Superior Hypogastric Plexus Block
This procedure is indicated for pain that originates from the pelvis and is unresponsive to lumbar or caudal epidural blocks. The hypogastric plexus con-tains visceral sensory fibers that bypass the lower spinal cord. This block is usually appropriate for patients with cancer of the cervix, uterus, bladder, prostate, or rectum. It may also be effective in some women with chronic noncancer pelvic pain.
The hypogastric plexus contains not only postgan-glionic fibers derived from the lumbar sympathetic chain, but also visceral sensory fibers from the cer-vix, uterus, bladder, prostate, and rectum. The supe-rior hypogastric plexus usually lies just to the left of the midline at the L5 vertebral body and beneath the bifurcation of the aorta. The fibers of this plexus divide into left and right branches and descend to the pelvic organs via the left and right inferior hypo-gastric and pelvic plexuses. The inferior hypogastric plexus additionally receives preganglionic parasym-pathetic fibers from the S2–S4 spinal nerve roots.
The patient is positioned prone, and a 15-cm needle is inserted approximately 7 cm lateral to the L4–L5 spinal interspace. The needle is directed medially and caudally under fluoroscopic guidance so that it passes by the transverse process of L5. In its final position, the needle should lie anterior to the inter-vertebral disc between L5 and S1 and within 1 cm of the vertebral bodies in the anteroposterior view. Injection of radiopaque contrast confirms correct position of the needle in the retroperitoneal space; 8–10 mL of local anesthetic is then injected. The superior hypogastric plexus block may also be per-formed using a transdiscal approach, though there is a risk of discitis associated with this procedure.
Complications include intravascular injection and transient bowel and bladder dysfunction.