CPT codes provide a standardized, five-digit language for reporting medical procedures and services to payers, ensuring uniformity in billing and record-keeping. CPT Code 76642 specifically reports a type of diagnostic breast ultrasound procedure. Understanding the precise definition and appropriate usage of this code is necessary for both patients and providers navigating diagnostic imaging.
Defining Unilateral and Complete Breast Ultrasound
The full description of CPT Code 76642 is “Ultrasound, breast, unilateral, real time with image documentation, including axilla when performed; complete.” “Unilateral” specifies that the procedure involves the examination of only one breast, and the code is reported once per breast examined.
For a study to qualify as “complete,” the radiologist must perform a thorough, systematic survey of the entire breast tissue on that single side. This comprehensive examination requires imaging and documentation of all four distinct quadrants of the breast and the retroareolar region (the area immediately behind the nipple).
The procedure must also include the adjacent axilla (armpit region) when medically appropriate and performed. The images must be captured in “real time,” meaning they are dynamic, and they must be permanently documented. Failing to document the required four quadrants and retroareolar region means the procedure may not meet the criteria for a complete study.
Clinical Indications and Medical Necessity
CPT Code 76642 is tied to medical necessity, meaning the test must be ordered to answer a specific clinical question. The procedure is diagnostic, not intended for routine, asymptomatic screening. A common indication is the follow-up evaluation of a finding identified on a prior screening mammogram, such as asymmetry or a suspicious mass.
A patient with a palpable mass or lump detected during an exam also warrants this complete diagnostic study. The ultrasound provides detailed information on whether a lump is a simple, fluid-filled cyst or a solid mass requiring further investigation. This code is also utilized to evaluate dense breast tissue (ACR Category C or D density), where mammography alone may be limited.
Other symptoms justifying a complete unilateral ultrasound include unexplained nipple discharge or localized skin changes. The physician must document the precise clinical reason using an appropriate diagnosis code (ICD-10) to support the medical necessity. Without a justifiable clinical indication, the payer may deny the claim.
Differentiating Complete and Limited Studies
The distinction between a complete (CPT 76642) and a limited (CPT 76641) breast ultrasound is based on the scope of the examination and anatomical coverage. CPT 76642 requires the comprehensive mapping of the entire breast, including all four quadrants and the axilla, to search for abnormalities.
A limited study (CPT 76641) focuses only on a specific area of concern and does not require systematic imaging of the entire breast. For example, it might be ordered solely to assess a known, simple cyst or confirm a biopsy clip location. The choice between the two codes is determined by the imaging physician based on the full extent of the examination documented in the medical record, not merely the initial order.
Billing Guidelines and Required Documentation
Accurate billing for CPT 76642 requires careful attention to modifiers and documentation to ensure proper reimbursement. Since the code is unilateral, a specific modifier must be used to indicate the side examined: -RT for the right breast or -LT for the left breast. If a complete study is medically necessary on both breasts during the same session, the code is reported with the -50 modifier (Bilateral Procedure). This modifier instructs the payer to reimburse the service at a higher rate, usually 150% of the unilateral fee schedule amount.
Robust documentation is mandatory and includes a formal, written report by the interpreting radiologist detailing findings, measurements, and the final assessment. The report must conclude with a Breast Imaging Reporting and Data System (BI-RADS) score, which standardizes interpretation and follow-up recommendations. Incomplete documentation, such as missing axilla images or a lack of a comprehensive report, can lead to “down-coding” or denial of the claim.