Facet medial branch block is a diagnostic injection used to evaluate patient suitability for ablation therapy, such as radiofrequency neurotomy/rhizotomy.

Under intermittent fluoroscopy, the sites of the medial branch nerves that serve the facets are identified. A needle is passed to the sites identified, and a small amount of local anesthetic is delivered.

An initial report is obtained from the patient concerning the change in their pain post-injection compared to pre-injection.

If the post injection improvement is adequate, the patient may be referred for neurotomy/rhizotomy.