Superior hypogastric nerve block

Superior hypogastric nerve block is a valuable tool for pain relief in the setting of uterine fibroid embolization. This procedure results in significant ischemic pain, peaking at 6-8 hours and lasting approximately 24 hours, then followed by a lesser degree of post-embolization pain which can last for several days. Acute pain is typically managed with IV opiate analgesia, necessitating overnight hospital admission. Use of superior hypogastric nerve block can allow for UFE on a day case basis. 

Indications

Intraprocedural and postprocedural pain relief for uterine fibroid embolization. Superior hypogastric neurolysis has also been used for the control of pain from pelvic malignancy.

Contraindications

• allergy to the intended local anesthetic agent
• cellulitis or other infectious/inflammatory processes at the intended skin entry site

Procedure

Preprocedural evaluation

Prior CT or MRI is useful but not essential to check the position of aortic bifurcation and evaluate for structures such as the uterus within the expected needle path.

Positioning/room set up

• patient supine
• sterile prep of lower abdomen, and apply fenestrated drape - best done at outset of procedure when prepping vessel entry site (femoral or radial)
• antibiotic prophylaxis, e.g. 2g cefazolin IV

Equipment

• Chiba needle 20-21G, 15-20cm length
  • 20G needle will provide improved pushability if traversing the uterus
• connecting tube
• 1% lidocaine
• long-acting local anesthetic, such as 0.5% bupivacaine or 0.5% ropivacaine
• contrast media

Technique

• tube in AP position with ~15^o craniocaudal angulation, aiming for a true AP view of the L5 vertebral body
• mark position of aortic bifurcation using limited angiogram, or by passing a catheter across the bifurcation if using femoral access
• fluoro to mark skin entry site, over the inferior aspect of the L5 vertebral body
• subcutaneous local anesthetic with 1% lidocaine
• insert Chiba needle under fluoro guidance, until bone is felt; take care to avoid aortic bifurcation and intervertebral disc
• remove stylet and inject 3 mL 1% lidocaine to anaesthetize periosteum; monitor for tachycardia which would suggest intravascular injection
• move to lateral view and inject 2-5 mL contrast, check spread of contrast in prevertebral space, confirm no vascular filling
• inject 10 mL long-acting local anesthetic
• fluoro in AP view to confirm bilateral spread of contrast/anesthetic mixture, then inject another 10 mL anesthetic; if satisfactory bilateral spread is not seen, reposition needle before injecting the second aliquot of anesthetic
• remove needle

Complications

• discitis: due to inadvertent needle puncture of disc, especially after traversing bowel
• local anesthetic systemic toxicity

Outcomes

Superior hypogastric nerve block is associated with improved pain scores and reduced opiate analgesia requirement following UFE ^1-3. A corticosteroid (for example 40mg triamcinolone) can be added to the injectate and has been shown to prolong the duration of pain relief ⁴.