ObjectiveCurrently, the primary surgical treatment for pseudomyxoma peritonei (PMP) is cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). The perioperative period is frequently accompanied by severe pain. Erector spinae plane block (ESPB) can enhance analgesia for abdominal surgery. The purpose of this study was to compare the analgesic effects of bilateral multiple-injection ESPB in patients with PMP.MethodsFifty patients with PMP were randomly divided into two groups: the ESPB combined with general anesthesia group (Group E) and the general anesthesia alone group (Group C). Prior to the induction, patients in Group E underwent ESPB at the T7 and T11 levels. The primary outcome was the visual analog scale (VAS) scores during rest at 6 h post-extubation. Secondary outcomes included intraoperative and postoperative opioid consumption, time for first rescue analgesia, frequency distribution of rescue analgesia, incidence of nausea and vomiting, adverse events associated with ESPB.ResultsThe Visual Analogue Scale (VAS) scores in Group E were significantly lower compared to Group C at immediate post-extubation (1.6 ± 0.9 vs. 2.4 ± 1.2, P = 0.008), and at 2 (1.9 ± 1.2 vs. 3.2 ± 1.1, P < 0.001), 4 (2.4 ± 1.5 vs. 3.7 ± 1.0, P = 0.001), and 6 h (2.7 ± 1.1 vs. 3.8 ± 1.4, P = 0.004) post-extubation during rest. Similarly, the VAS scores in Group E were significantly lower than those in Group C at immediate post-extubation (3.0 ± 1.4 vs. 4.6 ± 1.2, P < 0.001), and at 2 (3.8 ± 1.7 vs. 4.9 ± 1.4, P = 0.019), 4 (3.5 ± 1.3 vs. 5.3 ± 1.5, P < 0.001), and 6 h (3.9 ± 1.8 vs. 4.9 ± 1.3, P = 0.004) post-extubation during movement. In Group E, the intraoperative remifentanil administration (2319.3 ± 1089.5 vs. 2984.6 ± 796.1, P = 0.017) and the amount of rescue analgesia within 2 h post-extubation (0 vs. 4, P = 0.037) were significantly less than in Group C, and the first rescue analgesia time was shorter as well (231.4 ± 147.5 vs. 668.8 ± 416.7, P < 0.001).ConclusionCompared to general anesthesia alone, bilateral multiple-injection ESPB with 0.2% ropivacaine can enhance analgesia and reduce opioid administration in patients with PMP. However, the duration of analgesia with ESPB is relatively short due to the low concentration of the local anesthetic used.Trial registrationChinese Clinical Trial Registry, ChiCTR2300069504, 20/03/2023.