Indications for Breast Ultrasound in Patients with Breast Lumps
Breast ultrasound is indicated for all patients with palpable breast lumps, with the exception of women ≥40 years where mammography shows a clearly benign correlate (like lipoma, oil cyst, hamartoma) that unequivocally corresponds to the palpable finding. 1, 2
Age-Based Approach to Imaging
For women under 30 years: Ultrasound is recommended as the first-line imaging investigation due to the low incidence of breast cancer (<1%) and theoretical increased radiation risk of mammography 1, 3
For women 30-39 years: Either ultrasound or diagnostic mammography/digital breast tomosynthesis (DBT) can be used as the initial imaging evaluation 1, 2
For women ≥40 years: Diagnostic mammography or DBT is recommended as the initial imaging modality, followed by ultrasound in most cases 1, 2
Specific Indications for Breast Ultrasound
When mammography is negative but a palpable abnormality is present (to detect cancers occult on mammography) 1
When mammography shows an abnormality that is not clearly benign and correlation with the palpable finding is uncertain 1
To directly correlate clinical and imaging findings, as ultrasound allows real-time examination of the area of concern 2, 4
To determine if a palpable abnormality is solid or cystic, which affects management 2, 5
When a patient reports a breast lump but clinical examination is normal (ultrasound can detect small clinically occult breast cancers) 6, 5
For pregnant or lactating women with palpable masses, as ultrasound is the preferred initial imaging modality 1, 2
Clinical Effectiveness of Ultrasound for Palpable Masses
Ultrasound detects 93-100% of cancers that are occult on mammography 1, 4
The addition of ultrasound to mammography improves detection of benign etiologies for palpable findings (40% of benign palpable masses may be identified only on ultrasound) 1, 4
When both mammography and ultrasound are negative or benign in the evaluation of a palpable breast mass, the negative predictive value exceeds 97% 1, 5
Important Considerations
A palpable mass that persists throughout a complete menstrual cycle requires imaging evaluation, as cyclical breast changes typically resolve after 1-2 menstrual cycles 7
Despite negative imaging, a suspicious dominant palpable finding should still undergo further evaluation, as physical examination findings should never be overruled by negative imaging 1, 5
Imaging should be completed prior to biopsy, as changes related to the biopsy may confuse or limit subsequent image interpretation 1, 2
For masses seen equally well on mammography and ultrasound, ultrasound guidance is preferred for biopsy due to patient comfort, efficiency, absence of radiation, and real-time visualization of the needle 1, 2
There is little to no role for advanced imaging technologies such as MRI, PET, or molecular breast imaging in the routine initial evaluation of palpable breast masses 1, 2