Screening vs. Diagnostic Mammography Billing: Codes, Tomosynthesis, and Coverage

Why mammography needs its own rules

Mammography is one of the highest-volume services in many radiology practices and imaging centers. It is also governed by unusual rules: screening and diagnostic exams have different codes, different coverage, and different patient cost sharing. Facilities must be certified under the Mammography Quality Standards Act, and Medicare has specific frequency limits and conversion rules. Errors in choosing between screening and diagnostic codes affect what patients owe, and patients often notice. Getting this right protects both revenue and patient trust.

Screening and diagnostic codes

Screening mammography, bilateral, including computer-aided detection when performed, is reported with 77067. Diagnostic mammography is reported with 77065 for unilateral and 77066 for bilateral exams, also including computer-aided detection when performed. Screening is performed on asymptomatic patients according to recommended intervals. Diagnostic mammography is performed when a patient has signs or symptoms, such as a palpable lump, nipple discharge, or skin changes, a personal history of breast cancer in some payer policies, or when a screening exam shows a finding requiring additional evaluation.

Digital breast tomosynthesis

Tomosynthesis, sometimes called 3D mammography, is reported in addition to the mammogram. For screening, CPT add-on code 77063 is reported with 77067. For diagnostic tomosynthesis, Medicare uses HCPCS code G0279 with the diagnostic mammography code, while CPT and many commercial payers have used other code conventions. Payer coverage of tomosynthesis varies, though many plans now cover it for screening. Verify each payer's codes and coverage.

Medicare frequency and coverage

Medicare Part B covers a screening mammogram every 12 months for women age 40 and older, and one baseline mammogram for women 35 to 39. The Part B deductible does not apply to screening mammography, and there is no coinsurance when the provider accepts assignment. Diagnostic mammograms are covered when medically necessary, with deductible and coinsurance applying. Medicare's 12-month rule counts 11 full months after the month of the last screening, so a screening performed slightly early may be denied.

Commercial plans and the ACA

Under the Affordable Care Act, most non-grandfathered plans must cover screening mammography without cost sharing for women in the recommended age ranges, following federal guidance. Diagnostic mammography and follow-up imaging are often subject to cost sharing, though some states have passed laws requiring coverage of supplemental or diagnostic breast imaging without cost sharing. Check state rules and plan benefits, since they directly affect what patients are told before the exam.

Screening that becomes diagnostic

Medicare allows a screening mammogram to be converted to a diagnostic exam on the same day when the radiologist reviews the screening images and orders additional views while the patient is still at the facility. In that case, both the screening and diagnostic exams may be billed, with modifier GG appended to the diagnostic exam. Commercial plans may follow different rules. Documentation should show the screening results that prompted the additional views and the radiologist's order.

Diagnosis coding

Screening mammograms are coded with Z12.31, encounter for screening mammogram for malignant neoplasm of breast, along with additional codes for risk factors when relevant. Diagnostic exams should be coded with the sign, symptom, or finding that prompted the exam, such as a breast lump or an abnormal finding on a previous image. Using a screening diagnosis on a diagnostic exam, or the reverse, is a common reason for denials and patient complaints.

Preventing mammography denials

Common denials include screening exams performed before the 12-month interval, diagnostic exams without supporting diagnosis codes, tomosynthesis billed with the wrong code for the payer, missing GG modifiers for same-day conversions, and facilities without current certification on file with the payer. Build scheduling checks for last screening dates, maintain a payer code reference, and keep certification documents current.

Communicating with patients

Patients are often confused when a free screening becomes a diagnostic exam with cost sharing. Brief explanations at scheduling and after a callback for additional views help. Staff can explain that the screening is covered as preventive care, while additional diagnostic imaging may involve a deductible or coinsurance depending on the plan. Clear communication reduces billing disputes and supports patient satisfaction.

Supplemental breast imaging

Patients with dense breast tissue or elevated risk may receive supplemental imaging, such as breast ultrasound or breast MRI, in addition to mammography. Federal mammography rules now require facilities to notify patients about breast density in their reports, which has increased questions about follow-up imaging. Coverage for supplemental screening varies widely: some states require plans they regulate to cover it with or without cost sharing, while self-funded plans may not follow those state rules, and Medicare covers ultrasound or MRI only when medically necessary as diagnostic studies. Breast ultrasound is reported with 76641 for a complete exam or 76642 for a limited exam, each unilateral and including the axilla when performed. Breast MRI has its own codes depending on whether contrast and computer-aided detection are used. Authorization may be required, particularly for MRI. Verify benefits before scheduling supplemental imaging and document the risk factors or findings that support it.

Frequently asked questions

Related articles

• Radiology Professional and Technical Components: Using 26 and TC
• MRI Prior Authorization: Match the Order, Protocol, and Claim
• CT Contrast Protocol Documentation: Connect the Record to the Charge