Final answer:
An ancillary diagnostic code refers to ICD codes used for additional tests and procedures that assist in a diagnosis, and it is crucial for various health-care processes including reimbursements. You can commonly find these codes on medical lab test orders and vital records.
Step-by-step explanation:
A medical assistant classifying services that a patient requires would identify an ancillary diagnostic code as one that is used for additional tests and procedures that support a doctor's diagnosis. These codes are often found within the International Classification of Diseases (ICD) coding system. For example, when a patient is suspected of having a viral infection, an ICD code specific to that virus would be used by health-care professionals to order the necessary laboratory tests to confirm the diagnosis.
These codes are essential for processing through the health-care management system to ensure the treatments and lab work performed correlate with the diagnosis. Medical coders use ICD codes to assign the proper code for procedures performed; medical billers then use this information to process claims for reimbursement by insurance companies. Two locations where you would likely find an ICD code are on medical lab test orders and vital records such as death certificates.