Final answer:
A written explanation must accompany a claim when utilizing an unlisted code to justify the medical necessity of procedures or services. ICD codes are commonly found in medical laboratories for test identification and within healthcare management systems for treatment verification.
Step-by-step explanation:
When using an unlisted code, a written explanation must accompany the claim. This is essential to provide the insurance company with the necessary details they need to understand why a specific, standard code was not suitable and to justify the medical necessity of the services or procedures performed. Medical coders use ICD codes to assign the proper codes for procedures performed, and medical billers, in turn, use this information to process claims for reimbursement by insurance companies.
Two locations where you would likely find an ICD code include medical laboratories, where it is used to identify tests that must be performed to confirm a diagnosis, and the health-care management system, which verifies treatments and laboratory work are appropriate for the diagnosis. Additionally, vital-records keepers and epidemiologists rely on ICD codes for various health statistics and records.