A Unilateral Diagnostic Mammogram is a type of diagnostic imaging test that takes specialized X-ray pictures of one breast (unilateral test). Unlike a routine screening mammogram, which is done on both breasts to look for early signs of disease, a diagnostic mammogram is problem-focused. It is performed when there is a specific concern—such as a new lump, focal breast pain, nipple discharge, skin changes, or an abnormality seen on a screening mammogram—and it provides more detailed views of the area in question.

During the exam, the breast is gently compressed to spread out the tissue so small changes are easier to see. The technologist and radiologist may take multiple views and may include spot compression and magnification views to better evaluate tiny calcifications or subtle structural changes. In many cases, this test is paired with a targeted breast ultrasound to further characterize a finding, especially in people with dense breast tissue.

This test does not “measure” a blood value; instead, it creates images that a radiologist interprets. Results generally fall into a few practical categories:

Normal/benign findings: The images may show no concerning abnormality or show common non-cancerous changes (such as cysts or benign calcifications). In this case, you may be told to return to routine breast screening or to have short-interval follow-up imaging, depending on the finding.

Probably benign finding: Some findings are very unlikely to be cancer but may need repeat imaging (often in about 6 months) to confirm stability over time.

Suspicious or highly suspicious finding: If the mammogram shows features that could represent breast cancer or another significant condition, the next step may be additional imaging and/or a breast biopsy to obtain a definitive diagnosis.

Radiology reports commonly use the BI-RADS system (Breast Imaging Reporting and Data System) to standardize results and recommendations. Your clinician will review the findings with you and explain whether follow-up, ultrasound, MRI, or biopsy is recommended.

A unilateral diagnostic mammogram is usually ordered to evaluate a specific symptom or breast abnormality in one breast or to take a closer look at a finding from a screening mammogram. It helps clinicians determine whether a change is likely benign, needs close monitoring, or requires further testing.

Common reasons your doctor may order a unilateral diagnostic mammogram include:

New breast lump or thickening: A focused lump evaluation can help distinguish benign causes (like a cyst) from findings that need biopsy.

Abnormal screening mammogram: If a screening study shows an asymmetry, mass, distortion, or calcifications in one breast, diagnostic views can clarify what it is.

Focal breast pain or tenderness: While many cases of breast pain are not related to cancer, targeted diagnostic imaging may be appropriate when pain is localized or accompanied by another finding.

Nipple discharge or nipple changes: Especially if discharge is spontaneous, persistent, from a single duct, or bloody; or if there is new nipple inversion or crusting.

Skin changes: Dimpling, redness, thickening, or “orange peel” texture can prompt diagnostic evaluation.

Follow-up of a known breast finding: Short-interval imaging is sometimes recommended to ensure a probably benign finding remains stable.

Post-surgical or post-treatment evaluation: Imaging may be done to assess a specific area after lumpectomy, biopsy, radiation, or breast infection/inflammation.

High-risk history or clinical concern in one breast: Your clinician may order diagnostic imaging based on personal history of breast cancer, strong family history, known genetic risk, or a concerning exam—even if a recent screening exam was normal.

Because it is targeted, a unilateral diagnostic mammogram can speed up answers and reduce unnecessary testing by focusing on the exact area of concern in one breast.

• Breast cancer (including ductal carcinoma in situ and invasive breast cancer)
• Benign breast cysts
• Fibroadenoma (benign breast mass)
• Fibrocystic breast changes
• Suspicious breast calcifications (benign or malignant causes)
• Mastitis and breast abscess (breast infection/inflammation)
• Fat necrosis (often after trauma or surgery)
• Intraductal papilloma (can be associated with nipple discharge)
• Breast asymmetry or architectural distortion (imaging findings that may require further workup)

• Evaluating a new breast lump, thickening, or other breast abnormality promptly
• Clarifying an abnormal screening mammogram finding in one breast
• Supporting early detection of breast cancer and timely treatment planning
• Guiding next steps in care (targeted ultrasound, MRI, or biopsy) based on radiology results
• Monitoring a probably benign finding to confirm stability over time
• Assessing breast symptoms (localized pain, nipple discharge, skin or nipple changes) for reassurance or further evaluation
• Supporting women’s health and individualized breast screening strategies, especially for people with dense breasts or higher risk