Final answer:
The correct statement is that external cause codes are never reported as a first-listed diagnosis in the ICD coding system. They are supplementary to main diagnosis codes and used in numerous healthcare-related processes such as laboratory testing, medical billing, and epidemiological statistics.
Step-by-step explanation:
The correct statement among the ones provided is C. external cause codes are never reported as a first-listed diagnosis. In the ICD coding system, external cause codes provide additional information about the circumstances under which an injury or health condition occurred, but they are not used as the primary diagnosis. Instead, they are supplementary to the main diagnosis codes.
As for the ICD codes themselves, they are an integral part of the healthcare process. For example, when a patient seeks treatment for a viral infection, clinicians use ICD codes to order necessary laboratory tests and tailor the treatments to the specific virus. Likewise, medical coders and billers use these codes to ensure the proper procedures are coded for, which then facilitates accurate billing and claims processing with insurance companies. Furthermore, vital-records keepers use ICD codes to record cause of death on death certificates, and epidemiologists rely on them to track morbidity and mortality statistics.
Therefore, two locations where you would likely find an ICD code are in the medical laboratories for test identification and in the records of healthcare management systems for treatment and laboratory work verification.