CPT codes are a standardized language for describing medical, surgical, and diagnostic procedures to payers like insurance companies. These codes ensure uniformity in billing and documentation across the healthcare system. CPT Code 77066 identifies a specific type of breast imaging procedure: diagnostic mammography. Understanding this code is necessary for both healthcare providers and patients navigating medical billing and coverage.
Defining CPT Code 77066
CPT 77066 is the code for a Diagnostic Mammography, Bilateral, which may include computer-aided detection (CAD) when performed. CPT stands for Current Procedural Terminology, a system developed and maintained by the American Medical Association (AMA). The procedure involves an X-ray examination of both breasts during the same session. This imaging is initiated to follow up on a specific concern, symptom, or abnormal finding, not as a routine check-up.
The purpose of a diagnostic mammogram is to evaluate suspicious changes in the breast tissue noted by a patient or physician. Symptoms can include a palpable lump, unexplained breast pain, nipple discharge, or skin changes. It is also used when a prior screening mammogram revealed an area of concern requiring a detailed look. If CAD is included, specialized software analyzes the images to highlight potential problem areas for the radiologist.
This procedure provides more detailed views than a standard screening, which typically involves two standard views of each breast. The diagnostic exam allows the technologist and radiologist to target specific areas. They can take additional magnified or spot compression views to better characterize the abnormality. The use of CPT 77066 indicates a medically necessary evaluation prompted by a specific clinical finding rather than preventive care.
Diagnostic Versus Screening Mammography
The distinction between diagnostic and screening mammography is the most significant factor for patients, particularly concerning cost and coverage. Screening mammography (CPT 77067) is a preventative service performed on asymptomatic women to check for breast cancer. Under the Affordable Care Act (ACA), most private insurance plans and Medicare Part B cover annual screening mammograms without patient cost-sharing.
Diagnostic mammography (CPT 77066) is not a preventative service but a response to a medical necessity. This necessity is established by a patient’s symptoms or an abnormal result from a prior imaging test. Because it is considered a diagnostic service, it is often subject to the patient’s regular health plan benefits, such as deductibles, co-pays, or co-insurance. More than 70% of commercially-insured patients faced out-of-pocket expenses for diagnostic follow-up tests in 2023.
To justify CPT 77066, the provider must submit documentation using specific International Classification of Diseases, Tenth Revision (ICD-10) codes. These codes specify the patient’s symptoms or indicate an abnormal finding from a previous test. The ICD-10 code provides the medical justification for performing the diagnostic procedure. This documentation separates the covered preventative service from the cost-shared investigative service for the payer.
What Unilateral Means in Practice
CPT 77066 is the code for a bilateral diagnostic mammogram, meaning both breasts are imaged. The concept of laterality is central to accurate billing, as the corresponding code for a single breast is CPT 77065, designated for a unilateral exam. The choice between 77066 and 77065 depends entirely on the scope of the medical concern being investigated.
A provider uses CPT 77066 when the diagnostic evaluation requires imaging of both breasts. This is often necessary because the abnormal finding or symptom requires comparison with the opposite breast. The procedure includes a full examination of both the right and left breasts to ensure a comprehensive diagnosis, especially if the initial screening was abnormal or symptoms are vague.
The unilateral code, CPT 77065, is used only when the abnormality or symptom is clearly confined to a single side. For instance, if a patient presents with a palpable lump definitively located only in the left breast, the provider orders a unilateral diagnostic mammogram focusing solely on that side. Correctly choosing between the bilateral (77066) and unilateral (77065) code ensures the service scope aligns with the claim submitted to the insurance company.