Lumbar puncture: what happens and what to expect

What is a lumbar puncture?

A lumbar puncture is a procedure in which a needle is placed between the bones of the lower spine to reach the fluid that surrounds the spinal cord and brain. This fluid is called cerebrospinal fluid, or CSF.

The NHS says it is usually done in hospital. A local anaesthetic numbs the lower back, the needle goes in between the spinal bones and fluid is collected for testing.

Doctors use it to collect spinal fluid for testing and to measure the pressure of the fluid.

What happens during the procedure?

One leaflet says it typically takes around 15 to 20 minutes but can take longer, and another says 20 to 40 minutes. The lower back is cleaned and numbed with a local anaesthetic injection before the needle is placed.

Leaflets say to expect to rest flat for a short period afterwards, and the team caring for you gives the details.

What are the side effects and risks?

Headache, back pain and bruising are common side effects. The headache is the most frequent. It can start from a few hours to two days after the procedure and last for a few days.

Leaflets say lying flat usually helps the headache.

Serious complications are described as extremely rare. Very rare complications include infection, bleeding, nerve injury, hearing loss and double vision. One hospital trust leaflet says serious harm from complications like these occurs in fewer than one in 10,000 lumbar punctures.

When should I get help after a lumbar puncture?

Leaflets list a severe headache that does not ease on lying flat, a fever, neck stiffness or leg weakness as reasons to get urgent advice from the hospital team or NHS 111. The hospital team who did the test, NHS 111 or the GP the same day can advise, and 999 is for emergencies.

When do results come back?

It depends on the test. Some results can come back within a day. Other tests take longer, sometimes up to 10 weeks. The team caring for you can say when to expect them.