The Efficacy of Superior Hypogastric Blockade for Postoperative Pain

Nerve blocks are frequently used in daily practice as an anesthetic and analgesia technique for surgery, postoperative pain and chronic pain. Total abdominal hysterectomy causes significant postoperative pain. Epidural blocks are frequently preferred for postoperative pain control, since most of the anesthetists are skilled with neuraxial blocks. However, an epidural catheter placement and epidural injections have some side effects and complications.

Pelvis is innervated by thoracolumbar and sacral segments. Autonomic (sympathetic and parasympathetic) and somatic (motor and sensory) nerves provide innervation of pelvis. The sympathetic nervous system, which transmits nociceptive messages from the viscera to brain, plays an important role in the transmission of visceral pain. Generally, in order to block transmission of nociceptive information from the pelvic viscera to the spinal cord, interruption of sympathetic pathways will be necessary. The sympathetic nerve block on the sympathetic nervous system for the management of chronic pelvic pain has been proposed at three main levels: ganglion impar, hypogastric plexus and L2 lumbar sympathetic blocks. By following the pelvic anatomy, there could be an alternative way for acute pain relief for abdominal hysterectomy: superior hypogastric block.

The superior hypogastric plexus lies retroperitoneally in front of L4 as a bunch of fibers. As these fibers descend, at the level of L5 they divide into the hypogastric nerves. The hypogastric nerves pass downward from L5-S1, following the concave curve of the sacrum and passing on each side of the rectum to form the inferior hypogastric plexus. These nerves continue their down¬ward course along each side of the bladder to provide innervation to the pelvic viscera and vasculature.

The primary indication for superior hypogastric block (SHNB) is visceral pelvic pain, most commonly from malignancy of the ovary, uterus, cervix, bladder, rectum or prostate. Percutaneous SHP blocks can be done by using posterior approach (transdiscal) and paravertebral) and anterior techniques. All of these interventions should be done under guidance of ultrasonography, fluoroscopy, magnetic resonance or computed tomography. Because of the close proximity of SHP to major vessels, and structures like vertebral column (for posterior) and guts (for anterior) are being on the way of the needle, these percutaneous blocks are associated with complications.

SHP block has been performed by anesthetists or surgeons in Kocaeli Derince Training and Research Hospital regularly since they have discovered the advantages of this block technique. Performing SHP block during hysterectomy surgery, gives advantages to rule out these complications by exploring the whole intraabdominal anatomy. Based on the complexity of the pelvic innervation, SHP blocks do not offer a total painless period like central neuraxial blocks for sure. If SHP block is performed in patients who do not have epidural catheters, it can be useful to decrease postoperative pain scores and opioid or NSAID consumption significantly.