What Current Procedural Terminology (CPT) codes are used for a diagnostic mammogram and ultrasound (US) to evaluate a breast cyst in a female patient?

CPT Coding for Diagnostic Mammogram and Ultrasound to Evaluate a Breast Cyst

For a patient requiring both a diagnostic mammogram and ultrasound to evaluate a breast cyst, use CPT code 77066 (or 77065 for unilateral) for the diagnostic mammogram and CPT code 76641 or 76642 for the breast ultrasound.

Specific CPT Code Selection

Diagnostic Mammography

• CPT 77065: Diagnostic mammography, including computer-aided detection (CAD) when performed; unilateral
• CPT 77066: Diagnostic mammography, including CAD when performed; bilateral

The choice between unilateral and bilateral depends on whether one or both breasts require diagnostic evaluation 1.

Breast Ultrasound

• CPT 76641: Ultrasound, breast, unilateral, real time with image documentation, including axilla when performed; complete
• CPT 76642: Ultrasound, breast, unilateral, real time with image documentation, including axilla when performed; limited

Use 76641 for a complete breast ultrasound examination, which is appropriate when evaluating a breast cyst as part of a diagnostic workup 1.

Clinical Context for Code Selection

Age-Based Imaging Approach

For women ≥30 years with a palpable mass or suspected cyst:

• Diagnostic mammogram + ultrasound is the standard approach 1
• Both modalities are complementary and typically performed together 1

For women <30 years:

• Ultrasound is the initial examination of choice 1
• Diagnostic mammogram may be added if ultrasound shows suspicious findings 1

Cyst Characterization Considerations

The ultrasound evaluation will classify the cyst as:

• Simple cyst (BI-RADS 2): Benign finding requiring only routine screening 1
• Complicated cyst: Low malignancy risk (<2%), may require follow-up or aspiration 1
• Complex cyst: Contains solid components, requires further evaluation or biopsy 1, 2

Important Coding Caveats

Diagnostic vs. Screening Distinction

• Always use diagnostic codes (77065/77066) when evaluating a specific clinical finding like a breast cyst, not screening codes (77067) 1
• The presence of a palpable abnormality or cyst automatically makes this a diagnostic examination 1

Bilateral vs. Unilateral Coding

• If the cyst is unilateral but bilateral diagnostic mammography is performed for comparison, use CPT 77066 (bilateral) 1
• For ultrasound, code only the side(s) actually examined 1

Digital Breast Tomosynthesis (DBT)

• If DBT is performed instead of or in addition to standard diagnostic mammography, use appropriate add-on codes 1
• DBT is rated as equally appropriate to standard diagnostic mammography for evaluating breast masses 1

Common Pitfalls to Avoid

Do not use screening mammography codes when a patient presents with a known breast cyst or palpable finding—this is always diagnostic 1.

Do not unbundle the examination—if both mammography and ultrasound are medically necessary for cyst evaluation, both procedures should be coded separately as they provide complementary information 1.

Ensure proper documentation of the clinical indication (breast cyst evaluation) to support the medical necessity of both imaging modalities 3, 4.