The efficacy of transcutaneous electronic acupoint stimulation for improving postoperative recovery after gynecologic surgery: A systematic review and meta-analysis.

Gynecological surgery is a common surgical procedure used to treat a variety of conditions, such as abnormal uterine bleeding, uterine fibroids, endometriosis, ovarian cysts, and gynecological cancers. [ 1 ] Despite the benefits of these surgeries, patients often experience significant pain and discomfort during the postoperative period, which can negatively impact their recovery and quality of life. [ 2 ] Many previous studies have attempted various treatment methods to alleviate pain, discomfort, and complications caused by gynecological surgery. For example, misoprostol tablets may be inserted into the vagina to soften the cervix prior to hysteroscopy, or intravenous injection of meperidine may be administered before surgery to effectively dilate the cervix and reduce pain caused by cervical dilation. [ 3 ] The use of small-diameter hysteroscopes or the administration of analgesics or anesthetics (such as tramadol, lidocaine, diclofenac, etc) via oral, intramuscular, cervical, intravenous, or rectal routes can also improve patient pain tolerance and relieve complications to a certain extent. [ 4 – 6 ] Transcutaneous electrical acupoint stimulation (TEAS) aims to stimulate specific acupoints on the body to alleviate various symptoms and enhance overall health. [ 7 ] The primary principle of this technique involves stimulating acupoints on patients to alleviate pain and regulate their bodily functions. [ 8 ] The stimulation of acupoints can induce the release of endogenous opioid-like substances, thereby achieving an analgesic effect. Moreover, it can effectively modify tissue acidity, promote repair in damaged areas, and ultimately alleviate pain caused by non-injurious stimuli. [ 9 , 10 ] The process of TEAS involves several crucial steps, such as selecting appropriate acupoints, placing electrodes correctly, adjusting the stimulation parameters, determining the frequency and duration of treatment, and individualizing the treatment protocol based on the patient response, while also monitoring the progress of the treatment. [ 11 ] Guided by classical acupuncture theories and considering the specific ailment, the acupoint selection is carried out, followed by the strategic placement of electrodes on the skin surface to effectively target these points. [ 12 ] The frequency, pulse width, and intensity of the stimulation can be precisely managed and modified to ensure patients are comfortable and receive the best possible therapeutic outcomes. Since the efficacy of TEAS for improving recovery in patients receiving gynecologic surgery is still controversial, there is a need to pool and analyze the data from published studies. This systematic review and meta-analysis, for the first time, aim to fill this research gap by evaluating the efficacy of TEAS for improving recovery in patients receiving gynecologic surgery.

Conceptualization: Yueping Ge, Jianhong Zheng. Data curation: Jianhong Zheng. Formal analysis: Jianhong Zheng. Investigation: Yueping Ge. Methodology: Yueping Ge, Jianhong Zheng. Software: Yueping Ge. Writing – original draft: Yueping Ge. Writing – review & editing: Jianhong Zheng.

The meta-analysis adhered to the preferred reporting items for systematic reviews and meta-analyses 2020 guidelines. [ 13 ] Ethical approval was unnecessary, as it did not involve direct patient contact or access to personal data; consequently, none was obtained. We conducted a comprehensive search of PubMed, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), WANGFANG DATA, and Chinese Scientific and Technological Journals databases for pertinent publications through March 2023. Search keywords are provided in Supplementary Table S1, http://links.lww.com/MD/J553 . Furthermore, reference lists of chosen articles were manually examined to identify additional germane studies. In this meta-analysis, we included randomized controlled trials if they evaluated the efficacy of TEAS for improving recovery in patients receiving gynecologic surgery, with a minimum sample size of 10. Exclusion criteria encompassed duplicate articles, abstracts without full text, editorials, letters, case reports, reviews, meta-analyses, and irrelevant titles or abstracts. Studies presenting incomplete or ambiguous data precluding outcome calculation were also excluded. For overlapping datasets, we included only the most recent publication. Two investigators independently assessed article titles and abstracts according to the established inclusion and exclusion criteria. Subsequently, they examined the full text to verify study eligibility. Disagreements were resolved through discussion until a consensus was reached. Utilizing the updated Cochrane Risk of Bias Tool