Breast ultrasound is a high-frequency, real-time exam used to evaluate a palpable lump, a mammographic or MRI correlate, nipple discharge, the axilla, implants, and selected screening indications. It does not use ionizing radiation. For clinicians who scan or interpret, the practical sequence is to confirm the indication, survey the region with a linear transducer, label location consistently, and characterize findings so management is clear.
Indications for Breast Ultrasound
Targeted breast ultrasound usually follows a clinical or imaging finding. It does not replace mammography as the primary screening test for most average-risk patients. Typical indications include:
- A palpable breast lump, thickening, or focal pain, especially in dense tissue
- A mammographic mass, asymmetry, or architectural distortion that needs a targeted correlate
- An MRI finding that requires ultrasound correlation or biopsy planning
- Nipple discharge, with attention to ducts and intraductal masses
- Axillary adenopathy or staging of a known malignancy
- Implant integrity and peri-implant tissues
- Guidance for percutaneous biopsy or clip placement
- Supplemental screening in dense breasts in selected patients
Mammography remains better for calcifications and many distortions. Ultrasound is better for cyst-versus-solid characterization, dense tissue, and real-time guidance. A negative targeted scan does not cancel a suspicious mammogram. Adjunct screening technique is reviewed in IAME's screening breast ultrasound course.
Breast Ultrasound Technique and Labeling
Use a high-frequency linear transducer, commonly in the 10 to 18 MHz range. Lower the frequency, widen the field with a trapezoid or virtual convex format, or switch probes when the lesion is deep or the breast is large. Apply ample gel and even compression, especially at the nipple-areolar complex.
Position the patient supine with the ipsilateral arm raised. A posterior oblique position brings lateral tissue onto the chest wall. For a palpable lump, scan under the examining finger so a mobile mass cannot slip out of the field.
Survey
- Image the region of interest in two orthogonal planes, typically radial and antiradial or longitudinal and transverse.
- For a whole-breast survey, cover all quadrants and the retroareolar region with overlapping sweeps.
- Include the axilla when the breast finding is suspicious, when cancer is known, or when nodes are the indication.
- Store cine clips through a mass so margins and compressibility can be reviewed.
Location labeling
Record laterality, clock-face position, and distance from the nipple in centimeters, plus depth and transducer orientation. Clock-face labeling is more reproducible than quadrant language alone and matches ACR-style reporting. Confirm that the ultrasound location matches the mammographic or MRI location before you call a finding a correlate.
Characterizing a Breast Mass on Ultrasound
Describe a breast mass with BI-RADS ultrasound lexicon terms rather than vague labels such as nodule. Core descriptors include:
- Shape: oval, round, or irregular
- Orientation: parallel or not parallel
- Margin: circumscribed, or not circumscribed (indistinct, angular, microlobulated, spiculated)
- Echo pattern: anechoic, hyperechoic, complex cystic and solid, hypoechoic, isoechoic, or heterogeneous
- Posterior features: enhancement, shadowing, combined, or none
- Associated findings: calcifications, vascularity, architectural distortion, duct changes, skin thickening, edema, and lymphadenopathy
Measure three dimensions. Color or power Doppler helps separate an avascular complicated cyst from a solid mass and may show penetrating vessels in suspicious lesions. Simple cysts are anechoic, circumscribed, and show posterior enhancement. Mixed cystic and solid masses need closer scrutiny; see cysts on breast ultrasound for cyst criteria. Feature analysis of solid lesions is covered in sonographic evaluation of benign and malignant breast masses.
Likely benign solid masses are often oval, parallel, and circumscribed. Suspicious masses tend to be irregular, not parallel, and not circumscribed. No single feature is diagnostic. Combine descriptors with the clinical exam and comparison imaging, then assign an assessment using the BI-RADS categories on breast ultrasound.
Suspicious Features and Red Flags
Features that raise concern for malignancy, especially in combination, include irregular shape, non-parallel orientation, angular or spiculated margins, marked hypoechogenicity, posterior shadowing, internal microcalcifications, chaotic or penetrating vascularity, associated distortion or skin change, and abnormal axillary nodes with cortical thickening, hilar loss, or a round shape. A hard palpable mass with these findings warrants prompt correlation and, when indicated, tissue diagnosis. Ultrasound can miss isolated calcifications, so keep mammography in the decision.
Common Pitfalls
- Incomplete palpable survey. Scan under the finger and around it. Mobile lumps escape a small field of view.
- Wrong location. Clock-face errors and missing laterality misdirect biopsy. Recheck against mammography and MRI.
- Pseudolesions. Fat lobules, Cooper ligament refraction, ribs, and the nipple can mimic masses. Change compression and plane, and compare sides.
- Frequency or contact errors. Too high a frequency can hide a deep mass. Too little gel or compression creates shadowing that looks like a lesion.
- Misclassifying cystic lesions. High gain can make debris look solid. A thick wall or mural nodule is not a simple cyst.
- Skipping the axilla when the breast finding is suspicious.
- Treating ultrasound as a mammography substitute for screening or for calcifications.
The report should state the indication, comparison studies, location, size, lexicon descriptors, and a clear assessment with a recommendation. If targeted ultrasound does not explain a mammographic finding, state that clearly so the mammogram drives management.
Consistent technique and lexicon reporting reduce missed lesions and vague follow-up. IAME offers accredited ultrasound CME courses on breast imaging, mass characterization, and screening ultrasound for clinicians who want a structured review of these topics.
Frequently Asked Questions
Why would you get a breast ultrasound?
Order breast ultrasound to evaluate a palpable lump, correlate a mammographic or MRI finding, assess nipple discharge or the axilla, check implants, guide biopsy, or add supplemental screening in selected dense breasts. It is not a stand-alone replacement for screening mammography in most average-risk patients.
How does mammography compare with ultrasound for the breast?
Mammography is the primary screening test and depicts calcifications and many distortions better than ultrasound. Ultrasound characterizes a lump as cystic or solid, evaluates dense tissue, and guides intervention. The tests are complementary. Do not dismiss a suspicious finding on one modality solely because the other is negative.
What are the signs of breast cancer on an ultrasound?
No feature is pathognomonic. Suspicious signs include irregular shape, non-parallel orientation, angular or spiculated margins, marked hypoechogenicity, shadowing, internal microcalcifications, and chaotic vascularity, often with distortion or abnormal nodes. Management rests on the full feature set, the clinical exam, and correlation with mammography or MRI.
What should a breast ultrasound report include?
Include the indication, comparison examinations, laterality, clock-face position, distance from the nipple, three-dimensional size, and BI-RADS lexicon descriptors. Close with an assessment category and a recommendation. If the scan does not explain a mammographic finding, state that clearly.
