A lumbar puncture is a procedure that involves having a thin needle put into your lower back. It is usually done to take a sample of the fluid that cushions your brain and spinal cord for testing (a ‘diagnostic’ lumbar puncture). A specialist doctor called a pathologist examines the fluid sample under a microscope to see if it contains any lymphoma cells. They might also run specialised tests on the sample.
Sometimes a lumbar puncture is used to give medicines into the fluid around your brain and spinal cord, through an injection into your lower back.
You might need a lumbar puncture if your specialist suspects that you have lymphoma in your brain or spinal cord. This is called central nervous system (CNS) lymphoma. The lymphoma might begin in your central nervous system (primary CNS lymphoma) or it might spread there from elsewhere in your body (secondary CNS lymphoma). This happens occasionally with some types of high-grade non-Hodgkin lymphoma, such as:
Most people with these types of lymphoma do not develop lymphoma in their central nervous system and not everyone with these types of lymphoma needs a lumbar puncture. Your medical team decides what tests you need based on your individual circumstances.
You might also need a lumbar puncture if your medical team thinks you would benefit from having chemotherapy injected directly into the fluid around your brain and spinal cord (intrathecal chemotherapy). This might be the case if you have CNS lymphoma, or if your medical team think you are at high risk of your lymphoma spreading to your CNS. Having the chemotherapy through a lumbar puncture can help the drugs reach your brain and spinal cord.
Most people who need a lumbar puncture have the procedure as an outpatient and do not have to stay in hospital overnight.
How should I prepare?
You should be given information about the procedure and how to prepare for it. You might have a blood test before the procedure to check that you don’t have any problems with blood clotting. You can eat and drink as normal before the test. Tell your medical team about any medicines, vitamins and other supplements you are taking.
If you usually have medicine to thin your blood, your medical team might ask you to stop taking it a few days before the procedure to reduce your risk of bleeding.
What happens during the procedure?
Before you have a lumbar puncture, the doctor explains what it involves and asks you to sign a consent form.
To have a lumbar puncture, you usually lie on your side and curl up, with your knees pulled up towards your chest. Sometimes, you might need to sit up instead. In this case, you are asked to sit leaning forwards onto a pillow that is resting on a table in front of you. Make sure you are comfortable – you need to keep as still as possible during the procedure.
Very rarely, a lumbar puncture might be technically difficult (for example, if you have curvature of the spine, or if you are obese). In this case, your doctor might recommend an ‘X-ray guided’ lumbar puncture. For this, you lie on your front or side on an X-ray table. The doctor uses real-time X-rays of your spine, displayed on a computer monitor, to help them find the best place to perform the lumbar puncture.
- When you are in the correct position, the doctor cleans your lower back with antiseptic and places a sterile cover over your body. The doctor then injects local anaesthetic into the skin of your lower back. This might sting briefly.
- When the area is numb, the doctor inserts a thin needle into the gap between two bones in your lower spine. You might experience a feeling of pressure in your back.
- The needle enters the spinal canal, which is filled with cerebrospinal fluid (CSF). The doctor inserts the needle at a level that is much lower than your spinal cord so your spinal cord can’t be damaged.
- When the needle is in the right place, CSF starts to drip out. The doctor collects a small amount (usually around one teaspoonful or 5 ml) in sterile tubes.
- If you are having intrathecal chemotherapy, the doctor injects drugs into your spinal canal through the lumbar puncture needle.
- The doctor then removes the needle and puts a plaster or dressing on your skin. You can take this off this the next day.
A lumbar puncture takes about half an hour. It isn’t usually painful but it might be uncomfortable.
What happens after the procedure?
You usually need to lie flat for around an hour after a lumbar puncture. This helps reduce the risk of developing a severe headache.
Most people go home the same day. You need someone else to drive you. You should not drive or operate machinery for at least 24 hours.
You can usually return to your normal activities once you feel well enough but avoid anything too strenuous for at least a week.
Lumbar punctures are generally very safe. The main side effects are a headache, and swelling, bruising or discomfort in your lower back. These usually get better on their own. Contact your medical team if problems persist or are severe.
It is very common to develop a headache after a lumbar puncture. This typically starts within 24 hours of having the procedure. It usually feels worse when you sit or stand up and feels better when you lie down. You might also feel sick.
If you develop a headache after having a lumbar puncture:
- Lie down until it eases.
- Take pain killers. Your medical team can advise you on the best pain relief to use. They might also prescribe anti-sickness medication.
- Drink plenty of fluids. Some people find that caffeinated drinks like tea, coffee and coke, help.
Headaches after a lumbar puncture usually get better within around a week. Contact your medical team if you have a headache that doesn’t get better, or if it gets suddenly worse.
Serious complications after a lumbar puncture are very rare but could include infection or bleeding.
Contact your medical team if you have any of the following:
- a severe headache that doesn’t go away
- fever (temperature above 38°C or 100°F)
- sensitivity to bright lights
- vomiting (being sick)
- blood or fluid leaking from the area you had the injection
- severe back pain
- tingling or numbness in your legs.
Your medical team should give you more information on what to look for and when to seek advice.
It can take anywhere from a couple of days to a couple of weeks to get the results of your lumbar puncture, depending what tests are done on the sample. Waiting for test results can be an anxious time but your medical team are gathering important information at this time so they can give you the best possible treatment.