for randomized trials, 2 independent researchers evaluated the quality levels of the included studies (RoB 2.0). [ 14 , 15 ] Factors such as random sequence generation (selection bias), allocation concealment (selection bias), blinding of participants and personnel (performance bias), blinding of outcome assessment (detection bias), incomplete data (attrition bias), selective reporting (reporting bias), and other biases were meticulously examined by both reviewers. In case of any discrepancies, a third researcher was consulted for resolution. Two researchers independently performed data extraction for each included article, encompassing author, year, country, comparison, number of patients, disease, outcome, electrodes, electrode placement sites, duration of each session, and TEAS prescription. Discrepancies among the researchers were resolved through discussion, ultimately reaching a consensus. Outcome measures encompassed postoperative nausea, postoperative vomiting, visual analogue scale (VAS), time to first bowel movement, and time to first flatus. Postoperative nausea refers to the sensation of unease or discomfort in the stomach, often accompanied by an urge to vomit, that occurs following a surgical procedure. Postoperative vomiting, on the other hand, is the act of forcefully expelling the contents of the stomach through the mouth after a surgical procedure. The VAS score is a simple measurement tool used to assess pain, with higher values signifying increased pain levels. Time to first bowel movement and time to first flatus refers to the duration between a surgical procedure and the patient first postoperative bowel movement and first flatus. Both outcomes are crucial for assessing gastrointestinal function and recovery following surgery. Generally, shorter durations to first bowel movement or flatus suggest a faster return to normal bowel function. For this analysis, continuous outcomes were evaluated using the weighted mean difference (WMD), while binomial outcomes were assessed with the risk ratio (RR). Corresponding 95% confidence intervals (CIs) were also calculated to provide an estimation of the range. To assess the heterogeneity among the included studies, Cochran I 2 and Q statistics were employed. Based on I 2 values, heterogeneity was categorized as low (25%), moderate (50%), or high (75%). [ 16 ] A fixed-effects model was employed when the I 2 value was below 50%; otherwise, a random-effects model was utilized. In cases of substantial heterogeneity ( I 2 ≥ 50%), leave-one-out sensitivity analyses were conducted to identify potential sources of heterogeneity and evaluate the robustness of the results. Publication bias, which may arise when studies with positive or significant results are more likely to be published, was evaluated using Egger test. [ 17 ] For all statistical tests excluding heterogeneity ( P < .10), a 2-tailed P value below .05 was considered statistically significant. Statistical analyses were conducted using Stata 15.1 software.

The initial search yielded 1357 publications. Of these, 430 were identified as duplicates, and 907 did not meet the eligibility criteria, thus were excluded from further consideration. A thorough evaluation of the full texts of the remaining 20 articles resulted in the exclusion of an additional 8 studies, either due to insufficient data (n = 5) or irrelevance of the full text (n = 3). Ultimately, 12 randomized controlled trials assessing the efficacy of TEAS in enhancing recovery for patients undergoing gynecologic surgery were included in the analysis. [ 18 – 29 ] Figure 1 illustrated the preferred reporting items for a systematic review and meta-analysis flow diagram in the study selection process. Preferred reporting items for a systematic review and meta-analysis (PRISMA) flow diagram illustrating the study selection process. The 12 eligible studies encompassed a total of 1510 patients and were all randomized controlled trials conducted in China. The study characteristics were concisely summarized in Table 1 , while Table 2 provided an overview of the transcutaneous electronic acupoint stimulation parameters. The number of patients in each study ranged from 30 to 150.The mean age of patients ranged from 33.6 to 67.6 years. The number of electrodes used in the studies varied, with some studies using 2 electrodes and others using up to 6 electrodes. Some common acupuncture points used for electrode placement included Neiguan (PC6), Zusanli (ST36), Hegu (LI4), Sanyinjiao (SP6), Liangqiu (ST34), and points at the levels of T10-L1, S2-S4, and 1 transverse finger above the pubic symphysis. Electrodes were also placed in the peri-incisional area in 1 study. The stimulation frequency ranged from 1 to 100 Hz, and the duration for each session ranged from 30 to 167 minutes. The intensity of stimulation was generally between 2 and 