A post-dural puncture headache (PDPH) is caused by a leakage of spinal fluid from a hole in the dura, the covering over the spinal cord. Left untreated, the condition almost always resolves on its own but can take anywhere from days to months. Conservative management consists of bed rest, lots of fluids and the intake of caffeine. Most doctors will perform a blood patch if 24-72 hours of this therapy fail to improve the headache. An epidural blood patch is done by injecting some of the patient's blood into the epidural space. This then clots and seals the hole.