A lumbar puncture (also called a spinal tap)may be used to diagnose cancer, as well as treat it.
The term ‘lumbar’ refers to your lower back, between the pelvis and the ribs. Most people have several lumbar punctures throughout their treatment.
How does it work?
During a lumbar puncture, a very small needle is inserted between two of your vertebrae. Using this needle, a small amount of spinal fluid is withdrawn to check for cancer in your central nervous system.
A chemotherapy drug may also be injected through this needle to treat your cancer (referred to as intrathecal chemotherapy).
Lumbar punctures take about 20 minutes. Usually, you are asked to lie on your side and "curl up into a ball", knees bent and pulled up as far as possible with your chin touching your chest.
How long will it take?
In this position, the vertebrae in your spine separate, allowing the needle to pass between them and into the spinal canal.
A local anaesthetic is used to numb the skin before the needle is inserted. However, even with the local anaesthetic you might still feel some discomfort.
Will it hurt?
Try to use relaxation techniques like deep breathing and visual imagery to stay calm.
When the test is done, a piece of sterile tape is applied to your skin where the needle was inserted.
What happens afterwards?
Your medical team will tell you exactly what to do after the procedure, but you will usually be told to lie flat on your back for at least an hour to prevent a headache (caused by the temporary imbalance of your spinal fluid).
Even with this precaution, you may still have a headache for several days that that gets worse when you sit or stand up.