Is a bulging disc serious?

Often it is not. The North American Spine Society calls bulges normal wear and common in people without pain, and a 2015 review found them in 30% of pain-free 20-year-olds. Your symptoms and exam decide whether it matters.

Can a herniated disc get better without surgery?

Often, yes. The ACR criteria say most disc herniations show some reabsorption or regression by 8 weeks after symptoms begin. MedlinePlus says pain, numbness, or weakness often goes away or improves a lot over weeks to months.

Do I need a repeat MRI if my back pain comes back?

Often the new scan adds little. The ACR criteria say repeat imaging for a new episode is unlikely to show differences in disc protrusion or annular fissures. New or worsening symptoms after lumbar surgery, or any red flag, are a different case.

Does a bigger herniation mean a worse outcome?

Not reliably. The ACR criteria cite research finding that the size and type of a disc herniation, and the presence of nerve root compression, were not related to patient outcome. Treatment decisions rest on symptoms and exam as well as the images.

Is X-ray or MRI better for lower back pain?

They answer different questions. NIAMS says X-rays show bones only and can help identify fractures and alignment changes, while MRI shows soft tissues such as discs and nerve roots. Most people with back pain do not need either test, according to NIAMS.

What Does a Lumbar Spine MRI Show for Lower Back Pain?

The short answer: A lumbar spine MRI shows the discs, nerve roots, spinal canal, vertebrae, and facet joints of the lower back. It often finds changes that cause no pain. A 2015 AJNR review found disc bulges in 30% of pain-free 20-year-olds and 84% of pain-free 80-year-olds. Your symptoms decide what a finding means.

A lumbar MRI report can read like a list of damage, but much of that list is normal aging. For how radiology reports are laid out in general, see how to read your MRI results.

What can a lumbar spine MRI see?

MRI uses a strong magnet to make cross-sectional images. NIAMS says it can help diagnose damage or disease of soft tissues, including discs, ligaments, and nerve roots. X-rays show bones only. The scan most often takes 30 to 60 minutes.

Discs: These are the cushions between the vertebrae. MRI shows where a disc presses on the spinal canal. An X-ray alone cannot diagnose a herniated disc.
Nerve roots: The ACR criteria say back pain with radiating leg symptoms, or signs of stenosis, suggests nerve root compression that MRI can show.
Spinal canal: The ACR notes that MRI assesses how open the canal is.
Vertebrae: MRI assesses the bone marrow. Per the ACR, marrow swelling helps date a fracture, and MRI helps separate benign from malignant compression fractures.
Facet joints: These small joints sit at the back of the vertebrae. NIAMS explains that their capsules can thicken and form bone spurs, which crowd the nerve roots.

A normal result means the spine and nearby nerves look OK. MedlinePlus says abnormal results are most often due to a herniated disc, spinal stenosis, or lumbar spondylosis (wear on the spinal bones and cartilage).

What do the words on a lumbar MRI report mean?

The standard reference is Lumbar Disc Nomenclature version 2.0, a 2014 consensus from three societies: NASS, ASSR, and ASNR. Here are words you may see, in plain language.

Disc bulge: A broad spread of the disc past its normal edge. NASS describes a bulge as involving about 25% or more of the disc's edge. It calls bulges normal wear and common in people without pain.
Herniation: A localized shift of disc material, involving 25% or less of the disc's edge. Protrusion and extrusion are the two types.
Protrusion: A herniation that keeps a sizable connection to the disc space.
Extrusion: A herniation where a large amount of material extends past the disc space, joined only by a thin stalk.
Annular fissure: A crack in the outer wall of the disc.
Disc degeneration or desiccation: Age-related change. Discs dry out with age and can bulge.
Degenerative changes or spondylosis: General wear on the bones, cartilage, and discs. The 2015 review says many such features are likely normal aging.
Stenosis: Narrowing of the spaces in the spine. This can press on nerve roots. Many people with stenosis have no symptoms.
Foraminal narrowing: Stenosis at the openings where the nerve roots leave the spine.
Facet arthropathy: Wear in the facet joints.
Spondylolisthesis: One vertebra slips forward over another.
Radiculopathy: A condition of the spinal nerve roots, which can cause pain, numbness, or weakness.

How common are these findings in people with no back pain?

