A blood patch is a medical procedure in which a small amount of a patients own blood is injected into the epidural space to stop a leak of cerebrospinal fluid (CSF) and relieve a post-dural puncture headache (PDPH) . The procedure is done by inserting a needle into the same space or a space just next to the space that was used for the lumbar puncture and injecting autologous blood. The blood acts to patch the hole in the dura (the outer membrane of the spinal cord) that was created by the needle at the time of myelography. The blood patch procedure is highly effective and carries a relatively low degree of risk. Relief from the spinal headache is often felt very quickly, and sometimes immediately after the blood patch is complete. The procedure is permanent, and the bodys own healing system should take over and finish repairing the spinal fluid leak. However, a small number of patients may need to have a second blood patch. The benefits of an epidural blood patch include relief of spinal headaches, and most patients do not report any pain or discomfort during the procedure. The risks of the procedure include infection at the injection site, localized septicemia, and patient refusal or lack of cooperation.