A spinal tap (also called a lumbar puncture) is a test to check the fluid that surrounds and protects your child's spinal cord and brain. Your doctor may have done this test to look for an infection. In some cases, it's done to release pressure from too much fluid. Or it may be done to look for certain diseases.
Your child may feel tired. Their back may be sore where the needle went in. (This is called the puncture site.) Your child may have a mild headache for a day or two. This can happen when some of the spinal fluid is taken out. Some children also have trouble sleeping for a day or two.