Chewing gums has stimulatory eff ects on bowel function in patients undergoing cesarean section: A randomized controlled trial

Th e aim of study was to investigate the eff ect of postoperative gum chewing on the recovery of bowel function after cesarean section. Total  women delivered by lower uterine segment section cesarean under local anesthesia (spinal). Eligible patients were randomly allocated into two groups: a gum-chewing group (n=) or a control group (n= ). Th e gum-chewing group participants who received one stick of sugarless gum for one hours, three times daily immediately after recovery from anesthesia and the control group had the usual postoperative care until being discharged. All women were followed up regularly until discharge from hospital, and recorded the times to the first bowel sounds of normal intestinal sounds, the time to the first passage of flatus, the time to the fi rst feeling of hunger, and the time to the fi rst defecation. Th e operative data, postoperative tolerance of gum chewing, and postoperative complications were documented. Th ere was no statistically signifi cant diff erence between the two groups in terms of demographic characteristics such as age, body mass index, parity, duration of surgery, number of miscarriages and curettages, time to the fi rst feeding, the amount of serum intake, and type of cesarean section. Th e mean average postoperative interval of the fi rst bowel sounds (. versus . hours, p= .), the fi rst feeling of hunger (. versus . hours, p= .), the fi rst passage of fl atus (. versus . hours, P=.), the fi rst defecation (. versus . hours, P= .) was signifi cantly shorter compared to the control group. ©  Association of Basic Medical Sciences of FBIH. All rights reserved


INTRODUCTION
Cesarean section is the most common surgery among women which is associated with central nervous system (CNS) changes in postoperative, leading to decreased bowel movements and driven problems among women (). Postoperative ileus is defi ned as transient cessation of coordinated bowel motility after surgical intervention (), and is one of the major problems of post-abdominal surgery along with delays hospital discharge, abdominal pain, abdominal distension, inability to start oral feeding and, breastfeeding, and eventually increases the cost of hospital care (). Th e pathogenesis of postoperative ileus is multifactorial, but it is more common in cases of preoperative narcotic and drug interaction and abdominal surgery procedures, especially intraoperative bowel manipulation, and temporarily contributes to stop peristaltic (bowel movement); the related mechanism is probably dysfunction in parasympathetic system activity (inhibitory neurons) (). Historically, professionals of gynecology and obstetrics waited until gut function returns allowing oral or entered feeding, characterized by symptoms such as bowel sounds, fi rst fl atus or stool, and feeling of hunger (). When the fi rst passage fl atus or stool is noted it is not an initial return of bowel function. Studies have demonstrated that early postoperative feeding can be safe prior to the return of fl atus or stool (). However, some investigators reported that early feeding was associated with a high rate of intolerance and such as delayed feeding might even lead to increased cell breakdown, delayed wound healing, elevated risk of infection and the need for more intravenous feeding, and eventually additional costs on healthcare system as well as the family (, ). Chewing gum can bring on a feel faint because it stimulate the stomach, enhances gastric secretion, increases peristaltic bowel movements and finally hastens recovery from ileus (-). It has also been recently considered by researchers as a strategy toward ileus reduction. In some studies, beneficial effect of chewing gum has been approved in the resumption of bowel function (-), but in some others such as Quah et al., () contradictory findings have been achieved for the eff ects of gum chewing on peristaltic movements and digestive system stimulation. It seems that a necessity is felt for more investigation on such a least-expensive physiological method in stimulating the return of bowel function. Th erefore, the aim of the present study was to evaluate the eff ect of chewing gum on the recovery of bowel function after cesarean section in women.

