The ganglion impar is a bundle of nerve fibers located in the pelvis near the coccyx (buttock tailbone). It is a sympathetic ganglion, meaning that it is part of the sympathetic nervous system responsible for the body’s “fight or flight” response. The ganglion impar also carries sensory nerves that are responsible for pain in the rectum, anus, vagina, scrotum, tailbone, and bladder/urethra. In a ganglion impar block, local anesthetic and steroid are typically injected near the ganglion impar site to temporarily block pain signals conducted through these pain sensing sympathetic nerves. The ganglion impar block is a safe and effective method of pain control, with a low risk of complications.