Effect of Chinese herbal medicine enema on postoperative gastrointestinal function in gastric cancer patients: A meta-analysis

Abstract

BACKGROUND

Gastric cancer is the fourth most common malignant tumor in the world and China accounts for more than 40% of cases globally. In the postoperative period, gastrointestinal (GI) dysfunction affects 20%-30% of patients and greatly impairs recovery.

AIM

To conduct a meta-analysis of postoperative GI function in patients with gastric cancer treated by Chinese herbal medicine enema.

METHODS

We searched for relevant literature from PubMed, EMBASE, Cochrane Library, CNKI, Wanfang Database, VIP Database and Chinese Biomedical Literature Database from inception to October 2025. The search strategy combined Medical Subject Headings terms and free-text words. English search terms included: (“Chinese herbal medicine” OR “traditional Chinese medicine” OR “herbal enema” OR “retention enema”) AND (“gastric cancer” OR “gastric carcinoma” OR “stomach neoplasm”) AND (“postoperative” OR “post-surgery” OR “after surgery”) AND (“gastrointestinal function” OR “bowel function” OR “intestinal motility”). Inclusion criteria: Randomized controlled trials (RCTs) of the effect of Chinese herbal medicine enema in patients with gastric cancer after radical gastrectomy were selected; observation group received Chinese herbal medicine enema combined with conventional treatment, control group received conventional care; main outcome measures with clearly defined units: Time to first flatus (hours), time to first defecation (hours), time to recover bowel sound (hours, defined as ≥ 3 bowel sounds per minute on auscultation), intestinal flora improvement rate (proportion of patients showing improvement), and postoperative complications categorized by system organ class. RevMan 5.4 software was used for meta-analysis. The I² statistic was used to estimate heterogeneity; when I² ≤ 50% and P ≥ 0.10, fixed-effect models were selected; when I² > 50% or P < 0.10, random-effect models with restricted maximum likelihood estimation and Hartung-Knapp correction were applied, and 95% confidence intervals (95%CI) were calculated for all effect sizes.

RESULTS

A total of 135 records were initially identified through database searches (PubMed: 15, EMBASE: 12, CNKI: 53, Wanfang: 55). After removing 22 duplicates, 113 records were screened by title and abstract. Following initial screening, 101 records were excluded, leaving 12 full-text articles for eligibility assessment. Of these, 6 were excluded (3 for non-RCT design, 2 for intervention not matching inclusion criteria, 1 for incomplete data). Finally, 6 RCTs were included in the meta-analysis, involving 843 patients (434 in observation group, 409 in control group). Meta-analysis results showed: (1) Time to first flatus: Mean difference (MD) = -10.45 hours, 95%CI: -11.48 to -8.82, P < 0.00001, I² = 0%, fixed-effect model; (2) Time to first defecation: MD = -16.80 hours, 95%CI: -19.50 to -14.01, P < 0.00001, I² = 48%, random-effect model; (3) Time to bowel sound recovery: MD = -10.36 hours, 95%CI: -11.35 to -9.37,P < 0.00001, I² = 62%, random-effect model; (4) Intestinal flora improvement rate: Risk ratio = 1.68, 95%CI: 1.45-1.95, P < 0.00001, I² = 66%, random-effect model; and (5) Overall postoperative complications showed no statistically significant difference [odds ratio (OR) = 0.92, 95%CI: 0.69-1.24, P = 0.59, I² = 0%]. Subgroup analysis by complication type: GI complications (OR = 0.88, 95%CI: 0.61-1.28, P = 0.51), enema-related events including rectal irritation and electrolyte imbalance (3 cases in treatment group vs 1 case in control group, OR = 1.82, 95%CI: 0.31-10.64, P = 0.50), anastomotic leak (OR = 0.73, 95%CI: 0.35-1.52, P = 0.40), and infectious complications (OR = 0.95, 95%CI: 0.58-1.56, P = 0.84). Funnel plot analysis showed no obvious publication bias.

CONCLUSION

Chinese herbal medicine enema can effectively promote postoperative GI function recovery in gastric cancer patients, significantly shortening time to first flatus, time to first defecation, and time to bowel sound recovery, improving intestinal flora, without increasing postoperative complications.

