Comparative Efficacy of the Erector Spinae Plane Block and Serratus Posterior Superior Intercostal Plane Block in Breast Surgery: A Randomised Trial

Background Regional anesthesia manages pain and supports recovery following breast surgery. The Serratus Posterior Superior Intercostal Plane (SPSIP) block provides broad coverage and may enhance pain relief. This study compares pain control, opioid use, and patient satisfaction between Erector Spinae Plane (ESP) and SPSIP blocks. Method This randomized, single-blind study included 75 patients undergoing reduction mammoplasty, modified radical mastectomy, or breast implant surgery between June 2024 and January 2025. Patients were assigned to ESP, SPSIP, or control groups. We compared pain scores (NRS), opioid use, satisfaction, incidence of nausea and vomiting, mobility, and discharge times. Results Postoperative pain scores, measured at multiple time points, differed significantly among groups. The SPSIP group reported lower pain scores than both the ESP and control groups (all Bonferroni-adjusted p < 0.05). SPSIP patients used the least opioids, while control patients used the most (3.24+-3.64 vs 6.28+-4.95 vs 9.60+-3.74 mg; one-way ANOVA with Tukey post hoc, p<0.05). No SPSIP patient required additional analgesia, compared to 4 in the ESP group and 14 in the control group (p<0.001). SPSIP patients mobilized earlier (3.76+-3.11 vs 6.44+-4.36 vs 7.80+-3.43 hours; p<0.05) and were discharged sooner (21.88+-8.02 vs 25.08+-3.75 vs 29.52+-8.43 hours; p=0.001). Satisfaction was highest in the SPSIP group (84% "very satisfied" vs 56% vs 20%; p<0.001). Nausea and vomiting rates were comparable across groups (p=0.237). Conclusion Both fascial plane blocks relieved pain after surgery in comparison to the control group. SPSIP had better outcomes in the first 24 hours, including lower pain levels, reduced use of opioids, and faster recovery. SPSIP might be an effective method to manage pain following breast surgery with a single injection, though larger studies are needed to confirm these results. Trial Registration: NCT06611644