The CPT code for a screening mammogram is 77065, while a diagnostic mammogram uses code 77066. These codes distinguish between routine breast cancer prevention exams and those ordered due to symptoms or abnormal findings.
CPT code 77065 describes a bilateral screening mammogram performed without contrast, typically for asymptomatic women aged 40 and older. It includes imaging of both breasts and interpretation by a radiologist. Code 77066 applies when imaging is focused on a specific concern-such as a lump, pain, nipple discharge, or an abnormality seen on a prior exam-and may involve additional views or targeted imaging.
These codes are standardized under the American Medical Association's Current Procedural Terminology (CPT) system. They ensure consistent documentation across healthcare providers and insurers. For example, Medicare covers CPT 77065 annually for women aged 40 and above, but only allows reimbursement for 77066 when medically justified.
When a woman schedules a routine check-up, her provider orders CPT 77065. This code reflects a preventive service, often covered at 100% under most insurance plans, including Medicare Part B. The procedure takes about 20 minutes and involves compressing each breast between two plates to capture clear images.
If a patient reports a new lump, the doctor orders a diagnostic mammogram using CPT 77066. This code accounts for extra time and complexity-such as magnification views, spot compression, or ultrasound correlation. It may also include follow-up imaging if needed. Because diagnostic exams are not preventive, they are subject to copays or deductibles depending on the plan.
A real-world example: A 52-year-old woman with no symptoms gets a screening mammogram. Her insurer bills CPT 77065 and pays $120. Later, she returns with a palpable mass. The radiologist performs a diagnostic study with additional views. The claim uses CPT 77066 and incurs a $50 copay. The correct code choice ensures accurate billing and proper care tracking.
There are two primary CPT codes for mammograms:
| Code | Type | Use Case | Typical Coverage |
|---|---|---|---|
| 77065 | Screening | Asymptomatic women, annual check-ups | 100% coverage under Medicare and most private plans |
| 77066 | Diagnostic | Abnormal findings, symptoms, prior abnormalities | Subject to copay/deductible; requires medical justification |
Common errors include using 77065 for symptomatic patients. This leads to denied claims and potential audits. The American College of Radiology states that improper coding occurs in nearly 15% of mammogram cases, often due to confusion between screening and diagnostic intent.
Another mistake is assuming that a screening mammogram includes all necessary follow-up. If a radiologist identifies a suspicious lesion during a 77065 exam, the patient must return for a diagnostic study coded 77066. Billing the initial screening with 77065 and adding follow-up services under the same code violates payer guidelines.
One frequent misunderstanding is that CPT 77065 can be used for bilateral imaging even if only one breast is being evaluated. That is incorrect. The code specifies bilateral imaging. If only one breast is imaged, the correct code is 77065 with modifier 52 (reduced services) or 77066 if diagnostic.
Another correction: digital mammography and tomosynthesis (3D mammography) are not separate CPT codes. CPT 77065 includes both modalities when performed as a screening exam. However, if 3D imaging is done during a diagnostic study, the code remains 77066, but a separate code-77067-is used for the tomosynthesis component.
For example, a patient with a history of breast cancer undergoes a diagnostic mammogram with tomosynthesis. The radiologist captures standard 2D images and then acquires 3D slices. The billing uses 77066 for the 2D diagnostic portion and 77067 for the 3D acquisition. Using only 77066 would underbill the service.
I once reviewed a claim where a clinic billed CPT 77065 for a patient who had a known mass detected on ultrasound. The patient was referred for a diagnostic mammogram. The insurer rejected the claim because the code did not match the clinical indication. After correcting the code to 77066 and submitting supporting documentation, the claim was approved. This case highlights how code selection directly impacts payment and compliance.
Always verify the patient's history and reason for the exam before selecting the code. The Centers for Medicare & Medicaid Services (CMS) requires that diagnostic codes be supported by clinical documentation. If a provider cannot justify the use of 77066, the claim will be denied.
Understanding the difference between CPT code 77065 and 77066 prevents billing errors, ensures proper reimbursement, and supports accurate health records. Always match the code to the clinical purpose of the exam.