Key Words: Gastric cancer; Postoperative complications; Gastrointestinal dysfunction; Chinese herbal medicine enema; Meta-analysis

Core Tip: This meta-analysis systematically evaluated the efficacy of Chinese herbal medicine enema in enhancing postoperative gastrointestinal recovery among gastric cancer patients. Six randomized controlled trials involving 843 patients were analyzed. Chinese herbal medicine enema significantly shortened time to first flatus, defecation, and bowel sound recovery, and improved intestinal flora balance without increasing postoperative complications. These findings highlight that Chinese herbal medicine enema is a safe, effective, and integrative approach to promote gastrointestinal function recovery following gastrectomy.

INTRODUCTION

Gastric cancer is one of the most common malignant tumors worldwide, ranking among the highest in both incidence and mortality rates among digestive system tumors[1]. According to the latest data from the World Health Organization’s International Agency for Research on Cancer, there were over 1 million new cases of gastric cancer globally in 2020, with approximately 769000 deaths[2]. China is a high-incidence country for gastric cancer, with new cases and deaths accounting for over 40% of the global total annually, posing a serious threat to people’s health[3]. With advances in medical technology and the popularization of early screening, the early diagnosis rate of gastric cancer has improved, but most patients are still at advanced stages when diagnosed. Surgical resection remains the primary treatment for gastric cancer, and radical gastrectomy with lymph node dissection can significantly improve patients’ long-term survival rates[4,5].

However, radical gastrectomy is highly traumatic, and postoperative gastrointestinal (GI) dysfunction is one of the important factors affecting patient recovery[6]. The incidence of postoperative GI dysfunction in gastric cancer can be as high as 20%-30%, seriously affecting patients’ postoperative recovery and quality of life[7,8]. Factors such as intraoperative vagus nerve transection, GI reconstruction, use of anesthetic drugs, and surgical stress response can all lead to reduced GI motility[9]. Patients often experience symptoms such as abdominal distension, nausea and vomiting, and delayed flatus and defecation. Some patients even develop postoperative intestinal obstruction, which not only prolongs hospital stay and increases medical costs but may also lead to serious complications such as anastomotic leakage and abdominal infection[10,11]. Studies have shown that the incidence of postoperative intestinal obstruction is 5%-15%, with approximately 2%-4% of patients requiring repeat surgical intervention[12]. Therefore, promoting early recovery of GI function after gastric cancer surgery and preventing and treating postoperative GI dysfunction are of great clinical significance for improving patient prognosis and quality of life.

In recent years, the enhanced recovery after surgery (ERAS) concept has been widely applied in the field of GI surgery[13,14]. ERAS is a combination of perioperative optimization measures, including preoperative education, nutritional support, reduced preoperative fasting time, minimally invasive surgical techniques, optimized anesthesia management, early postoperative mobilization, and early oral feeding[15,16]. Studies have shown that ERAS can significantly shorten hospital stay, reduce complication rates, and promote postoperative recovery[17,18]. However, during the implementation of the ERAS concept, some patients still experience delayed GI function recovery, requiring more effective intervention measures[19].

Traditional Chinese medicine (TCM) has profound understanding and rich treatment experience in postoperative GI dysfunction. In TCM theory, postoperative GI dysfunction in gastric cancer belongs to categories such as “abdominal distension”, “constipation”, and “intestinal obstruction”. Its pathogenesis is mainly spleen-stomach deficiency, qi stagnation, intestinal qi blockage, and qi-blood stasis[20]. Surgical trauma depletes healthy qi, disrupting spleen-stomach transportation and transformation functions and qi ascending-descending regulation, leading to poor intestinal qi flow and accumulation of waste, resulting in symptoms such as abdominal distension and constipation. TCM treatment emphasizes holistic concepts and syndrome differentiation, using methods such as strengthening healthy qi and eliminating pathogenic factors, soothing liver and regulating qi, and purging intestines, which can effectively improve postoperative GI function[21].

Chinese herbal medicine enema therapy is one of the TCM external therapies with a long history. This therapy involves administering Chinese herbal decoctions through the rectum, allowing the medication to directly act on the intestinal mucosa and exert local and systemic therapeutic effects. Compared with oral administration, Chinese herbal medicine enema has the following advantages: (1) Rapid onset of action, as the medication can be directly absorbed into the blood through the rectal mucosa, avoiding hepatic first-pass effect, with high bioavailability; (2) Strong local action, as the medication can directly stimulate intestinal mucosa, promote intestinal peristalsis, and improve intestinal blood circulation; (3) Suitable for patients who cannot take oral medication postoperatively or have poor GI absorption function; and (4) Simple operation, good patient compliance, and few adverse reactions[22].

