Perioperative transcutaneous auricular vagus nerve stimulation for the prevention of postoperative nausea and vomiting after gynecologic laparoscopic surgery: protocol for a randomized, double-blind, sham-controlled trial

BackgroundPostoperative nausea and vomiting (PONV) remains a common and distressing complication after gynecologic laparoscopic surgery, despite the use of multimodal antiemetic prophylaxis. Transcutaneous auricular vagus nerve stimulation (taVNS) is a noninvasive neuromodulation technique that targets vagal afferents in the external ear and may modulate brainstem and autonomic pathways involved in nausea and vomiting. This randomized trial will evaluate taVNS as an adjunctive, nonpharmacological strategy for preventing PONV in women undergoing gynecologic laparoscopic surgery. MethodsThis single-center, prospective, randomized, double-blind, sham-controlled, parallel-group superiority trial will enroll 146 adult women undergoing elective gynecologic laparoscopic surgery under general anesthesia. Participants will be randomly assigned in a 1:1 ratio to receive active taVNS or sham stimulation, with randomization stratified by Apfel risk score ([≤]2 vs [≥]3). Participants will receive two 30-minute stimulation sessions: one beginning 30 minutes before induction of anesthesia and the other beginning 30 minutes after arrival in the post-anesthesia care unit. The primary outcome is the proportion of participants experiencing PONV during the first 48 hours after surgery, according to the prespecified definition. Secondary outcomes include nausea severity, time to the first PONV episode, the number of vomiting or retching episodes, rescue antiemetic use, postoperative pain intensity, cumulative opioid consumption expressed as morphine milligram equivalents, Quality of Recovery-15 scores at 24 and 48 hours, and prespecified measures of gastrointestinal recovery. The primary analysis will follow the intention-to-treat principle. A per-protocol analysis and prespecified missing-data sensitivity analyses will also be performed. ConclusionsThis trial will evaluate the efficacy and safety of perioperative taVNS for PONV prevention in women undergoing gynecologic laparoscopic surgery. If effective, taVNS may represent a feasible nonpharmacological adjunct to standard antiemetic prophylaxis and may be incorporated into enhanced recovery after surgery pathways. Trial registrationChinese Clinical Trial Registry, ChiCTR2600115965; registered on 4 January 2026.