The codes
| Code | Used for | Base units |
|---|---|---|
| 01937 to 01940 | Image-guided spine injections and nerve destruction | 4 |
| 01991 | Diagnostic or therapeutic nerve blocks and injections (not prone) | 3 |
| 01992 | Same, with the patient prone | 5 |
Base units shown are the standard values most payers use. Check your payer and the current year's CMS base unit file before relying on them.
Expect questions about medical necessity
Many payers, including Medicare contractors, don't consider anesthesia routinely necessary for most injections. They'll pay when the record shows a specific reason, such as:
- The patient can't stay still or cooperate
- Severe anxiety or a documented history of failed attempts without sedation
- A procedure that's more involved than usual
Check your Medicare contractor's local policies and your commercial payers' rules before you take on this work. If the record doesn't show the reason, assume the claim will deny.
When you do the block yourself
If you're the one performing the injection, you bill the procedure itself, not an anesthesia code for it.
This article is general information, not billing, legal or tax advice. Payer rules change; always check current guidance.
Sources
- CMS: Medicare Claims Processing Manual, Chapter 12 (Anesthesia)
- Maryland Workers' Compensation Commission: anesthesia base unit values