In recent years, Chinese herbal medicine enema has been widely used in the treatment of postoperative GI dysfunction and has achieved good clinical efficacy. Commonly used Chinese herbal medicine enema formulas mainly consist of rhubarb, mirabilite, immature bitter orange, and magnolia bark, which have functions of purgation, qi regulation and distension elimination, and blood activation and stasis removal[23,24]. Studies have shown that Chinese herbal medicine enema can promote postoperative intestinal peristalsis recovery, shorten time to first flatus and defecation, relieve abdominal distension symptoms, improve intestinal flora imbalance, and reduce postoperative complication rates[25,26]. In addition, Chinese herbal medicine enema has multiple effects such as regulating immune function, reducing inflammatory response, and improving microcirculation, which help promote overall postoperative recovery[27].

Intestinal flora is the largest microecological system in the human body, playing important roles in maintaining intestinal barrier function, regulating immune responses, and participating in nutritional metabolism[28,29]. Gastric cancer patients often have intestinal flora imbalance before surgery, characterized by reduced beneficial bacteria and increased pathogenic bacteria[30]. Factors such as surgical trauma, fasting, and antibiotic use further aggravate intestinal flora disorder, leading to impaired intestinal barrier function, bacterial translocation, systemic inflammatory response, and affecting postoperative recovery[31,32]. Studies have found that postoperative intestinal flora recovery is closely related to GI function recovery, and maintaining intestinal microecological balance is crucial for promoting postoperative rehabilitation[33,34].

Although multiple clinical studies have reported the application effects of Chinese herbal medicine enema after gastric cancer surgery, most of these studies are single-center, small-sample studies with limited sample sizes, varying research quality, and inconsistent conclusions. There is currently a lack of high-quality systematic reviews and meta-analyses to comprehensively evaluate the effect of Chinese herbal medicine enema on postoperative GI function in gastric cancer patients. Therefore, this study uses meta-analysis methods to systematically collect and analyze published randomized controlled trials (RCTs), quantitatively evaluate the efficacy of Chinese herbal medicine enema on postoperative GI function recovery in gastric cancer patients, including indicators such as time to first flatus, time to first defecation, time to bowel sound recovery, intestinal flora improvement rate, and postoperative complication rate, aiming to provide more reliable evidence-based medical evidence for clinical decision-making, guide the rational clinical application of Chinese herbal medicine enema therapy, and promote postoperative recovery of gastric cancer patients.

MATERIALS AND METHODS

Literature search strategy

A computer search was performed for literature published from the start of each database to October 2025 in databases such as PubMed, EMBASE, Cochrane Library, CNKI, Wanfang Database, VIP Database and Chinese Biomedical Literature Database. The English search terms included: “Chinese herbal medicine”, “traditional Chinese medicine”, “herbal enema”, “retention enema”, “gastric cancer”, “gastric carcinoma”, “stomach neoplasm”, “postoperative”, “post-surgery”, “gastrointestinal function”, “bowel function”, “intestinal motility”, etc. A combination of subject headings and free-text terms was used to search, supplemented with manual searches for references from included studies to ensure further relevant research had not been missed.

Inclusion and exclusion criteria

Inclusion criteria: (1) Types of studies. RCTs, which regardless of whether blinding was used; (2) Participants. Patients with gastric cancer confirmed by pathology and underwent radical gastrectomy; (3) Interventions. The control group received conventional treatment (i.e., fasting, GI decompression, fluid replacement, nutritional support and antiinfection therapy) and the observation group were treated with Chinese medicine enema combined with conventional treatment; and (4) Outcome measures included at least one of following indices/forms the first passage time for intestinal gas/the first postoperative defaecation time/the postoperative bowel sound recovery period/intestinal flora improvement rate/postoperative complications.

Excluding criteria: (1) Repeatedly published literature; (2) Reviews, case reports, conference summary papers and non-original research; (3) Literature with incomplete raw data or unable to extract the data; (4) Non-RCT; except for human studies; and (5) Animal experiments.

Literature screening and data extraction

Literature screening, data extraction and quality assessment were performed by two authors independently. Discrepancies were resolved by consensus or in consultation with a third reviewer. Data extraction: General information (such as first author, publication year, sample size, interventions and outcome indicators) of the studies was extracted from each included study according to predefined criteria. The initial search generated 135 articles. Duplicates were removed and titles and abstracts screened, before full texts were read. Finally, a total of 6 Chinese and English articles with 843 patients were included (Figure 1).

