Radiology Coding Alert

Question: Can you explain the difference between "diagnostic" and "therapeutic" injections or nerve blocks? How does the provider decide which to do?

Massachusetts Subscriber

Answer: Physicians use diagnostic nerve blocks to determine sources of the patient's pain. These blocks typically contain an anesthetic with a known duration of relief. Therapeutic nerve blocks contain local anesthetic to control acute pain, once the physician confirms the source and cause of discomfort. Most CPT section headings for injection or nerve block codes mention "diagnostic or therapeutic." The codes often cover both situations, which means you could possibly report the same code for both diagnostic and therapeutic injections, based on the type of block and administration site.

Example: A provider might inject an anesthetic and a steroid into a facet joint or a peripheral nerve to determine whether that is the source of the patient's pain. In that situation, a nerve block might be both diagnostic and therapeutic.

But payers may want to know whether the block is diagnostic or therapeutic. Specifying such can be a criterion of coverage. Educate your physicians on the importance of documenting whether the patient receives a diagnostic or therapeutic block.

Remember: Check whether you may report radiological guidance separately or whether it's included. For example, you should not report imaging guidance separately with a code such as 64490 (Injection[s], diagnostic or therapeutic agent, paravertebral facet [zygapophyseal] joint [or nerves innervating that joint] with image guidance [fluoroscopy or CT], cervical or thoracic; single level). The code definition states "with image guidance" and CPT guidelines before the code tell you that fluoroscopy and CT guidance as well as contrast injections are included in 64490.