Good to knowOne result rarely tells the whole story. Your provider looks at your results together with your symptoms, exam, and other tests.
What the test is
Fluid is collected with a lumbar puncture (spinal tap) in the lower back.
Why it's done
- Possible meningitis or encephalitis
- Possible bleeding around the brain with a normal CT
- Multiple sclerosis and other nerve conditions
Getting ready and what happens
- Tell your provider about blood thinners.
How the test is done
- You lie on your side or sit bent forward. After numbing, a thin needle is placed between the lower back bones to collect fluid.
What the results mean
Signs of infection
High white cells and protein with low sugar suggest bacterial meningitis, which is treated urgently.
When a result needs quick action
Call 911Fever with stiff neck, confusion, or a purple rash that doesn't fade
Questions to ask your provider
- What do my results mean for me?
- Do I need to repeat this test or have other tests?
Risks
Some people get a headache afterward, which improves lying flat. Bleeding and infection are rare.
Related conditions
Related tests
Sources
Last updated 2026-11-13.