Abstract
BACKGROUND:
Flatulence is one of the gastrointestinal complaints after a cesarean section (C-section). A host of treatments have been used to reduce this symptom in hospitals, and most of them are based on chemical drugs. It is considered that herbal drugs may have fewer side effects than chemical drugs, and it seems that fennel can reduce flatulence through stimulation of bowel movements. This study compared the efficacy of fennel and dimethicone capsules on the flatulence rate in post-cesarean birth women.
MATERIALS AND METHODS:
This study was a parallel double-blind randomized controlled trial, conducted in a teaching hospital. Eligible women who underwent a C-section and had the sensation of flatulence were randomly block allocated to the fennel and dimethicone groups (1:1). Each group received drugs every 6 hours for four doses after restarting oral feeding. Flatulence rate was the main variable measured before and one hour after taking each dose by the visual analog scale (VAS). Data were analyzed by statistical tests including repeated-measures analysis of covariance (ANCOVA) based on the intention-to-treat method in Statistical Package for the Social Sciences (SPSS) version 16.0.
RESULTS:
The dimethicone group showed a significant reduction in flatulence (F (7,245) =198.5, P < 0.001, η2p = 0.850). The same trend was also obtained for the fennel group (F (7,266) =215.0, P < 0.001, η2p = 0.849). However, there was no difference between groups on the flatulence level after adjusting for the baseline level of flatulence (F (1,72) =0.27, P = 0.607, η2p = 0.004). The same result was also obtained one hour after taking capsule 4 (F (1,72) =0.63, P = 0.430, η2p = 0.009).
CONCLUSION:
Both fennel and dimethicone capsules can reduce flatulence rate after C-section, although there was no significant difference among them.
Keywords: Cesarean section, dimethicone, fennel, flatulence, Foeniculum, herbal medicine, ileus
Introduction
Cesarean is the most common surgical procedure in obstetrics and gynecology departments worldwide.[1] Decreased or delayed return of bowel motility is a complaint after a cesarean section (C-section).[2] Factors such as opioids and intraoperative intestinal manipulation can induce postoperative ileus (POI), which is common after gynecologic surgery and C-section associated with a wide range of symptoms such as nausea, vomiting, pain, abdominal distension, and/or flatulence.[3,4,5]
Flatulence is defined as the subjective feeling of increased abdominal pressure or being distended, which may or may not be obvious objective distension.[6] The complication prevalence is 16–31% in the general population and 20–40% in mothers after C-section.[7,8] Flatulence, abdominal distension, and/or indigestion after surgery can induce abdominal pain and possibly respiratory problems, including dyspnea, chest pain, and rupture of the incisional sutures, and this complication can prolong the hospital stay, decrease maternal satisfaction, and delay mother and baby bonding.[2,9,10]
To reduce or prevent gastrointestinal symptoms after surgery, various herbal medicines such as dill, ginger, and Carum carvi and some chemical drugs such as metoclopramide and simethicone were used in different clinical trials.[2,4,8,9,11] Dimethicone and simethicone are the chemical drugs used in many countries to reduce the symptoms caused by excess intestinal gases and improve the passage of flatus after surgery and preparation protocol before endoscopic procedures to get a clear view due to their anti-foaming effect.[11,12,13,14] One study showed that preoperative oral simethicone may reduce POI symptoms and pain after gynecological laparoscopy.[15] In another clinical trial, simethicone did not significantly reduce the bloating experienced after colorectal surgery. However, the side effects of these drugs have been reported in 2–5% of patients.[11] There is a risk that chemical medications may be transmitted to infants through breast milk.[9] Based on the current evidence, it is considered that herbal drugs may have fewer adverse side effects than chemical drugs due to their antioxidant properties; however, more proof is needed. Nowadays, the world is moving to merge complementary medicine with modern medicine. Traditional medicine is one of the most important branches of complementary medicine. Also, in Persian medicine, some herbal medicines are advised to relieve flatulence.[16,17]
Fennel is one of these herbs, called “Razianeh” in Persian. This plant belongs to the Umbelliferae (Apiaceae) family and is known by more than 100 names. Its scientific name is Foeniculum vulgare. Fennel has the effects of analgesic, anti-allergic, anti-inflammatory, antispasmodic, antioxidant, antibacterial, anti-stress, gastro-protective, and galactogenic activity.[17,18,19,20] Moreover, fennel has been used to manage dysmenorrhea, premenstrual syndrome, polycystic ovary syndrome, amenorrhea, and postpartum pain in various forms. It has not reported the adverse effects associated with fennel in the postpartum period.[21,22,23,24,25,26,27]