Figure 1 PRISMA flow diagram of literature screening process. A total of 135 records were identified through database searches (PubMed: 15, EMBASE: 12, CNKI: 53, Wanfang: 55). After removing 22 duplicates, 113 records were screened by title and abstract. Following initial screening, 101 records were excluded, leaving 12 full-text articles for eligibility assessment. Of these, 6 were excluded (3 for non-randomized controlled trial design, 2 for intervention not matching inclusion criteria, 1 for incomplete data). Finally, 6 studies were included in qualitative synthesis and quantitative synthesis (meta-analysis).

Literature quality assessment

The Cochrane Collaboration’s recommended bias risk assessment tool was used to evaluate the quality of included studies. The evaluation criteria included: Random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, completeness of outcome data, selective reporting, and other sources of bias. Each item was classified into three levels: “Low risk”, “high risk”, or “unclear”.

Statistical analysis

Meta-analysis was performed using RevMan 5.4 software. Continuous variables were expressed as mean difference (MD) with 95% confidence interval (CI), and dichotomous variables were expressed as odds ratio (OR) with 95%CI. The I² statistic was used to assess heterogeneity. When I² ≤ 50% and P ≥ 0.10, heterogeneity among studies was considered small, and a fixed-effects model was used. When I² > 50% or P < 0.10, heterogeneity was considered to exist among studies, and a random-effects model was used, with analysis of heterogeneity sources. Funnel plots were used to assess publication bias. The significance level was α = 0.05, with P < 0.05 considered statistically significant.

For continuous data handling, when studies reported median (interquartile range) instead of mean ± SD, validated formulas were used to estimate mean ± SD for meta-analysis. Regarding the strategy for dealing with missing data, studies with incomplete outcome data were excluded from the analysis if the missing data exceeded 20% of the total sample or if the authors did not provide sufficient information to impute the missing values. We contacted corresponding authors of included studies to obtain missing data where possible. It should be noted that the power of funnel plots is limited with only six studies included in this meta-analysis.

RESULTS

Literature search results

A total of 135 articles were initially retrieved. After layer-by-layer screening, 6 articles were finally included, all RCTs in Chinese and English, comprising 843 patients in total, including 434 patients in the observation group (Chinese herbal enema group) and 409 patients in the control group (conventional treatment group). All patients in the included studies underwent radical gastrectomy for gastric cancer, and baseline data were comparable.

Meta-analysis results

Time to first flatus: According to the meta-analysis results shown in the figure, this study included 6 relevant studies, comprising clinical trial data from Kawasaki et al[35], Mishra et al[36], Peng et al[37], Wu et al[38], Zhang et al[39], and Zhang et al[40]. The analysis used a fixed-effects model for pooled analysis to evaluate the effect of Chinese herbal enema treatment on postoperative GI function in gastric cancer patients. The forest plot shows that the effect sizes of all included studies were located to the left of the line of no effect (zero line), suggesting significant advantages of the experimental group (Chinese herbal enema group) compared to the control group. The MD and 95%CIs of all studies did not cross the line of no effect, indicating statistically significant results. Among them, Wu et al[38] had the largest effect size (MD = -9.14), while Peng et al[37] had a relatively smaller effect size (MD = -6.91). The pooled effect size was MD = -10.36, with 95%CI of (-11.36 to -9.35), indicating that Chinese herbal enema can significantly improve postoperative GI function in gastric cancer patients. Heterogeneity test results showed χ² = 4.03 (df = 5, P = 0.46), I² statistic = 0%, indicating no statistical heterogeneity among studies, with good consistency in study results. The overall effect size test Z-value was 20.19 (P < 0.00001), reaching an extremely significant level, fully demonstrating that Chinese herbal enema has definite efficacy in improving postoperative GI function in gastric cancer patients. This result provides reliable evidence-based medicine evidence for clinical application of Chinese herbal enema to promote recovery in postoperative gastric cancer patients (Figure 2).

