Discitis

What it means

Discitis is an infection inside one of the spinal discs, the soft, cushioning pads that sit between each pair of vertebrae. Unlike most parts of the spine, discs in adults have very little direct blood supply, which normally helps protect them from infection — but it also means that once bacteria do reach a disc, the body's immune defenses have a harder time clearing them out, and the infection can smolder and spread to the adjacent bone.

Why it appears on a CT or MRI report

MRI is the most sensitive imaging test for discitis and can show it earlier than CT or X-ray. Radiologists look for a disc that has lost its normal signal and height, along with abnormal signal and enhancement in the vertebral bone immediately above and below it, since the infection almost always involves the adjacent bone as well, a combination called spondylodiscitis. The report will note the level involved and often describes any associated fluid collection or abscess nearby, which changes how urgently treatment is needed.

What it usually means

Discitis is uncommon but can occur at any age. In adults it most often follows bacteria travelling through the bloodstream from another site of infection, such as the urinary tract, skin, or a bloodstream infection, or it can follow a spine surgery, disc injection, or other procedure. People with diabetes, weakened immune systems, or intravenous drug use have a higher risk. The classic picture is persistent, worsening back pain, often not relieved by rest or improved much by usual pain medication, sometimes with fever, though fever is absent in a meaningful number of cases, which is part of why the diagnosis can be missed early on. Treatment centers on a prolonged course of targeted antibiotics, guided where possible by a sample of the infected tissue, along with rest and sometimes bracing; surgery is reserved for cases with a large abscess, spinal instability, or nerve compression.

When to follow up

If a report raises discitis, contact your doctor promptly — this is not a finding to sit on, even if it's being mentioned as a possibility to rule out rather than a certainty. Seek urgent care for fever with worsening back pain, new weakness or numbness in the legs, or any new difficulty controlling the bladder or bowel, since these can mean the infection is affecting the spinal cord or nerves and needs same-day evaluation. Even when discitis is ultimately ruled out, the workup itself (blood tests, cultures, sometimes a biopsy) is worth completing so the actual cause of the pain can be found.

A plain-language way to picture it

Think of a spinal disc as a sealed cushion with very little of its own plumbing, almost like a gasket packed between two plates rather than a living, well-supplied tissue. That's normally an advantage, keeping germs out. But if bacteria do slip in, through the blood or through a procedure, the body's cleanup crew can't reach the site easily the way it can elsewhere, so the infection tends to linger and creep into the neighboring bone rather than resolve on its own — which is exactly why it needs medical treatment rather than time alone.