Superior hypogastric nerve block versus spinal anesthesia for early pain control after uterine fibroid embolization: a prospective quasi-randomized comparative study.

Purpose

To compare early postprocedural pain and rescue opioid use after uterine fibroid embolization (UFE) in patients treated with superior hypogastric nerve block (SHNB) versus spinal anesthesia.

Materials and methods

This single-center prospective quasi-randomized comparative study included consecutive women with symptomatic intramural uterine fibroids treated between March 2022 and October 2023. Patients were allocated according to a predefined alternating sequence to SHNB or spinal anesthesia. Allocation concealment was not used, and patients, treating teams, and outcome assessors were not blinded. Pain was assessed at 1, 6, and 18 h after embolization using a 0-10 visual numeric scale. Rescue analgesia consisted of 3 mg intravenous morphine for moderate or severe pain according to a standardized institutional protocol. The primary endpoint was any rescue morphine use during the 18-h postprocedural observation period. Secondary endpoints were total rescue morphine dose and pain scores over time. Pain trajectory was analyzed using linear mixed-effects models, and rescue morphine outcomes were analyzed using modified Poisson and Poisson regression models.

Results

Forty-two patients were included, with 21 in each group. Baseline characteristics were reasonably balanced, with all absolute standardized mean differences below 0.40. Rescue morphine use occurred in 13 of 21 patients (61.9%) in each group (risk ratio, 1.00; 95% confidence interval (CI), 0.62-1.61). No significant treatment-by-time interaction was observed for pain trajectory (P = .650), and time-specific between-group differences in pain scores were not significant at 1, 6, or 18 h. In adjusted analyses, treatment group was not associated with pain trajectory, any rescue morphine use, or total rescue morphine dose. Larger fibroid diameter was associated with higher pain burden and greater morphine requirement. SHNB was technically successful in all patients and was not associated with block-related complications during the assessed follow-up window.

Conclusion

In this small prospective quasi-randomized comparative study, no detectable between-group differences were observed in rescue morphine use or early postprocedural pain scores between SHNB and spinal anesthesia after UFE. These exploratory findings support the feasibility of SHNB as a procedural analgesic strategy but should not be interpreted as evidence of equivalence or noninferiority.