Radiology glossary

What does "disc herniation" mean on your scan?

Part of: Spine findings, explained

Full explainer: Disc Herniation — What It Means on Your Report

One of the soft cushions between your spinal bones has pushed outward from its normal position, which can sometimes press on a nearby nerve.

In plain English: a spinal disc that has slipped out of place.

What it means on Ultrasound

Ultrasound is not used to look for disc herniations because sound waves cannot penetrate the spinal bones to reach the discs. Its strengths lie elsewhere — tendons, muscles, joint fluid, and guiding needle procedures. If your report mentions ultrasound alongside a suspected herniation, it was almost certainly used for a different purpose, such as guiding an injection, while the herniation itself was seen on MRI or CT.

What radiologists look at next

When a radiologist spots a herniation, they characterize it systematically: the exact disc level, the size in millimeters, the direction of displacement, and the shape — protrusion, extrusion, or sequestered fragment. Next they grade the effect on surroundings using careful language: does the material abut, displace, or compress the thecal sac or a specific nerve root, and is there narrowing of the lateral recess or neural foramen? They document associated wear — desiccation, annular fissures, endplate Modic changes — and compare with prior studies to judge whether the finding is new, stable, or changed. Migration direction (whether extruded material has slipped upward or downward from the disc space) is noted because it changes where a surgeon would look. All of this is descriptive groundwork for your doctor, never a diagnosis on its own.

Where it commonly shows up

• L4-L5
• L5-S1
• C5-C6
• lumbar spine
• cervical spine

Questions to ask your doctor

• What treatment options exist for disc herniation at the affected area?
• Is mine a protrusion, an extrusion, or a sequestration — and does the shape change anything?
• Is the herniation touching a nerve root, or actually compressing it?
• How will we tell on a future scan whether it is getting better or worse?
• What symptoms should make me call you promptly rather than wait?
• Could this herniation explain my symptoms, or might something else?

Common questions

Is a disc herniation the same as a slipped disc?

Yes — 'slipped disc' is the everyday phrase for a disc herniation, though nothing has actually slipped out of place. Part of the disc's soft center has pushed through its tougher outer layer. Many herniations cause no symptoms at all, so the finding needs your doctor's interpretation alongside your history and examination.

Can a disc herniation cause pain in my arm or leg?

It can. If the displaced disc material presses on a nerve root that travels down an arm or a leg, pain, tingling, numbness, or weakness can follow that nerve's path — often called sciatica in the leg. Not every herniation touches a nerve, though, and imaging findings do not always match symptoms, so your doctor connects the two.

Why does my report say 'contacting' instead of 'compressing' the nerve?

Radiologists choose these words deliberately. 'Contacting' or 'abutting' means the disc material touches the nerve without clearly squashing it; 'displacing' means it pushes the nerve aside; 'compressing' means it flattens it. The stronger the word, the more likely the finding explains nerve symptoms — but only your doctor can make that call.

Do I need to be worried about a herniation on my report?

A herniation on a report is a description, not a verdict — many people have them without knowing it. What matters is whether your symptoms line up with the level and side of the finding. Bring the report to your next visit and ask your doctor to walk you through what it means for you specifically.

What each test can miss

Where Ultrasound can mislead

There is no pitfall to watch for here because ultrasound simply cannot image the discs — the vertebrae block the sound waves completely. If someone suggests an ultrasound to 'check the herniation,' that is a misunderstanding of what the test can do.

How radiologists tend to phrase it

The lines below are fictional illustrations of common report phrasing — not real patient reports.

L5-S1: 7 mm left paracentral disc extrusion with caudal migration, contacting the descending left S1 nerve root.

A herniation at the lowest lumbar disc, pushing left of center, with material that has slipped downward — touching the S1 nerve that runs down the back of the leg. 'Contacting' is deliberately weaker than 'compressing.'

Broad-based disc bulge versus focal disc protrusion.

The report is distinguishing a wide, shallow disc shape change (bulge, usually age-related) from a narrower-based focal push (protrusion, a true herniation). The shape words matter more than they look.

Sequestered disc fragment noted posterior to the L4 vertebral body.

A piece of disc has broken free and sits apart from the disc, behind the L4 bone. Radiologists flag free fragments because they can migrate away from the disc space.

Focal T2-hyperintense annular fissure without definite extrusion.

A small bright crack in the disc's outer ring is visible, but the radiologist is not convinced disc material has pushed through it. 'Without definite' is honest hedging — the finding is borderline.

What your doctor might do next

Your doctor will usually start by matching the report to you: which level and side the herniation is on, where exactly you feel pain or numbness, and what the physical examination shows — because a herniation only matters if it lines up with your symptoms. If you have older spine images, your doctor will want them for comparison, since a herniation that is unchanged for years reads very differently from a new one. When symptoms and images disagree, or when new weakness, numbness, or bladder changes appear, doctors generally move faster — those are reasons to call promptly rather than wait for a routine visit. Otherwise the next step is usually a conversation, not a procedure: what to watch for, when to re-image, and which specialist, if any, should see you in person. Bring the report, note exactly where you feel symptoms, and ask your doctor to walk you through what the finding means for you specifically.

This is general information only — talk to your doctor about what it means for you.

Related conditions

• Disc Bulge — What It Means on Your Report
• Nerve Root Compression — What It Means on Your Report
• Spinal Stenosis — What It Means on Your Report