Decision guide · Updated October 6, 2026
Describe the location and triggers
Bring a simple diagram of where pain begins and travels and note movements that reliably reproduce it. Sacroiliac and lumbar facet tests rely on a broader clinical picture; no single symptom settles the question.
A pain map and examination may narrow the possibilities without settling them. A diagnostic injection is most informative when the clinic states what result would support or weaken each hypothesis.
Compare proposed injections
An SI joint injection targets the pelvic joint; a lumbar facet injection or medial branch block targets a spinal joint or its nerve supply. Ask whether each proposed procedure is a diagnostic test, treatment, or both, and how image guidance will be used.
Ask whether the clinician has examined the hip and neurologic function as well as the back and pelvis. A single area of tenderness can reflect more than one structure. A named working diagnosis should remain open to revision as new evidence appears.
Interpret a mixed result
Improvement in one pain component may leave another unchanged. Track the familiar symptom separately from general soreness. Discuss what additional evaluation is warranted if an injection result does not match the original hypothesis.
Have the clinician explain how a short anesthetic response differs from longer-term change, especially if steroid is included. If only one of several pains improves, that may narrow the question without solving the entire case.
Questions to ask
- What findings favor the SI joint over lumbar facets or the hip?
- What exact structure will the procedure target?
- How will we interpret partial relief?