20 mA, but some studies recommended adjusting it based on the patient tolerance. The study characteristics of the included studies. ①, postoperative nausea; ②, postoperative vomiting; ③, visual analogue scale (VAS); ④, time to first bowel movement; ⑤, time to first flatus. NA = not available, TEAS = transcutaneous electronic acupoint stimulation. Transcutaneous electronic acupoint stimulation parameters. NA = not available, TEAS = transcutaneous electronic acupoint stimulation. Figure 2 displayed the risk of bias for each study, as determined by the RoB 2.0. Overall, the included studies exhibited acceptable quality. Risk of bias of the included studies using the revised Cochrane risk of bias tool (RoB 2.0) for randomized trials. Eight studies with 930 patients assessed postoperative nausea. Considering the high heterogeneity ( I 2 = 59.9%, P = .02), the random-effect model was performed. Meta-analysis found that TEAS significantly reduced the risk of postoperative nausea (RR: 0.60, 95% CI: 0.43–0.83, P = .002) compared to the conventional group (Fig. 3 ). Sensitivity analysis by excluding data from Yin et al demonstrated no heterogeneity ( I 2 = 0%), indicating it may be the source of heterogeneity. However, all of the sensitivity analysis results were consistent with the overall results, which further proved the robustness of the results (Supplementary Fig. S1, http://links.lww.com/MD/J554 ). No evidence of publication bias was detected through the application of Egger test ( P = .29). Forest plot of transcutaneous electronic acupoint stimulation (TEAS) versus conventional group of postoperative nausea in patient receiving gynecologic surgery. Eight studies with 930 patients assessed white blood cell counts. Considering the low heterogeneity ( I 2 = 13.8%, P = .32), the fixed-effect model was performed. Meta-analysis found that TEAS significantly reduced the risk of postoperative vomiting (RR: 0.54, 95% CI: 0.43–0.67, P < .001) compared to the conventional group (Fig. 4 ). All of the sensitivity analysis results were consistent with the overall results, which further proved the robustness of the results (Supplementary Fig. S2, http://links.lww.com/MD/J555 ). No evidence of publication bias was detected through the application of Egger test ( P = .21). Forest plot of transcutaneous electronic acupoint stimulation (TEAS) versus conventional group of postoperative vomiting in patient receiving gynecologic surgery. Eight studies with 1059 patients assessed white blood cell counts. Considering the high heterogeneity ( I 2 = 92.5%, P < .001), the random-effect model was performed. Meta-analysis found that TEAS significantly reduced the VAS score (WMD: −0.47, 95% CI: −0.76 to −0.17, P = .002) compared to the conventional group (Fig. 5 ). Sensitivity analysis showed stable results with no source of heterogeneity identified. However, all of the sensitivity analysis results were consistent with the overall results, which further proved the robustness of the results (Supplementary Fig. S3, http://links.lww.com/MD/J556 ). No evidence of publication bias was detected through the application of Egger test ( P = .22). Forest plot of transcutaneous electronic acupoint stimulation (TEAS) versus conventional group of visual analogue scale (VAS) score in patient receiving gynecologic surgery. Three studies with 316 patients assessed white blood cell counts. Considering the low heterogeneity ( I 2 = 12.8%, P = .32), the fixed-effect model was performed. Meta-analysis found that TEAS significantly reduced the time to first bowel movement (WMD: −18.43, 95% CI: −20.87 to −15.99, P < .001) compared to the conventional group (Fig. 6 ). No evidence of publication bias was detected through the application of Egger test ( P = .35). Forest plot of transcutaneous electronic acupoint stimulation (TEAS) versus conventional group of the time to first bowel movement in patient receiving gynecologic surgery. Three studies with 316 patients assessed white blood cell counts. Considering the high heterogeneity ( I 2 = 63.7%, P = .06), the random-effect model was performed. Meta-analysis found that TEAS significantly reduced the time to first flatus (WMD: −8.98, 95% CI: −12.46 to −5.51, P < .001) compared to the conventional group (Fig. 7 ). Sensitivity analysis by excluding data from Wang et al demonstrated no heterogeneity ( I 2 = 0%), indicating it may be the source of heterogeneity. All of the sensitivity analysis results were consistent with the overall results, which further proved the robustness of the results (Supplementary Fig. S4, http://links.lww.com/MD/J557 ). No evidence of publication bias was detected through the application of Egger test ( P = .79). Forest plot of transcutaneous electronic acupoint stimulation (TEAS) versus conventional group of the time to first flatus in patient receiving gynecologic surgery.

