks, and the follow-up lets the radiologist assign a final BI-RADS category from the 0-to-6 scale. In many cases the result is downgraded to a normal 1 or a benign 2. According to the National Cancer Institute, the large majority of these workups end without a cancer diagnosis 1Ref 1National Cancer Institute (PDQ Screening and Prevention Editorial Board) (2025).Breast Cancer Screening.NCI patient screening page supporting that a callback for additional imaging is common and that most women recalled after a screening mammogram do not have cancer. Only if the extra pictures raise the score to a 4 or 5 does a biopsy come into the conversation. Until then, the workup is about clearer pictures, not treatment.
Should an incomplete result worry me?
An incomplete mammogram is common and, on its own, does not mean cancer. Roughly 1 in 10 screening mammograms leads to a callback, and the great majority resolve as normal or benign. Callbacks happen more often before menopause, when denser tissue is typical, and at a first mammogram with no comparison films. Still, a new lump you can feel alongside a callback is worth mentioning, because imaging and physical findings are read together. According to the American College of Obstetricians and Gynecologists, symptoms are evaluated apart from the routine screening result 2Ref 2American College of Obstetricians and Gynecologists (2017).Practice Bulletin Number 179: Breast Cancer Risk Assessment and Screening in Average-Risk Women.ACOG guidance that comparison with prior imaging and separate evaluation of symptoms are part of careful breast screening. The waiting period is understandably stressful even when the odds are reassuring, and most callbacks are settled in a single return visit.
When an incomplete result needs prompt attention
A callback that keeps getting postponed, or a new lump, skin change, or nipple change you notice while checking your breasts, is a reason to contact your clinician rather than wait. Completing the additional imaging on schedule is what turns a BI-RADS 0 into a clear answer, usually within a few weeks. According to breast-screening guidelines, timely follow-up of an incomplete study is the standard of care 2Ref 2American College of Obstetricians and Gynecologists (2017).Practice Bulletin Number 179: Breast Cancer Risk Assessment and Screening in Average-Risk Women.ACOG guidance that comparison with prior imaging and separate evaluation of symptoms are part of careful breast screening. Gale can help you track the callback appointment and gather the questions worth asking the imaging center. A short list written down beforehand keeps that follow-up visit focused.
Common questions
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When a callback needs closer attention
- —A new lump or thickening you can feel while waiting for callback imaging is a reason to seek prompt clinician review
- —Skin dimpling, puckering, or a newly inverted nipple is a reason to contact your clinician for evaluation
- —Spontaneous bloody discharge from one nipple is a reason to arrange a clinical breast exam
- —A callback that is repeatedly delayed for weeks is a reason to ask your clinician to help expedite the imaging
This article is general health education, not medical advice. What a BI-RADS 0 means for you depends on your images and history, and should be interpreted with a radiologist and your primary care or breast health clinician.
References
- 1.National Cancer Institute (PDQ Screening and Prevention Editorial Board) (2025). Breast Cancer Screening. National Cancer Institute (NCI), NIH. link ✓NCI patient screening page supporting that a callback for additional imaging is common and that most women recalled after a screening mammogram do not have cancer
- 2.American College of Obstetricians and Gynecologists (2017). Practice Bulletin Number 179: Breast Cancer Risk Assessment and Screening in Average-Risk Women. Obstetrics & Gynecology. doi:10.1097/AOG.0000000000002158 ✓ACOG guidance that comparison with prior imaging and separate evaluation of symptoms are part of careful breast screening
2 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy