Abstract
BACKGROUND: Despite its association with severe postoperative pain, the use of regional anesthesia techniques for penile-inversion vaginoplasty surgery is understudied. This retrospective study aimed to assess the analgesic effects of a saddle block (ultra-low dose hyperbaric spinal anesthesia) with intrathecal (IT) morphine in transgender females undergoing penile inversion vaginoplasty. METHODS: We performed a single-centre, retrospective chart review of 72 patients who underwent penile-inversion vaginoplasty with or without saddle block with IT morphine at our institution over a 26-months period. All patients received standard multimodal intravenous analgesia, and the surgeon administered both a pudendal nerve block and a spermatic cord block as part of routine care. Our primary outcome was cumulative opioid consumption (oral morphine equivalent) at 24h postoperatively. Secondary outcomes included postoperative pain severity, duration of stay in the postoperative care unit and in-hospital, time to first opioid request and incidence of opioid- and block-related side effects. RESULTS: 30 patients received a saddle block with IT morphine and 42 patients received standard analgesia. We found no statistical difference in cumulative opioid consumption at 24h postoperatively (control group: 17.7 mg [5.6, 30.8] vs intervention group 12.5 mg [7.5, 22.5] P: 0.249). The addition of a saddle block was associated with clinically and statistically significant improvements in short-term postoperative pain-related outcomes in the recovery room, including mean and maximum pain severity scores, time to first analgesic request, and duration of stay. While no difference in pain scores was detected at the 24-hour time point, mixed-effects modelling demonstrated lower pain trajectories over time among patients in the intervention group, suggesting a time-dependent benefit. However, the significant time-by-group interaction (p = 0.024) indicates that the difference in pain scores between groups decreased over time. We found no differences in the rates of nausea and vomiting between groups. No saddle block procedure-related complications were reported. CONCLUSION: This retrospective study suggests that despite no statistically significant difference in 24-hour opioid consumption, the addition of a saddle block with 100 mcg of IT morphine is associated with improved PACU pain scores, a longer time to first analgesic request, and a shorter PACU stay. These findings are hypothesis-generating and merit further investigation in a prospective double-blind randomized controlled trial.