Imaging for sciatica
Sciatica is pain that radiates from the lower back into the buttock and down the leg, typically along the L5 or S1 nerve distribution. Most cases improve over four to eight weeks with conservative care. Imaging matters when symptoms persist or when red flags appear.
When sciatica does and doesn't need imaging
ACR and Choosing Wisely guidance: early imaging for acute sciatica without red flags is generally not recommended because outcomes do not differ from delayed imaging. Imaging becomes appropriate when:
- Progressive weakness in the leg
- New bowel or bladder dysfunction (cauda equina syndrome — emergency)
- Saddle anesthesia
- Symptoms persisting beyond six to eight weeks despite conservative care
- Surgical or injection consultation is being considered
- Major trauma, cancer history, infection risk, or unexplained weight loss
For new bowel or bladder dysfunction with leg weakness, go to an emergency department.
Which scan for which problem
Lumbar MRI without contrast is the test of choice. It shows discs, nerve roots, the spinal canal, and the conus medullaris in fine detail.
CT is used when MRI is contraindicated.
Lumbar X-ray does not directly show the source of sciatica but may be appropriate to evaluate alignment or spondylolisthesis.
What the recommended scan shows
Lumbar MRI evaluates each disc level for herniation or bulge, the neural foramina for narrowing, the central spinal canal for stenosis, and the lower nerve roots for compression. The report should correlate the affected level with your symptom distribution (e.g., L5 vs. S1).
Common diagnoses and what they mean
Disc herniation with nerve root compression — the classic cause of sciatica. The majority improve without surgery over weeks to months.
Lumbar stenosis — bilateral leg pain with walking that is relieved by sitting.
Spondylolisthesis with foraminal narrowing — slip of one vertebra over another, pinching exiting nerve roots.
Less common causes — synovial cyst, schwannoma, infection, tumor. MRI evaluates these well.
What happens after results
Many patients with imaging-confirmed disc herniation improve with physical therapy and oral anti-inflammatories alone. Transforaminal epidural steroid injections are an option for persistent symptoms. Surgery (microdiscectomy) is reserved for failure of conservative care or progressive neurologic deficit.
How to get the scan at Precise
Bring your physician's order. Most studies are performed without contrast and take about 30 to 45 minutes. See our lumbar MRI page for locations.
Frequently asked questions
How to schedule at Precise
Once you and your physician decide imaging is the right next step, scheduling is quick. Bring your prescription, photo ID, and insurance card.
Condition overview
Learn more about the specific conditions associated with this symptom — what imaging is used, what it shows, and how to schedule at Precise.
Find imaging near you
Precise Imaging has locations across California with same-day scheduling, board-certified radiologist reads, and transparent pricing.