Superior Hypogastric Nerve Block for Pain Control Post-uterine Fibroid Embolization

Prospective Blinded Study Looking at PO/IV Analgesia Alone Versus PO/IV Analgesia With Superior Hypogastric Nerve Block for Uterine Artery Embolization Pain Management

Uterine fibroid embolization (UFE) is now an accepted treatment of uterine fibroids. However the procedure is often very painful and, in many centres, patients are admitted overnight with patient controlled analgesic (PCA) pumps for pain control and discharged the next day with heavy pain medications. The goal of this study is to evaluate the effectiveness of a superior hypogastric nerve block (SHGNB) in controlling the pain post-UFE.

This is a double blinded study in which the patients and the primary operators of the UFE as well as the post-procedural caregivers are blinded to whether the patients have received a sham procedure (injection of xylocaine in the skin in the peri-umbilical region) or the superior hypogastric nerve block. The superior hypogastric nerve block (SHGNB) consists of advancing a 21g Chiba needle via an anterior approach up to the superior hypogastric nerve plexus and injecting 20cc of 0.75% Ropivacaine which is a long lasting local anesthetic agent. The nerve plexus is positioned below the aortic bifurcation along the anterior surface of the vertebral body. By fluoroscopy, the location can be identified by having a catheter crossing the aortic bifurcation. That way, we are able to target, under fluoroscopy, the anterior surface of the vertebral body just below the catheter. Our UFE starts with a right common femoral artery (CFA) access. The catheter is crossed to the left side and the left uterine artery embolized with polyvinyl alcohol (PVA) 500-700 particles. The operator will then leave the room. Another operator will come and perform either the hypogastric nerve block or the sham procedure (injection of xylocaine in the periumbilical subcutaneous tissues). If the hypogastric nerve block is done, the needle is advanced into position via an anterior periumbilical approach under fluoroscopic guidance. Once the bony surface is contacted, 3 cc of xylocaine is injected to numb the area and then 3-6 cc of contrast is injected to ensure that it drapes the anterior vertebral body surface. If it spreads along both sides of the vertebral body and there is no vascular intravasation of contrast, the 20 cc of Ropivacaine is injected. If it only drapes one side, 10 cc is injected and the needle repositioned to the other side, the position verified with contrast, and the left over 10 cc of Ropivacaine injected. After the block or sham procedure is done, the primary operator enters the room again and the UFE completed with embolization of the right uterine artery. The patient is transferred to the recovery room and monitored. Pain medication including fentanyl and midazolam are offered at routine interval or on patient request. Pain scales are measured routinely and the patient is discharge home with a pain survey with visual analog pain scales to be performed routinely for 10 days. The patient is followed up in 4-6 months with a follow-up magnetic resonance imaging (MRI) and consultation to look at the results of the procedure. Comparison of the pain scale reports and use of pain medication will be evaluated between both groups to determine if there is a statistically significant difference.

Superior hypogastric nerve block performed during UFE. 20cc of 0.75% Ropivacaine injected at the superior hypogastric nerve plexus.

21g Chiba needle advanced into the superior hypogastric plexus via an anterior infraumbilical approach using the arterial catheter as a fluoroscopic landmark to target the vertebral body below.

mg Equivalent Morphine Used Until Discharge From Recovery Room to Control Pain Level Below 4/10 (VAS)

mg equivalent morphine used until discharge from recovery room to maintain pain level below 4/10 (visual analog scale 0/10=no pain to 10/10=worse pain the patient could imagine)

Number of patients with Grade C/D/E/F adverse events (Society of Interventional Radiology (SIR) Classification). Per Society of Interventional Radiology (SIR) Classification: Grade C, require therapy, brief hospitalization (<48 hours); Grade D, require major therapy, unplanned increased level of care, prolonged hospitalization (>48 hours); Grade E, permanent adverse sequelae; Grade F, death.

Inclusion Criteria: All women with symptomatic fibroids or adenomyosis that have requested and been approved for uterine artery embolization Ability to comply with the requirements of the study procedures Exclusion Criteria: Patients in whom the vascular anatomy prevents access to the superior hypogastric nerve plexus safely Patients who have known allergy to the anesthetic agent Patients with signs of skin infection at the entry site of the needle used to place the nerve block Patients with signs of infection such as fever Patients with history of inflammatory bowel disease of with signs of colitis Patients with uncorrectable abnormal coagulation status (INR >1.5 and plt < 50000 without use of anticoagulation agents) Patients with preexisting conditions, which, in the opinion of the investigator, interfere with the conduct of the study. Patients who are uncooperative, cannot follow instructions, or who are unlikely to comply with follow-up appointments or fill-out the post-procedural pain questionnaires. Patients with a mental state that may preclude completion of the study procedure or is unable to provide informed consent

Rasuli P, Jolly EE, Hammond I, French GJ, Preston R, Goulet S, Hamilton L, Tabib M. Superior hypogastric nerve block for pain control in outpatient uterine artery embolization. J Vasc Interv Radiol. 2004 Dec;15(12):1423-9. doi: 10.1097/01.RVI.0000137406.09852.A4.

Yoon J, Valenti D, Muchantef K, Cabrera T, Toonsi F, Torres C, Bessissow A, Bandegi P, Boucher LM. Superior Hypogastric Nerve Block as Post-Uterine Artery Embolization Analgesia: A Randomized and Double-Blind Clinical Trial. Radiology. 2018 Oct;289(1):248-254. doi: 10.1148/radiol.2018172714. Epub 2018 Jul 10. Erratum In: Radiology. 2019 Jul;292(1):269.