Comparison of serratus posterior superior intercostal plane block versus deep serratus anterior plane block for postoperative analgesia after breast surgery: a prospective randomized study

Background Effective postoperative pain management is essential for recovery after breast surgery. Although regional fascial plane blocks are widely used as part of multimodal analgesia, direct comparative clinical data between serratus posterior superior intercostal plane block (SPSIPB) and serratus anterior plane block (SAPB) are limited. This study compared the analgesic efficacy of SPSIPB and SAPB in patients undergoing unilateral modified radical mastectomy (MRM). Methods This prospective, randomized study included 62 patients with American Society of Anesthesiologists (ASA) physical status I–III scheduled for unilateral MRM. Patients were randomized to either the SPSIPB group (n = 31) or the SAPB group (n = 31). The primary outcome was postoperative pain intensity assessed using the numeric rating scale (NRS). Secondary outcomes included total tramadol consumption during the first 24 hours, intraoperative remifentanil consumption, requirement for rescue analgesia (tenoxicam), postoperative nausea and vomiting (PONV), and patient satisfaction. Opioids were administered via an intravenous patient-controlled analgesia (PCA) device. Results Static NRS scores were significantly higher in the SPSIPB group compared with the SAPB group at postoperative 30 minutes and at the 1st, 4th, and 8th hours (all p < 0.05). No significant differences were observed at the 12th and 24th postoperative hours. Nevertheless, mean NRS scores remained ≤ 4 at all time points in both groups, indicating clinically acceptable analgesia. Total 24-hour tramadol consumption was comparable between the SPSIPB and SAPB groups (76.1 ± 51.1 mg vs. 74.2 ± 44.7 mg; p = 0.875). Intraoperative remifentanil consumption was significantly higher in the SPSIPB group (p = 0.038). There were no significant differences between the groups regarding rescue analgesic requirements, incidence of PONV, or patient satisfaction. Conclusion SPSIPB provides a clinically acceptable postoperative analgesic profile comparable to SAPB within a multimodal analgesia regimen following breast surgery. These findings should not be interpreted as evidence of superiority or equivalence. To better assess the clinical efficacy and potential applications of SPSIPB, more comprehensive and well-designed comparative studies are needed. Trial Registration ClinicalTrials.gov (NCT06436599), retrospectively registered on May 22, 2024.