Very common, and more so with age. The Brinjikji review pooled 33 articles and 3,110 people without symptoms, scanned by CT or MRI. Estimates by age:

Disc degeneration: 37% at age 20, 96% at age 80.
Disc bulge: 30% at age 20, 84% at age 80.
Disc protrusion: 29% at age 20, 43% at age 80.
Annular fissure: 19% at age 20, 29% at age 80.

The authors concluded these findings must be read in the context of the patient's clinical condition. A second point from the ACR criteria: in one prospective study of people scanned before their back pain began, 84% had unchanged or improved findings after symptoms developed. So a finding on the scan may predate the pain.

Findings still matter. A 2015 meta-analysis of adults 50 or younger found disc bulge, degeneration, protrusion, and extrusion were more common in people with back pain than in people without it. Even so, NASS says degeneration alone cannot identify the source of pain.

When do guidelines recommend a lumbar MRI, and when not?

For most new back pain, guidelines say not to scan. The 2007 ACP and American Pain Society guideline says clinicians should not routinely image nonspecific low back pain. A 2011 ACP paper adds that routine imaging brings no meaningful benefit and can cause harm. A Lancet meta-analysis of six trials and 1,804 patients found no significant difference in pain or function between immediate imaging and usual care. ACP's 2017 update addresses noninvasive treatment.

The 2021 ACR Appropriateness Criteria rate a noncontrast lumbar MRI this way:

Usually not appropriate: Back pain, with or without leg symptoms, with no red flags and no prior treatment.
Usually appropriate: Symptoms that persist or progress during or after 6 weeks of treatment, in a candidate for surgery or another procedure.
Usually appropriate: Suspected cauda equina syndrome, new or worsening symptoms after lumbar surgery, or suspected cancer or infection.
Usually appropriate: Immunosuppression, osteoporosis, chronic steroid use, older age, or low-velocity trauma.

The ACP guideline makes a similar point for sciatica or stenosis. It says to use MRI for persistent symptoms only if you may be a candidate for surgery or an epidural steroid injection. One reason to wait: the ACR says most disc herniations show some reabsorption or regression by 8 weeks after symptoms begin. Insurers apply the same logic, as our guide to MRI prior authorization explains.

The ACR rates MRI without contrast as usually appropriate in all of those scenarios. Contrast helps with certain questions, such as telling scar tissue from recurrent disc herniation after surgery. See our guide to MRI with contrast.

Which symptoms are red flags?

Red flags point to a serious cause, not routine back pain. The ACR red flag table lists these:

Possible cauda equina syndrome or another severe nerve problem: sudden trouble passing urine, overflow leakage of urine, loss of bowel control, numbness in the saddle area (groin and inner buttocks), or weakness in both legs or weakness that is getting worse.
Possible cancer or infection: a history of cancer, unexplained weight loss, immunosuppression, urinary infection, intravenous drug use, prolonged corticosteroid use, or back pain that has not improved with treatment.
Possible fracture: significant trauma, a minor fall or heavy lift in a person who is older or may have osteoporosis, or prolonged steroid use.

MedlinePlus adds fever, trouble walking or loss of balance, severe back pain in children, and very severe pain that medicine does not relieve. It says such signs call for an MRI right away. NIAMS says to see a doctor if pain does not improve after a few weeks.

The ACR no longer treats age over 50 alone as a red flag. It says people over 65 may be at risk of osteoporotic fracture.

What should you ask at the follow-up visit?

Take your report and this list to the visit. If you are still sorting out what a new symptom may mean, symptom.md has plain-language guides.

Which finding, if any, do you think explains my symptoms?
Does the location of that finding match where I feel pain, numbness, or weakness?
Is this finding common for someone my age?
Is it a bulge, a protrusion, or an extrusion, and does it touch a nerve root?
Does this result change my treatment?
Am I a candidate for surgery or an injection, or should I keep the current plan?
Which new symptoms should send me to urgent care?

The bottom line

A lumbar MRI gives a detailed view of the discs, nerves, canal, and bones, but it cannot tell pain from aging on its own. Guidelines reserve the scan for red flags, or for persistent symptoms when the result could change care. Read your report with your clinician, alongside your symptoms and exam.

Last updated: November 2026. This article is for informational purposes only and does not constitute medical advice. Seek urgent care for new bladder or bowel problems, numbness in the groin, or leg weakness that is getting worse.