Mixing up a screening mammogram (77067) with a diagnostic mammogram (77066) is one of the biggest compliance and patient satisfaction risks in radiology, because screening mammograms are free for the patient (no copay/deductible).
Screening vs Diagnostic
- 77067 (Screening): The patient is completely asymptomatic. This is their routine annual exam. It is covered 100% under the ACA/Medicare preventive rules.
- 77066 (Diagnostic): The patient has a sign, symptom, or abnormality (e.g., a breast lump, pain, or returning to check an abnormal finding from a previous screen). This is subject to copays and deductibles.
Medical Necessity: The Z Code
For a screening mammogram (77067), you MUST use a screening diagnosis code like Z12.31 (Encounter for screening mammogram for malignant neoplasm of breast). Using a symptom code will result in a denial.
Modifier GG and GH
If a screening mammogram turns into a diagnostic mammogram on the same day (because the tech found an abnormality and immediately did diagnostic views), you bill both, but must append Modifier GG to the diagnostic code.