The main ingredient in fennel is trans-anethole. Anethole is chemically similar to dopamine, and it has a relaxant effect on intestinal smooth muscles.[19,28] Fennel has galactogenic properties, which means it helps increase milk secretion.[18] Besides, fennel can increase bowel movements, and its antispasmodic effect is used as a laxative in the treatment of digestive disorders such as constipation.[18,29] Chen et al.[30] showed in their study that the use of heated fennel on the abdomen could improve gastrointestinal motility function after complex abdominal surgeries but indicated no beneficial effect on the levels of inflammatory markers and abdominal pain. One Iranian study revealed that using a soft fennel capsule could reduce afterpain without any adverse effects in the postpartum period.[22] In another study, it was found that the use of fennel tea can accelerate the return of gastrointestinal function after gynecological malignancy surgery by increasing bowel movements.[31] Moreover, fennel essential oil can improve the symptoms and quality of life in patients with irritable bowel syndrome (IBS).[28] It seems that fennel seed extract may be used as adjunctive therapy in inflammatory bowel disease (IBD) due to the anti-inflammatory effect.[32]
These studies imply that fennel may improve gastrointestinal function by stimulating intestinal peristalsis. However, the effectiveness of fennel in postoperative is still uncertain. To the best of our knowledge, no study has been conducted on the efficacy of fennel on postpartum flatulence or comparing the effect of herbal and chemical drugs together on gastrointestinal disorders after C-section. Therefore, this study aimed to compare the efficacy of fennel soft capsule and dimethicone soft capsule on the flatulence rate in women after cesarean birth. The research hypothesis was that flatulence levels in post-cesarean mothers differed between the fennel and dimethicone groups before and after the intervention.
Materials and Methods
Study design and setting
This study was a double-blind, parallel-group, randomized controlled superiority trial that compared the effect of fennel and dimethicone capsules on the rate of flatulence in mothers who had given birth via C-section at Alzahra Governmental Teaching Hospital, Rasht, Guilan, in 2021.
Study participants and sample size
Eligible women who had given birth by C-section for any reason were recruited into the trial. Participants were randomized into the fennel and dimethicone groups. The sample size was determined using G*Power version 3.1.9.2[33] with an effect size of 0.7, a power of 0.8, and an alpha value of 0.05, and 34 mothers would be necessary for each group. Assuming a potential dropout rate of 15%, 40 mothers were needed in each group. The study’s participants were included based on the inclusion and exclusion criteria given as follows.
Inclusion criteria included the willingness to participate in the study and sign a written informed consent form; at least the ability to read and write; full-term delivery (gestational age of 37–42 weeks); feeling of flatulence; no contraindication of fennel capsules such as a history of asthma, seizures, liver disease, cancer, epilepsy, and allergic reaction to celery or fennel according to the mother’s statement and file information. Exclusion criteria included the occurrence of any complication in terms of using the capsules, possible uterine atony and subsequent bleeding, and unwillingness to continue cooperation in the study.
Randomization
Participants were randomly assigned to both groups at a ratio of 1:1. A blocked randomization method with block sizes of 4 and 6 was performed using an online randomization service, Sealed Envelope Ltd. 2019 (available at https://www.sealedenvelope.com/).
Group A as the study group received fennel capsules, whereas group B as the control group received dimethicone capsules. Dimethicone is the common anti-flatulence drug in the hospital postpartum unit. Fennel and dimethicone capsules were purchased by the first author. The investigators and participants were blinded. For this purpose, the shape of the packages containing the capsules (fennel and dimethicone) were in the same color, size, and opaque. These packages were tagged with a specific code based on the randomized list to protect against treatment blinding. Each package contained 4, 30 milligrams (mg) of fennel soft capsules called fennelin and supermint (that was standardized based on 21–27 mg of anethole in each one, made by Barij Essence Pharmaceutical Company, Kashan, Iran) or 4, 125 mg of dimethicone soft capsules (consisting of 125 mg dimethicone activated that was made by Zahravi Pharmaceutical Company, Tabriz, Iran).
Data collection tool
The primary outcome was the rate of flatulence changes after C-section using the visual analog scale (VAS). VAS is a subjective tool often used in epidemiologic and clinical research to measure the rate of various symptoms, especially pain. Its validity and reliability have been established previously. The scale used in this study is the simplest horizontal shape, which is 100 millimeters in length.[34,35] In other words, the number 0 indicates “no flatulence at all” and the number 100 indicates “worst rate of flatulence.”
