A lumbar puncture is a medical procedure which involves inserting a hollow needle between the spinal bones of the lower back, into the fluid which surrounds the lower part of the spinal cord. This fluid is called the cerebrospinal fluid (CSF). A sample of this fluid is usually taken to be tested in the laboratory.
A doctor or specially trained nurse will do the lumbar puncture. It can be done in an outpatients department or on a ward at the hospital. Lumbar punctures are usually carried out using a local anaesthetic. Intrathecal chemotherapy is where chemotherapy is given into the fluid around the spinal cord during a lumbar puncture.