Since your brain makes new CSF all the time and replaces it 2 or 3 times a day, the small amount of fluid that is removed will be quickly replaced. The needle is taken out and the puncture site is cleaned and bandaged.įollowing a spinal tap, you may be told to lie flat in bed or with your head slightly raised for 1 to 4 hours. Several small samples of fluid are collected and sent to the lab for study.Ī final pressure reading, called the closing pressure, may be taken after the fluid samples are done. Your doctor takes the pressure reading, called the opening pressure, and checks whether the fluid is clear, cloudy, or bloody. You may be asked to straighten your legs while you are lying down.

When the needle is in the spinal canal, a device called a manometer is hooked to the needle to measure the pressure of the CSF. Your doctor may need to move to another area of your spine if it is hard to get to the spinal fluid. If not, the stylet will be put back in and the needle will be moved in a little farther or at a different angle to get to the fluid. If the needle is in the right spot in the spinal canal, a small amount of cerebrospinal fluid (CSF) will drip from the end of the needle. When the needle is in place, the solid central core of the needle (stylet) is removed. Then a long, thin needle is put in the spinal canal. A numbing medicine (local anesthetic) is put in the skin. The area is cleaned with a special soap and draped with sterile towels. Your doctor marks your lower back (lumbar area) with a pen where the puncture will occur. If fluoroscopy is used, you will lie on your stomach so the fluoroscopy machine can take pictures of your spine during the procedure. These positions help widen the spaces between the bones of the lower spine so that the needle can be inserted more easily. Or you may sit on the edge of a chair or bed and lean forward over a table with your head and chest bent toward your knees. You will lie on a bed on your side with your knees pulled up toward your chest.

If the pressure is high, you may need other tests before the spinal tap. The doctor also may look into your eyes using a special lighted scope (ophthalmoscope) to see if the pressure is high. You will empty your bladder before the procedure. It may also be done in the radiology department if fluoroscopy is used. In total the procedure will take about 30-45 minutes this includes the time to get you ready in the correct position and set up all the equipment.A spinal tap may be done in your doctor's office, in an emergency room, or at your bedside in the hospital.

As soon as the required amount of fluid is collected, the needle is taken out and a sticking plaster put over the site of needle entry. The needle is usually in for about 1-2 minutes. This is done by attaching a special tube to the needle, which can measure the pressure of the fluid coming out. Sometimes the doctor will also measure the fluid pressure. The fluid can also be tested for protein, sugar and other chemicals if necessary. It is also 'cultured' to see if any bacteria grow and what type they are. If you have possible meningitis, this fluid sample is sent to the laboratory to be examined under the microscope to look for germs (bacteria), red blood cells and white blood cells, which are a sign of infection.

Some fluid leaks back through the needle and is collected in a sterile pot. staff, 'Blausen gallery 2014', Wikiversity Journal of Medicine, via Wikimedia Commonsīy staff, 'Blausen gallery 2014', Wikiversity Journal of Medicine, via Wikimedia Commons

Lumbar puncture