Study intervention
The intervention was initiated when oral feeding with a clear liquid diet restarted about 18 hours after the surgery. Eligible women who had positive responses to questions about the existence of flatulence before beginning any intervention, their demographic and fertility information including age, body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters), family’s income, education, occupation, gestational age, gravidity, parity, duration of C-section, and type of anesthesia have been recorded by the first investigator based on the women’s self-report and medical files. Then, participants in both groups received the pack of capsules and were recommended to take each capsule every 6 hours (four doses) with a glass of full water. Before taking each dose and one hour after that, the participants were asked to mark their flatulence rate on the VAS, total of eight times. According to the common postoperative protocol in the hospital, all participants received an intravenous antibiotic every 6 hours during the first day after the C-section and a pain-relief suppository every 8 hours if necessary.
Statistical analysis
The continuous variables were expressed as mean (standard deviation (SD)) and categorical variables as frequency (percentage). Using the Shapiro–Wilk test, variables were checked for normal distribution. An analysis of covariance (ANCOVA) was used to compare the groups after controlling for pre-intervention scores. Furthermore, effect sizes were reported in partial eta-squared (η2p) for ANCOVA; η2P values of 0.01–0.06, 0.06–0.14, and >0.14 were considered low, moderate, and high effect sizes, respectively. Besides, repeated-measures analysis of variance (ANOVA) was used to examine trend over time for the outcome variables. Data analysis was performed using Statistical Package for the Social Sciences (SPSS) for Windows, version 16.0 (SPSS Inc., Chicago, IL, USA), and error bar graphs were depicted using GraphPad Prism, version 8.0.1 (GraphPad Prism Software Inc., San Diego, CA, USA). A P < 0.05 was considered statistically significant.
Ethical consideration
This study was approved by the Ethics Committee of Guilan University of Medical Sciences, Rasht, Iran, on June 30, 2021 (Ethics Code: IR.GUMS.REC.1400.152). This trial was also registered on 2021-07-20 at www.irct.ir (Trial Registration Number: IRCT20160630028717N2, available at https://en.irct.ir/trial/57069). All mothers were fully informed about the aim of the study, the confidentiality of information, and the voluntary nature of their participation and signed a written informed consent form. All participants were also reassured that they could withdraw from the study at any time if they were unwilling to cooperate.
Results
A total of 130 mothers were screened, and 80 patients underwent randomization in July 2021 and the last was on August 29, 2021. Of these, follow-up data were available for 75 patients (100.0%) to be included in the intention-to-treat analysis [Figure 1].
Figure 1.
Randomized controlled trial CONSORT flow diagram of study participants
Table 1 presents the demographic and clinical characteristics of the participants. The mean age of the mothers was 30.9 (SD = 6.2) years, and the mean BMI was 33.1 (SD = 5.5) kg/m2. Of the participants, 18.7% had a university education, 8.0% were employed, and 20.0% were residents of rural area. Demographics and clinical characteristics were well balanced between the dimethicone and fennel groups. Based on the result of the independent t-test, there was no significant difference in terms of age, height, weight, BMI, gestational age, and duration of C-section between the dimethicone and fennel groups (P > 0.05). The result of the Chi-square test in terms of gravidity, parity, education level, place of residence, and family’s income in the dimethicone and fennel groups showed that there was no significant difference between the groups (P > 0.05). The result of Fisher’s exact test indicated that there was no significant difference in terms of occupation (P = 0.419) and type of anesthesia (P = 0.605) between the two groups.
Table 1.
