Superior Hypogastric Nerve Block (SHNB) for Uterine Artery Embolisation

In this section, we delve into the Superior Hypogastric Nerve Block (SHNB) and its critical role in enhancing patient comfort during Uterine Artery Embolization (UAE). SHNB, a technique employed for pain management, is particularly significant in the context of UAE, a minimally invasive procedure for treating uterine fibroids. We explore the procedural intricacies of SHNB, highlighting its methodology, the importance of precise needle placement, and the use of imaging guidance for optimal efficacy. This nerve block technique not only improves patient experience by significantly reducing pain but also plays a pivotal role in the overall success of UAE procedures. The integration of SHNB in UAE represents a synergistic approach, combining advanced pain management with cutting-edge fibroid treatment, thus enhancing patient outcomes and procedural efficiency.

StepsDetails
Placement of CatheterFor easier needle insertion, the catheter is positioned across the aortic bifurcation and aortogram (5 and 20 degrees cranio-caudal tilt to obtain true antero-posterior view of L5 vertebrae) is taken for better outlining of aortic bifurcation.
Area Preparation1. The area below the umbilicus (5–15 cm below) is thoroughly cleaned and readied in a sterile manner.
2. The entry site of the needle is visualised using a radiopaque object (like a forceps) skin.
Local Anesthesia ApplicationLidocaine is injected into the skin and the front lining of the peritoneum using a needle of 25-gauge size.
Needle Advancement1. A 22-gauge needle (use 18/20 G needle if traversing through large fibroid uterus), guided by fluoroscopy, is carefully advanced to the front of the L5 vertebral body (preferably in the right lower quadrant)
2. Avoiding the disc space is crucial to prevent the very rare occurrence of discitis.
Contrast Medium InjectionAfter reaching bony resistance, 2–5 ml of contrast is gently injected which should reveals a characteristic triangular opacification (cresent shaped on lateral view) of contrast with no vascular opacification.
Choice of Anaesthetic agent1. Around 20 mL of 0.5% Levobupivacaine (S-enantiomers) or Ropivacaine is administered due to central nervous system and cardiovascular toxic effect of bupivacaine.
How to Inject1. Before injection the needle is aspirated to confirm there is no blood.
2. A preliminary test dose of about 3 cc of 0.5% Ropivacaine is then injected.
3. Look for change in heart rate or neurological status
4. Rest of the 17 cc of the total 20 cc (total of 60 mg of Ropivacaine) is injected slowly with intermittent aspiration.
5. It's essential to apply consistent, gentle forward tension on the needle during this process to avoid retraction into other structures.
Concerns of Bowel PenetrationWhile some operators are wary of the needle passing through the bowel, historical data suggest minimal negative outcomes from such methods.
Critical Safety NoteExtreme care is required to avoid injecting into blood vessels, as this can lead to serious complications, including cardiac arrest.
Duration of Anesthetic EffectThe anaesthetic typically remains effective for 8 to 12 hours and can extend upto 3 days, substantially lowering the patient's requirement for narcotic pain relief and consequently reducing the chance of experiencing nausea.
2. Can be repeated in OPD/ day care basis if the patient comes with severe pain
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