A lumbar puncture (LP), is performed in order to take a sample of the fluid circulating around the brain and spinal cord.
The baby lies on its side in a foetal position so that the vertebrae are slightly separated. Using his/her fingers, the doctor locates the space between the vertebrae and inserts a very fine needle into the baby's lower back, then the spinal fluid slowly drops into a test tube.
The baby will be given pain relief and may also experience the discomfort of being placed in a foetal position and restrained. It can be comforting for the baby to be able to suck on a dummy or a finger during the procedure to reduce the stress. The fluid in the spinal cord is usually replenished within an hour.