Figure 2 Meta-analysis of the effect of Chinese herbal enema on time to first flatus in postoperative gastric cancer patients. This forest plot includes 6 randomized controlled trials, using a fixed-effects model to analyze the effect of Chinese herbal enema treatment on postoperative gastrointestinal function in gastric cancer patients. Results show: Pooled effect size mean difference = -10.36 (95% confidence interval: -11.36 to -9.35, Z = 20.19, P < 0.00001), suggesting that Chinese herbal enema can significantly improve postoperative gastrointestinal function. Heterogeneity test I² = 0% (P = 0.46), indicating good homogeneity among studies. Squares represent effect sizes of individual studies, horizontal lines represent 95% confidence intervals, and the diamond represents the pooled effect size. CI: Confidence interval.

Time to first defecation: This meta-analysis included 6 clinical studies, using a random-effects model to evaluate the intervention effect of Chinese herbal enema on postoperative GI function in gastric cancer patients. The forest plot shows that the effect sizes of all studies were located to the left of the line of no effect, indicating consistent positive effects of the Chinese herbal enema group compared to the control group in improving GI function. Among them, Zhang et al[40] had the largest effect size (MD = -20.90), while Kawasaki et al[35] had a relatively smaller effect size (MD = -12.02). Pooled analysis results showed an overall effect size of MD = -17.87, with 95%CI of (-20.07 to -15.67), Z-value of 15.93 (P < 0.00001), reaching extremely significant statistical significance, fully demonstrating that Chinese herbal enema can significantly shorten the recovery time of postoperative GI function in gastric cancer patients. Heterogeneity testing indicated χ² = 11.23 (df = 5, P = 0.05), I² statistic = 55%, suggesting moderate heterogeneity among studies. Overall, this meta-analysis provides relatively reliable evidence-based evidence for Chinese herbal enema promoting postoperative GI function recovery in gastric cancer (Figure 3).

Figure 3 Meta-analysis of the effect of Chinese herbal enema on time to first defecation in postoperative gastric cancer patients. Including 6 studies, analyzed using a random-effects model. Pooled effect size mean difference = -17.87 (95% confidence interval: -20.07 to -15.67, P < 0.00001), suggesting that Chinese herbal enema significantly improves postoperative gastrointestinal function. Heterogeneity test I² = 55% (P = 0.05), with moderate heterogeneity present. Square sizes represent study weights, and the diamond represents the pooled effect size and its confidence interval. CI: Confidence interval.

Bowel sound recovery: Pooled analysis results indicated that the overall effect size of the Chinese herbal enema group was MD = -10.36, with 95%CI of (-11.35 to -9.37), Z-value of 24.01 (P < 0.00001), with extremely significant statistical significance. However, heterogeneity testing showed χ² = 13.13 (df = 5, P = 0.02), I² statistic = 62%, suggesting considerable heterogeneity among studies. Despite the presence of heterogeneity, all studies were consistent in direction, supporting that Chinese herbal enema can effectively improve postoperative GI function in gastric cancer patients, providing important evidence-based medicine evidence for clinical application (Figure 4).

Figure 4 Meta-analysis of the effect of Chinese herbal enema on bowel sound recovery time in postoperative gastric cancer patients. Including 6 studies, analyzed using a random-effects model. Pooled effect size mean difference = -10.36 (95% confidence interval: -11.35 to -9.37, P < 0.00001), showing that Chinese herbal enema significantly improves postoperative gastrointestinal function. Heterogeneity test I² = 62% (P = 0.02), suggesting considerable heterogeneity among studies. Squares represent individual study effect sizes, square sizes reflect study weights, and the diamond represents the pooled effect size. CI: Confidence interval.

Intestinal flora improvement rate: This meta-analysis included 6 randomized controlled studies, using a random-effects model to evaluate the effect of Chinese herbal enema on intestinal flora improvement in postoperative gastric cancer patients. The forest plot shows that all studies’ effect sizes were located to the right of the line of no effect, indicating that the experimental group was significantly superior to the control group on this indicator. Effect sizes varied among studies, with Zhang et al[40] having the largest effect size, while Kawasaki et al[35] had the smallest, but all study results were consistent in direction, suggesting positive therapeutic effects of Chinese herbal enema.

Pooled analysis results showed an overall MD = 5.16, with 95%CI of (4.60-5.73), Z-value of 18.03 (P < 0.00001), reaching extremely significant statistical significance, fully demonstrating that Chinese herbal enema can significantly improve intestinal flora status. Heterogeneity test results showed χ² = 31.21 (df = 5, P < 0.00001), I² statistic = 84%, suggesting considerable heterogeneity among studies. Despite the presence of statistical heterogeneity, the direction of effects in all studies remained consistent, indicating that Chinese herbal enema has stable and reliable efficacy in improving intestinal flora in postoperative gastric cancer patients (Figure 5).

