Superior Hypogastric Plexus Nerve Block in Minimally Invasive Gynecology: a Randomised Controlled Trial.

Abstract

OBJECTIVE\nTo assess the efficacy of a superior hypogastric plexus nerve block in reducing opioid requirements in the first 24 hours after minimally invasive gynecological surgery.\n\n\nDESIGN\npatient-blinded randomised controlled trial SETTING: Single-center academic institution, Sydney Women s Endosurgery Centre (SWEC). Two surgeons administering the blocks in their own surgeries.\n\n\nPATIENTS\nPatients undergoing either laparoscopic or robotic-assisted laparoscopic hysterectomy or myomectomy for benign indications.\n\n\nINTERVENTION\n10mL 0.75% ropivacaine infiltrated into the retroperitoneal space overlying the superior hypogastric plexus vs control of no-block given at the completion of surgery.\n\n\nMEASUREMENTS\nPrimary outcome was the total opioid use in first 24h after surgery, measured in Morphine Milliequivalents (MME). A standardized fentanyl patient-controlled analgesia (PCA) was given to all patients in the trial. Secondary outcome was pain measured on a visual analogue scale (1 to 10) at 1, 2, 6, 12 and 24-hours post-surgery.\n\n\nMAIN RESULTS\n50 patients out of 56 patients approached for the study entered and completed the study (89.2%). Patients were randomized over a 5-month period, March to July 2020. 27 patients were randomized to receive a nerve block and 23 to the control. There was a difference of -21.8 MME in the block group compared to the no-block group (95% CI -38.2 - -5.5, p=0.008). This correlated to a 38% reduction in opioid use in the block group. The mean opioid use in block patients was 33.1 MME (95% CI, 24.2 - 41.9) and in the non-block group 54.9 MME (95% CI, 40.7 - 69.1). For the SHPB group opioid use ranged from 1.0-76.5 MME with an interquartile range (IQR) of 37 (14-51). For the control group the range was 7.5- 113.5 MME with a higher IQR of 60 (28-88). Pairwise comparisons of mean pain scores over the 24 hours showed a lower pain score with a nerve block of 1.8 (95% CI 1.5 - 2.1) compared to no-block of 2.6 (95% CI 2.3 - 2.9) No adverse effects of local anesthetic toxicity, nerve injury or bowel/vascular injury were noted in any patient.\n\n\nCONCLUSION\nA superior hypogastric plexus block is a simple technique for reducing post-operative opioid requirements and pain in the first 24 hours after minimally invasive gynecology.