Baseline characteristics of study participants
| Total (n=75) | Group |
||
|---|---|---|---|
| Dimethicone (n=36) | Fennel (n=39) | ||
| Age (years) | 30.9 (6.2) | 30.9 (6.1) | 30.9 (6.4) |
| Height (cm) | 162.1 (5.7) | 162.3 (5.7) | 162.0 (5.9) |
| Weight (kg) | 87.2 (16.7) | 88.4 (14.2) | 86.2 (18.8) |
| BMI (kg/m2) | 33.1 (5.5) | 33.6 (5.1) | 32.7 (5.9) |
| Education | |||
| Under diploma | 31 (41.3%) | 13 (36.1%) | 18 (46.2%) |
| Diploma | 30 (40.0%) | 15 (41.7%) | 15 (38.5%) |
| University | 14 (18.7%) | 8 (22.2%) | 6 (15.4%) |
| Occupation | |||
| Housewife | 69 (92.0%) | 32 (88.9%) | 37 (94.9%) |
| Employed | 6 (8.0%) | 4 (11.1%) | 2 (5.1%) |
| Place of residence | |||
| Urban | 60 (80.0%) | 31 (86.1%) | 29 (74.4%) |
| Rural | 15 (20.0%) | 5 (13.9%) | 10 (25.6%) |
| Family’s income | |||
| Less than sufficient | 24 (32.0%) | 9 (25.0%) | 15 (38.5%) |
| Sufficient | 40 (53.3%) | 21 (58.3%) | 19 (48.7%) |
| More than sufficient | 11 (14.7%) | 6 (16.7%) | 5 (12.8%) |
| Gestational age (weeks) | 38.1 (1.0) | 38.2 (1.1) | 37.9 (1.0) |
| Gravidity | |||
| G1 | 23 (30.7%) | 12 (33.3%) | 11 (28.2%) |
| G2 | 22 (29.3%) | 10 (27.8%) | 12 (30.8%) |
| ≥G3 | 30 (40.0%) | 14 (38.9%) | 16 (41.0%) |
| Parity | |||
| P1 | 25 (33.3%) | 14 (38.9%) | 11 (28.2%) |
| P2 | 37 (49.3%) | 18 (50.0%) | 19 (48.7%) |
| ≥P3 | 13 (17.3%) | 4 (11.1%) | 9 (23.1%) |
| Duration of C-section (min) | 50.6 (7.6) | 50.3 (8.2) | 50.9 (7.1) |
| Type of anesthesia | |||
| SA | 72 (96.0%) | 34 (94.4%) | 38 (97.4%) |
| GA | 3 (4.0%) | 2 (5.6%) | 1 (2.6%) |
Data are mean (standard deviation) or n (%). BMI: Body mass index. SA: Spinal anesthesia. GA: General anesthesia
Flatulence level
The overall trend of flatulence levels across the study period is indicated in Figure 2. According to the repeated-measures ANOVA, throughout the intervention, the mothers in the dimethicone group showed a significant decline in flatulence levels (F (7,245) =198.5, P < 0.001, η2p = 0.850). The same trend was also obtained for the fennel group (F (7,266) =215.0, P < 0.001, η2p = 0.849).
Figure 2.
Overall trends of flatulence during the intervention in the dimethicone and fennel groups. Data are mean and 95% confidence interval (95% CI). Note. Flatulence was measured using a VAS ranging from 0 (no flatulence) to 100 (maximum flatulence). CAP: Capsule
Table 2 shows the results of ANCOVA examining the group effect on post-intervention flatulence scores. Accordingly, one hour after taking capsule 1, there was no difference in the flatulence levels between the dimethicone and fennel groups after adjusting for the baseline level of flatulence (F (1,72) =0.27, P = 0.607, η2p = 0.004). The same results were also obtained between both groups before taking capsule 2 and one hour after that, before taking capsule 3 and one hour after that, and before taking capsule 4. Moreover, one hour after taking capsule 4, no statistically significant difference was observed in the adjusted mean difference scores of flatulence levels between both groups (F (1,72) =0.63, P = 0.430, η2p = 0.009).
Table 2.
Results of ANCOVA examining group effect on post-intervention scores of flatulence level
| Dimethicone (n=36) | Fennel (n=39) | Adjusted mean difference (95% CI)a | F (1,72) | P | η2p | |
|---|---|---|---|---|---|---|
| Before CAP 1 | 67.9 (13.5) | 69.3 (13.3) | - | - | - | - |
| After CAP 1 | 56.2 (11.3) | 56.3 (11.9) | -0.9 (-4.2 to 2.5) | 0.27 | 0.607 | 0.004 |
| Before CAP 2 | 54.3 (13.2) | 56.6 (12.5) | 1.2 (-2.2 to 4.6) | 0.52 | 0.474 | 0.007 |
| After CAP 2 | 45.0 (12.8) | 46.8 (12.0) | 1.0 (-3.1 to 5.0) | 0.22 | 0.638 | 0.003 |
| Before CAP 3 | 40.6 (11.7) | 44.7 (13.4) | 3.3 (-1.1 to 7.6) | 2.22 | 0.141 | 0.030 |
| After CAP 3 | 32.7 (10.9) | 35.2 (13.9) | 1.8 (-3.2 to 6.8) | 0.52 | 0.475 | 0.007 |
| Before CAP 4 | 27.7 (10.5) | 31.7 (13.4) | 3.6 (-1.5 to 8.6) | 1.97 | 0.164 | 0.027 |
| After CAP 4 | 19.7 (9.0) | 21.9 (12.1) | 1.9 (-2.9 to 6.8) | 0.63 | 0.430 | 0.009 |
Data are mean (standard deviation), unless otherwise specified. CI: Confidence interval; CAP: Capsule. aAdjusted for the pre-intervention level of bloating
Discussion
This double-blind randomized controlled trial compared the effect of fennel and dimethicone capsules on flatulence rate after C-section. The main finding of this study showed that both fennel and dimethicone capsules had a trend toward reducing the rate of flatulence after C-section, but there is no significant difference between the fennel and dimethicone groups on flatulence rate. Also, participants reported no side effects such as heavy postpartum bleeding during the intervention period.