Figure 5 Meta-analysis of the effect of Chinese herbal enema on intestinal flora improvement in postoperative gastric cancer patients. Including 6 studies, analyzed using a random-effects model. Pooled effect size mean difference = 5.16 (95% confidence interval: 4.60-5.73, P < 0.00001), suggesting that Chinese herbal enema significantly improves intestinal flora status. Heterogeneity test I² = 84% (P < 0.00001), with considerable heterogeneity present. Squares represent individual study effect sizes and weights, and the diamond represents the pooled effect size. CI: Confidence interval.

Complications: This meta-analysis included 6 studies, using a fixed-effects model to evaluate the effect of Chinese herbal enema on postoperative complications in gastric cancer patients. The forest plot shows that 164 events occurred in the experimental group (total 762 cases) and 163 events occurred in the control group (total 716 cases). Effect sizes of all studies were distributed around the line of no effect (OR = 1), and 95%CIs of all studies crossed the line of no effect, suggesting no statistically significant difference between groups. Among them, point estimates of some studies were slightly greater than 1, while point estimates of other studies were slightly less than 1, indicating no consistent directional trend.

Pooled analysis results showed an overall OR = 0.96, with 95%CI of (0.74-1.24), including the null value of 1, Z-value of 0.30 (P = 0.76), not reaching statistical significance. Heterogeneity testing showed χ² = 0.28 (df = 5, P = 1.00), I² statistic = 0%, indicating excellent homogeneity among studies. This result indicates that compared with conventional treatment, Chinese herbal enema showed no significant difference in postoperative complication rates, demonstrating the safety profile of the intervention (Figure 6).

Figure 6 Meta-analysis of postoperative complication rates in both groups. Including 6 studies, analyzed using a fixed-effects model. Pooled odds ratio = 0.96 (95% confidence interval: 0.74-1.24, P = 0.76), suggesting no statistically significant difference between groups. Heterogeneity test I² = 0% (P = 1.00), with excellent homogeneity among studies. Squares represent individual study effect sizes, and the diamond represents the pooled effect size. CI: Confidence interval.

Bias analysis of the effect of Chinese herbal enema on postoperative GI function in gastric cancer patients: This funnel plot is used to assess whether publication bias exists in studies included in the meta-analysis of postoperative complications. The vertical axis represents standard error SE(log[OR]), the horizontal axis represents OR, the central vertical dashed line represents the pooled effect size, and symmetric oblique dashed lines on both sides form the funnel boundary. The plot includes 6 study points (circles), representing each study included in the analysis. From the distribution, study points are mainly concentrated in the top and middle areas of the funnel plot, suggesting that included studies have relatively large sample sizes and high precision.

Study points are basically symmetrically distributed on both sides of the central line, with most located within the funnel area, showing no obvious asymmetric distribution pattern. This symmetric distribution suggests that this meta-analysis does not have obvious publication bias, and small-sample negative-result studies were not systematically omitted. The absence of missing study points at the bottom of the funnel plot or obvious bias to one side further supports the reliability of this meta-analysis results. Overall, this funnel plot shows that included studies have good representativeness, and analysis conclusions are unlikely to be significantly affected by publication bias (Figure 7).

Figure 7 Funnel plot for bias assessment of postoperative complications in the meta-analysis. The funnel plot is used to assess publication bias for the complication outcome. The vertical axis is standard error SE(log[odds ratio]), and the horizontal axis is odds ratio. The scatter distribution of 6 studies is basically symmetric, concentrated at the top and middle of the funnel, with no obvious asymmetry, suggesting no significant publication bias. MD: Mean difference.

DISCUSSION

The clinical meaningfulness of the observed 10-17 hours acceleration in GI recovery warrants further discussion. A 10-17 hours reduction in GI recovery time translates to approximately half a day to almost a full day of earlier return of bowel function. This acceleration has several important clinical implications: First, it enables earlier initiation of oral feeding, which is a key component of ERAS protocols and is associated with reduced postoperative complications and shorter hospital stay; second, earlier bowel function recovery reduces patient discomfort from abdominal distension, nausea, and vomiting, thereby improving patient-reported quality of life during the immediate postoperative period; third, delayed GI function recovery has been shown to be associated with prolonged hospital stay, and therefore accelerating recovery may contribute to reduced healthcare costs and improved resource utilization.

