Medical Coding Mammography: Guidelines and Tips
Mammography is a specialized radiology service used to detect and diagnose breast conditions, including breast cancer. Accurate medical coding for mammography is essential for proper reimbursement, compliance, and clean claim processing. Coders must understand CPT® codes, diagnosis coding, Medicare rules, and documentation requirements to avoid denials and audits.
Types of Mammography
There are two main categories of mammography services:
Screening Mammography
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Performed on asymptomatic patients.
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Used for routine breast cancer screening.
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Typically performed on a regular schedule based on age and risk.
Diagnostic Mammography
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Performed when a patient has symptoms such as:
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Breast lump
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Pain
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Nipple discharge
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Abnormal findings on a screening mammogram
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Common CPT® Codes for Mammography
Screening Mammography Codes
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77067 – Screening mammography, bilateral (including CAD when performed)
Diagnostic Mammography Codes
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77065 – Diagnostic mammography, unilateral (including CAD when performed)
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77066 – Diagnostic mammography, bilateral (including CAD when performed)
Note: Computer-aided detection (CAD) is now included in these codes and should not be reported separately.
ICD-10-CM Diagnosis Coding Guidelines
Correct diagnosis coding is critical and depends on the reason for the exam:
Screening Mammography Diagnosis
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Z12.31 – Encounter for screening mammogram for malignant neoplasm of breast
Common Diagnostic Mammography Diagnoses
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N63 – Unspecified lump in breast
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R92.0–R92.8 – Mammographic findings (calcifications, asymmetry, etc.)
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N64.4 – Mastodynia (breast pain)
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C50.* – Malignant neoplasm of breast (if cancer is confirmed or suspected)
Medicare and Payer Coverage Guidelines
Medicare Part B covers screening mammograms as preventive services:
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One screening mammogram every 12 months for women 40 and older
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One baseline mammogram may be covered for women 35–39
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Some high-risk patients may qualify for more frequent screenings
Preventive services often have:
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No deductible
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No coinsurance (for screening exams only)
Diagnostic mammograms are billed as medical services and are subject to deductibles and coinsurance.
Documentation Requirements
Complete and accurate documentation must include:
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Patient symptoms (if diagnostic)
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Reason for the exam
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Laterality (left, right, bilateral)
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Clinical history
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Radiologist’s interpretation
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Final report and impression
Missing or vague documentation is a common cause of claim denials.
Mammography Coding Tips for Best Practices
Use Screening vs. Diagnostic Codes Correctly
Never report a screening mammogram as diagnostic unless there are documented symptoms or abnormal findings.
Verify Medical Necessity
Ensure the diagnosis code supports the procedure performed.
Check Modifier Use
Some payers require modifiers such as:
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Modifier 26 – Professional component
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Modifier TC – Technical component
Watch for Frequency Limits
Annual screening limits apply, and claims may be denied if frequency rules are not followed.
Confirm CAD Rules
Do not separately bill CAD—it’s bundled into current CPT codes.
Common Mammography Coding Errors to Avoid
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Using diagnostic CPT codes with a screening diagnosis code
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Missing laterality for unilateral studies
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Billing CAD separately
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Incorrectly applying modifiers
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Not linking symptoms to diagnostic mammograms
Accurate mammography coding requires a strong understanding of CPT® codes, diagnosis coding, payer rules, and documentation standards. Staying current with guideline updates helps prevent denials, ensures compliance, and supports quality patient care.