Combined Transversus Abdominis Plane and Rectus Sheath Blocks in Open Inguinal Hernia Repair: Protocol for a Double‐Blind Randomized Controlled Trial ( PRO ‐ RSTAP )

BACKGROUND: Inguinal hernia repair is one of the most common surgical procedures worldwide and is frequently performed as day-case surgery. Postoperative pain may delay recovery and occasionally necessitate unplanned hospital admission. Regional anesthesia techniques, including transversus abdominis plane (TAP) and rectus sheath (RS) blocks, have shown promise in improving analgesia. However, their combined efficacy in open inguinal hernia repair has not been established in randomized trials. METHODS: The PRO-RSTAP trial is a prospective, double-blind, four-arm randomized controlled trial conducted at three hospitals in Finland. The study evaluates the individual and combined effects of TAP and RS blocks in adults undergoing elective open inguinal hernia repair. Two hundred patients are randomized equally into four groups: (1) placebo TAP + placebo RS, (2) active TAP + placebo RS, (3) active RS + placebo TAP, and (4) active TAP + active RS. All patients receive standardized sedation and multimodal analgesia, including paracetamol, nonsteroidal anti-inflammatory drugs (NSAIDs), and rescue opioids. The primary outcome is cumulative perioperative opioid consumption from block administration until hospital discharge, expressed as intravenous morphine equivalents. Secondary outcomes include pain scores, conversion to general anesthesia, postoperative nausea and vomiting, time to discharge, and unplanned admissions or emergency visits within 7 days. The planned sample size provides 80% power to detect a clinically meaningful reduction in opioid use (two-sided α = 0.05). Analyses follow the intention-to-treat principle. RESULTS: The first participant was enrolled in September 2025, and the trial is ongoing. No interim efficacy analysis is planned. Safety is monitored continuously throughout the study. CONCLUSION: This randomized controlled trial is designed to determine whether combining TAP and RS blocks improves postoperative analgesia and recovery after open inguinal hernia repair. The results will contribute to evidence-based optimization of regional anesthesia strategies in ambulatory surgery. TRIAL REGISTRATION: EU Clinical Trials Information System (CTIS): 2024-513406-59-00; ClinicalTrials.gov identifier: NCT07423910.