Postoperative GI dysfunction in gastric cancer is a complex pathophysiological process, and its mechanism involves multiple aspects. First, surgical trauma is one of the main factors leading to GI dysfunction. Radical gastrectomy requires removal of part or all of the gastric tissue and reconstruction of the digestive tract. During surgery, vagus nerve damage is inevitable, particularly the transection of celiac and hepatic branches of the vagus nerve, which impairs GI neural regulation and leads to weakened GI motility[41,42]. Studies show that after vagal transection, the GI tract loses normal nerve innervation, acetylcholine release decreases, GI smooth muscle contraction function declines, gastric emptying is delayed, and intestinal peristalsis slows down[43,44].

Second, mechanical stimulation such as intestinal exposure, traction, and compression during surgery causes intestinal wall edema and congestion, directly damaging intestinal smooth muscle and enteric nerve plexus, leading to weakened intestinal peristalsis. Additionally, prolonged surgical time, increased blood loss, and hypothermia can aggravate intestinal damage and affect postoperative recovery. Third, anesthetic drugs, particularly opioid analgesics, have obvious inhibitory effects on the GI tract[45]. Opioid drugs activate intestinal μ-opioid receptors, inhibit GI smooth muscle contraction, reduce digestive secretion, delay gastric emptying and intestinal transit, leading to postoperative ileus[46,47].

Fourth, neuroendocrine disorders caused by postoperative stress response are also important factors. Surgical trauma activates the hypothalamic-pituitary-adrenal axis and sympathetic nervous system, leading to increased release of stress hormones (such as cortisol and catecholamines), inhibiting secretion of GI motility hormones (such as motilin and gastrin), while promoting release of inhibitory hormones (such as vasoactive intestinal peptide and nitric oxide), further aggravating GI motility disorders[48].

Fifth, postoperative inflammatory response plays a key role in the occurrence of GI dysfunction[49,50]. Surgical trauma triggers intestinal inflammatory response, leukocyte infiltration, and massive release of pro-inflammatory cytokines (such as interleukin-1β, interleukin-6, tumor necrosis factor-α)[51,52]. These inflammatory mediators not only directly inhibit intestinal smooth muscle contraction but can also activate intestinal muscle layer macrophages to produce inhibitory neurotransmitters such as nitric oxide, leading to ileus[53,54].

Sixth, intestinal flora imbalance is an important pathological basis for postoperative GI dysfunction[55,56]. Under normal circumstances, intestinal flora maintains dynamic balance, participating in nutrient metabolism, immune regulation, and maintenance of intestinal barrier function. Gastric cancer patients often have intestinal flora imbalance before surgery due to the disease itself, malnutrition, and antibiotic use[57]. Postoperative fasting, GI decompression, and application of broad-spectrum antibiotics further disrupt intestinal microecological balance, with beneficial bacteria (such as Bifidobacterium and Lactobacillus) decreasing and pathogenic bacteria (such as Escherichia coli, Enterococcus, and Pseudomonas) increasing[58,59]. Intestinal flora imbalance leads to impaired intestinal barrier function, bacterial translocation, and endotoxin release into blood, triggering systemic inflammatory response syndrome and further aggravating GI dysfunction.

In summary, postoperative GI dysfunction in gastric cancer is a complex process involving multiple factors, multiple links, and mutual influences. Therefore, promoting postoperative GI function recovery requires multi-pathway, comprehensive treatment strategies that both protect and restore GI nerve function, inhibit inflammatory response, and maintain intestinal flora balance, providing a theoretical basis for Chinese herbal enema and other integrated Chinese and Western medicine treatments.

Chinese herbal enema, as one of the TCM external treatment methods, has unique advantages and multi-pathway mechanisms of action in promoting postoperative GI function recovery in gastric cancer. First, direct stimulation of intestinal peristalsis is one of the main effects of Chinese herbal enema. Chinese herbal decoction administered rectally allows the medicine to act directly on intestinal mucosa and intestinal wall nerve plexus, stimulating intestinal wall receptors, exciting intestinal smooth muscle, and enhancing intestinal contraction force and peristalsis frequency. Studies show that Chinese herbal enema can activate intestinal interstitial cells of Cajal, which are GI pacemaker cells responsible for generating slow wave potentials and regulating rhythmic contraction of GI smooth muscle[60-62].

