Ultrasound-guided pain interventions in the pelvis and the sacral spine

Ultrasound guidance of infiltrations in the management of chronic pain allows us to visualize in “real time” the advance of the needle and the diffusion of the analgesic agent in and around the pain-generating anatomical structures. It also enables us to avoid important structures, blood vessels, for example, located in the path of the puncture, thus, avoiding complications. The pelvic area has many pain-generating zones, including joints, muscles, and certain specific points, where nerve structures can be compressed. The involvement of these structures can produce pelvic or lower back pain along with pain that radiates to the lower limbs. Owing to its inability to penetrate bone, ultrasound is unable to visualize, and therefore infiltrate, a number of important nerves located on the anterior face of the sacrum, including the ganglion impar, inferior hypogastric plexus, and superior hypogastric plexus. In this article, we describe different techniques for the ultrasound-guided infiltration in the pelvic region, including the sacroiliac joint, pudendal nerve, coccygeal nerves, transsacral block, lateral branches of the posterior sacral roots, dorsal branch of the L5, caudal epidural infiltration, infiltration of the piriformis and gluteus medius muscles, infiltration of the iliolumbar ligament, ganglion impar block, and superior hypogastric plexus block.