Effect of Perineural Dexamethasone as an Adjuvant to Ropivacaine in Rectus Sheath Block for Radical Cystectomy: A Randomized Controlled Trial

Background/Objectives: Radical cystectomy via midline laparotomy is associated with significant postoperative pain, often necessitating substantial opioid use, which may impair immune function and delay recovery. The rectus sheath block (RSB) is commonly employed as part of multimodal analgesia to improve postoperative pain control; however, its duration is limited with single-injection techniques. Dexamethasone has increasingly been used as a perineural adjuvant to prolong peripheral nerve block effects and enhance analgesia. This study aimed to evaluate the analgesic efficacy of adding perineural dexamethasone to RSB in patients undergoing radical cystectomy. Methods: In this randomized controlled trial, 52 adult patients scheduled for radical cystectomy were randomly assigned to receive ultrasound-guided bilateral RSB with either 0.25% ropivacaine alone or 0.25% ropivacaine combined with 4 mg of dexamethasone per side following skin closure. Postoperative pain intensity was assessed using a numeric rating scale (NRS) at 3, 6, 12, 18, 24, and 48 hours postoperatively. Cumulative intravenous patient-controlled analgesia (IV-PCA) fentanyl consumption and the incidence of rebound pain—defined as an increase in NRS from ≤ 3 to ≥ 7 within 24 hours after block resolution—were also recorded. Results: The addition of dexamethasone significantly reduced cumulative fentanyl consumption. Pain scores were consistently lower in the dexamethasone group compared to the ropivacaine-only group at all time points, except 3 hours postoperatively. The incidence of rebound pain was also markedly lower in the dexamethasone group. Conclusions: Perineural dexamethasone as an adjuvant to RSB provides effective, prolonged analgesia, reduces opioid requirements, and lowers the incidence of rebound pain in patients undergoing radical cystectomy.