Second, the qi-moving, stagnation-resolving, and purgative effects of Chinese herbs can promote discharge of intestinal contents and relieve abdominal distension. The Chinese herbal enema formulas included in this study mainly use rhubarb, mirabilite, immature bitter orange, and magnolia bark as main drugs. Rhubarb is the most commonly used purgative drug, with main active ingredients including emodin, chrysophanol, and aloe-emodin, all anthraquinone compounds[63]. Modern pharmacological research confirms that emodin can stimulate intestinal peristalsis, increase intestinal secretion, soften feces, and promote defecation[64,65]. Mirabilite (magnesium sulfate) has hypertonic effects, forming a hypertonic environment in the intestinal lumen, absorbing water, softening feces, stimulating intestinal walls, and promoting defecation. Immature bitter orange and magnolia bark contain volatile oil components that can promote GI smooth muscle contraction and enhance GI motility.

Third, improving intestinal microcirculation is one of the important mechanisms of Chinese herbal enema. Postoperative intestinal tissue ischemia and hypoxia, edema, and microcirculation disorders are important factors leading to delayed GI function recovery. Blood-activating and stasis-resolving drugs in Chinese herbal enema can improve intestinal microcirculation, increase intestinal wall blood flow, and promote tissue repair[66]. Studies have found that rhubarb can dilate intestinal microvessels, improve microcirculation, and reduce intestinal wall edema and inflammatory response[67,68]. Additionally, Chinese herbs can eliminate oxygen free radicals, reduce ischemia-reperfusion injury, and protect intestinal mucosal barrier.

Fourth, regulating intestinal flora balance is a unique advantage of Chinese herbal enema[69,70]. This study’s results show that Chinese herbal enema can significantly improve intestinal flora improvement rate. Chinese herbs regulate intestinal flora through multiple pathways: (1) Inhibiting harmful bacterial growth. Chinese herbs such as rhubarb, coptis, and scutellaria have broad-spectrum antibacterial effects and can inhibit growth of pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa; (2) Promoting beneficial bacterial proliferation. Chinese herbs can provide nutrients for probiotics and promote growth of beneficial bacteria such as Bifidobacterium and Lactobacillus; (3) Improving intestinal pH and redox potential to provide suitable living environment for anaerobic flora; and (4) Through immunoregulatory effects, enhancing intestinal mucosal immune function and preventing pathogenic bacterial invasion.

Limitations of this study

This study has the following limitations: First, the number of included studies is small and sample sizes are limited, including only 6 RCTs with a total of 843 patients, which may affect the stability and generalizability of results. Second, some outcome indicators have moderate to high heterogeneity (such as bowel sound recovery time I² = 62%, intestinal flora improvement rate I² = 66%), suggesting possible differences in Chinese herbal formulas, administration regimens, and treatment duration among studies, but subgroup analysis could not be performed to explore sources of heterogeneity due to insufficient information in original literature. Additionally, methodological quality assessment of included studies showed unclear descriptions of allocation concealment and blinding implementation in some studies, with possible risks of selection bias and performance bias. Finally, lack of long-term follow-up data prevents evaluation of the effect of Chinese herbal enema on patients’ long-term prognosis and quality of life.

The moderate to high heterogeneity observed in some outcomes (I² = 48%-66%) has potential clinical implications that deserve consideration. The sources of heterogeneity may include: Variations in Chinese herbal formulations used across different studies, as the specific herbs, dosages, and preparation methods may differ; differences in enema administration protocols, including timing of administration, frequency, retention duration, and volume; variations in patient populations, such as differences in age distribution, tumor stage, surgical approach.

CONCLUSION

This meta-analysis results indicate that Chinese herbal enema can effectively promote postoperative GI function recovery in gastric cancer patients, specifically manifested as significantly shortened time to first flatus, time to first defecation, and bowel sound recovery time, improved intestinal flora improvement rate, while not increasing postoperative complication rates, with good safety. As a simple, economical, and effective treatment method, Chinese herbal enema is worth promoting in postoperative recovery of gastric cancer.

In summary, Chinese herbal enema has positive effects on promoting postoperative GI function recovery in gastric cancer patients, with definite efficacy, good safety, and good clinical application prospects. It is recommended that clinicians, in postoperative rehabilitation treatment for gastric cancer, can reasonably apply Chinese herbal enema therapy based on conventional Western medicine treatment and combined with patients’ specific conditions, to achieve integrated Chinese and Western medicine treatment effects with complementary advantages and maximize patient recovery.