Question: How should I code a piriformis muscle injection using fluoroscopic guidance? Washington Subscriber Answer: Your coding depends partly on how your physician documents the procedure and the policy of the payer in question. If your physician only documents an injection into the muscle, report 20552 (Injection[s]; single or multiple trigger point[s], one or two muscle[s]). Some coders say 64445 (Injection, anesthetic agent; sciatic nerve, single) could also be appropriate if your physician blocks the sciatic nerve. (The piriformis muscle affects the sciatic nerve and can cause leg and back pain, which could be why the patient comes to your physician.) But some payers say you should report 64999 (Unlisted procedure, nervous system) because CPT does not include a specific code for the procedure. When you report the fluoroscopy, submit 77002 (Fluoroscopic guidance for needle placement [e.g., biopsy, aspiration, injection, localization device]) with modifier 26 (Professional component).