During a lumbar puncture, you either lie on your side or sit upright. Your back is scrubbed with an antiseptic solution. Local anesthetic medicine is injected into the skin. When the skin is numb from the local anesthetic, a small needle is inserted into your back at the level of the hip bones below the bottom of the spinal cord. The needle is pushed forward gently until the CSF is found. For testing, 1 to 2 teaspoonfuls of fluid are removed and put into special sterile tubes. If you are receiving spinal anesthesia for surgery, no spinal fluid is drained out. The anesthetic medicine is injected directly into the CSF, and your legs and buttocks will begin to feel numb.