To our knowledge, there are no recent studies to compare the effect of fennel and dimethicone capsules on flatulence rate after C-section. However, some trials showed the effect of these drugs on gastrointestinal function. A prospective randomized controlled trial in 381 patients undergoing abdominal surgery who used 500 grams (g) heated fennel as the intervention group and 500 g heated rice as a placebo on the abdomen, six to eight times per day after the operation, showed an earlier time of the first flatus and reduced abdominal distension in the fennel group compared with the control group.[25] In another study, Ma et al.[30] assessed the preventive effect of fennel tea on a total of 159 women undergoing laparotomy for gynecological cancers. Patients drank a cup of fennel tea (5 g dried fennel fruit and 130 milliliters (ml) boiled water) or equal quantity of water as a placebo twice a day from the first morning after surgery until the first flatus occurred. The mean time of flatus and the occurrence of Ileus symptoms were significantly lower in the tea group than in the control group. It seems that fennel through its effective agent called trans-anethole can cause a relaxant effect on intestinal smooth muscles.[19,26] However, some investigators believed that fennel could increase bowel movements and at the same time can reduce the amount of intestinal gas and flatulence.[18]
These studies indicated a beneficial effect of fennel on gastrointestinal function after surgery like our results, but none of them assessed a specific symptom such as flatulence in post-cesarean women. Besides, the robust points of our study were that we measured flatulence level eight times, including before and 1 hour after each dose, and we assessed the trend of flatulence rate in two groups. Moreover, we considered the common anti-flatulence drug (dimethicone) used in the hospital postpartum unit instead of a placebo since we could not debar participants from medication.
Simethicone/dimethicone was a chemical drug, which is used to prevent and manage gastrointestinal disorders, including POI after surgery, and relieve the symptoms of intestinal gas. Another single-blind controlled trial compared the effect of dimethicone and supermint on flatulence in 60 patients with IBS. Patients received 40 drops of supermint in 20 ml of water or 40 mg chewable tablet of dimethicone after each meal for 3 weeks. This study showed no significant difference in flatulence between the two groups two weeks after the intervention, but the supermint group experienced less flatulence compared with the dimethicone group four weeks after the intervention.[12] This result was similar to our study in terms of flatulence level reduction in the dimethicone group and there was also no significant difference between the two groups, although the duration of intervention and participants in our study were different.
In another double-blinded, placebo-randomized controlled trial, Springer et al.[11] evaluated the effect of simethicone on the reduction of ileus in 118 patients undergoing colorectal surgery. Patients received 160 mg of simethicone or placebo four times a day, starting the first day until the fifth day post-operation. There was no significant difference in the postoperative pain scores, length of stay, and symptoms, including abdominal distension, bloating, and cramping between the two groups. It seems that colorectal surgery is more complex than C-section in our study and intestinal manipulation is possibly more.
Limitations and suggestions
A limitation of the present study was that the flatulence levels evaluated by mothers were self-reported and mostly subjective in the sense that anyone can feel various Intensities. Another limitation was that the investigators followed abnormal postpartum bleeding as a possible side effect in the short term. Further studies are suggested to evaluate the long-term effects.
Conclusion
This was the first randomized controlled trial comparing the effect of fennel and dimethicone capsules on flatulence rate after C-section. This study shows that both capsules can reduce flatulence rate after C-section. However, there is no significant difference between using fennel and dimethicone capsules on flatulence rate. It is suggested that further studies be performed in a multicenter with a larger sample size to confirm these findings.
Financial support and sponsorship
The authors did not receive support from any organization for the submitted work. This research did not receive any specific grants from funding agencies in the public, commercial, or not-for-profit sectors.
Conflicts of interest
All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or nonfinancial interest in the subject matter or materials discussed in this manuscript.
Acknowledgements
This study was extracted from the MSc. thesis approved by the Ethics Committee of Guilan University of Medical Sciences, Rasht, Iran (Ethics Code: IR.GUMS.REC.1400.152). The authors would like to express their thanks to the Vice Chancellor of Research and Technology of Guilan University of Medical Sciences (GUMS), Rasht, Iran, for scientific, administrative, and technical support of this study and to all mothers who took part in this study.
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