Superior hypogastric plexus nerve block in minimally-invasive gynaecology: a double-blind randomised controlled trial

Clinical trial to evaluate the efficacy of a superior hypogastric plexus nerve block with 10ml 0.75% ropivacaine in reducing opiate requirements in the first 24 hours after minimally invasive gynaecological surgery. This was a double-blind RCT at a single institution. Primary outcome was the total opiate use in first 24h after surgery (in morphine milliequivalents). Secondary outcome was patient pain measured on a visual analogue scale (1 to 10) at 1, 2, 6, 12 and 24-hours post-surgery. Patients were randomised over a 5-month period, March to July 2020. 27 patients were randomised to receive a nerve block and 23 to the control. There were no significant demographic or intraoperative differences between the two groups. 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.