TEAS has been shown to increase oxygen delivery to cells, boost metabolic rate, and reduce inflammation. Also, it helps restore intestinal peristalsis, eases abdominal pressure, and encourages bowel movements. [ 30 – 33 ] The efficacy of TEAS for postoperative recovery in patient receiving gynecological surgery remains unclear. Some studies have reported significant reductions in postoperative pain, nausea, and vomiting, while others have found no significant differences between TEAS and conventional treatments. A meta-analysis can contribute to resolving these issues by systematically synthesizing and analyzing the available evidence from a range of randomized controlled trials investigating the efficacy of TEAS for postoperative recovery after gynecologic surgery. To the best of our knowledge, this is the first systematic review and meta-analysis to evaluate the efficacy of TEAS for improving postoperative recovery after gynecologic surgery. Our analysis included 12 randomized controlled trials comprising 1510 patients, and found that TEAS significantly reduced the risk of postoperative nausea, postoperative vomiting, and VAS score, as well as shortened the time to first bowel movement and first flatus compared to the conventional group. These results are consistent with some previous studies that have investigated the use of TEAS for postoperative recovery. In 2021, a meta-analysis by Zheng et al [ 34 ] showed that TEAS therapy was significantly more effective than control interventions in reducing the incidence of postoperative nausea and vomiting after gynecologic surgery (RR: 0.52, 95% CI: 0.31–0.88, P = .02). However, while Zheng et al included a total of 10 articles, only 2 of them used TEAS as the treatment group, which limited their ability to draw definitive conclusions about the efficacy of TEAS. In contrast, our meta-analysis included a larger number of studies (12 in total) and included additional outcome measures such as VAS score, time to first bowel movement, and time to first flatus. This allowed us to more comprehensively and objectively evaluate the treatment effect of TEAS. Another meta-analysis conducted by Liu et al [ 35 ] in 2022 found that low-frequency electrical stimulation can significantly improve therapeutic effect (defined as the absence of acute urinary retention within 6 hours of removing the urinary catheter and the ability to urinate normally after hysterectomy), reduced residual urine volume, and catheter retention time in cervical cancer patients who underwent radical hysterectomy. We both have the same limitation by including only studies from China, but they mainly focused on outcomes related to the urinary system, which differs from our outcome measures. In the current meta-analysis, there was high heterogeneity in postoperative nausea ( I 2 = 59.9%, P = .02), VAS score ( I 2 = 92.5%, P < .001), and the time to first flatus ( I 2 = 63.7%, P = .06). We assessed the heterogeneity sources among the studies through a leave-one-out sensitivity analysis. Regarding postoperative nausea, the exclusion of data from Yin et al yielded no heterogeneity ( I ²=0%), suggesting it as the potential origin of heterogeneity. Similarly, for the time to first flatus, the absence of Wang et al data demonstrated no heterogeneity ( I ²=0%), indicating that it may be the source of heterogeneity. Conversely, sensitivity analysis for VAS score showed stable results with no source of heterogeneity identified, it may be attributed to disparities in patient populations, methodologies, and study designs. However, all of the sensitivity analysis results were consistent with the overall results, which further proves the robustness of the result. We didn’t conduct meta-regression analysis to explore the source of heterogeneity as the number of included studies is <10. [ 36 ] When considering the publication bias, we conducted Egger test and found that no publication bias was observed for any of the results. Some limitations need to be mentioned. Firstly, the patients included in the study are all from China, and the efficacy of TEAS in Asians cannot be directly extrapolated to other races, more studies with participants from other races are needed. Secondly, despite our efforts to minimize heterogeneity by only including randomized controlled studies and using strict inclusion criteria, the included studies still differed in terms of patient characteristics, surgical procedures, and TEAS parameters. This heterogeneity may have contributed to the variability in the effect sizes and made it difficult to draw definitive conclusions. Thirdly, most of the included studies had short-term follow-up periods, ranging from hours to days. Therefore, we could not assess the long-term effects of TEAS on postoperative recovery outcomes, such as chronic pain, quality of life, or functional status.

Based on the pooled results, our findings suggested that TEAS may improve postoperative recovery following gynecologic surgery. However, to confirm these results, larger randomized controlled trials encompassing a more diverse range of patient populations are urgently required.