MATERIALS AND METHODS
Th is study was approved by Babol University of Medical Sciences for ethics in medical research. A single blind randomized controlled clinical trial was conducted on  women candidates for cesarean section with local anesthesia (spinal) in gynecology ward of Hospital during June  to March . The nature of the study did not allow blinding after assignment of the intervention postoperatively. Written informed consent was obtained from  enrolled women. All enrolled women were allocated using a computer-generated random sequence from a statistics program. All cesarean section were carried out by a Gynecologic Surgeon (an author) in the morning. A transverse incision on the uterus and a Pfannenstiel incision on the abdomen were performed. Demographic information on all variables women included; patient's age, body mass index, number of pregnancies, miscarriage and uterine curettages. Exclusion criteria were: women with history of drug consumption, especially opioids, water and electrolyte disturbances, pancreatitis or peritonitis, history of abdominal surgery except cesarean section, no willingness to cooperate, intra-and sever postoperative complications, inability to chew gum, withdrawal, diabetes, pre-eclampsia, prolonged rupture of membranes, hypothyroidism, and muscular and neurological disorders. The operative data were recorded, including the presence of severe adhesions, the occurrence of intraoperative complications, estimated blood loss and duration of surgery. Data-collection instruments included the interview form, questionnaires, and subjects' examination. For each of the study participants, a questionnaire, designed based on characteristics and the research objective. The women in the chewing gum group chewed sugar-free gum for at least one hour, three times daily from six hours after surgery (after recovery from anesthesia) until being discharged. Commercially available sugar-free gum (Wrigley Company, Poland) was used in this study. The oral intake of clear fluids and soft foods was initiated on postoperative day. Only after documentation of bowel function, which they was determined with the presence of any two of the following three criteria: () bowel sounds; () fl atus; and () felling of hunger. In order to reduce the eff ects of other variables, the postoperative feeding regime was standardized for the all women. Around  hours following operation, the women were discharged when they had stable vital signs with no febrile morbidity for at least  hours, ability to ambulate and urinate independently, defecation, ability to tolerate solid food and absence of sever other post surgery complications. For post-operative analgesia,  mg rectal sodium suppository diclofenac was routinely given three times daily. All women were followed up regularly until discharge from hospital, and recorded the times to the first bowel sounds of normal intestinal sounds, the time to the first passage of flatus, the time to the fi rst feeling of hunger, and the time to the fi rst defecation. Also, postoperative tolerance of gum chewing and postoperative complications was documented. However, any side eff ects, and unresolved postoperative complication presented by the women during the postoperative period were to be recorded. Before intervention,  enrolled women were excluded due to considered by surgeon to be inappropriate for this study. All analyses were performed with SPSS (version.). The data were analyzed by t test and chi square. A p value of . or less was considered statistically significant.

RESULTS
Th ere was no statistically signifi cant diff erence between the two groups in terms of demographic characteristics such as age, body mass index, parity, duration of surgery, number of miscarriages and curettages, time to the fi rst feeding, the amount of serum intake, and type of cesarean section (Table ).. In gum-chewing group, the first bowel sounds was significantly shorter compared to the control group (p=.). The first defecation was . hours in the gum group and . hours in the control group (p=.). The fi rst passage of fl atus was seen on postoperative hours . in gum chewing group and on hours . in the control group respectively (p=.), and also the first feeling of hunger were felt on postoperative hours . in the gumchewing group and . hours in the control group (p=.). None of the participants felt dissatisfied with chewing gum and none were excluded from the study (Table ).

DISCUSSION
Th e women were well tolerating the gum and no feeling of dissatisfaction, and none were therefore excluded from the study. The study findings has shown reduced time to the fi rst bowel sounds, defecation, passage of fl atus, and feeling of hunger following chewing gum after the cesarean section. In this study, the mean time to the fi rst bowel movement revealed remarkable diff erence between the two groups, which is in accordance with Dehcheshmeh study on the eff ects of chewing gum after elective cesarean section on  primiparous women in Shahrekord in , reporting .±. hours and .± . hours as the mean time to the first bowel movement in the gum and the control group respectively (, , ); the fi nding is also in consistent with Schuster study on the impact of gum chewing after sigmoid-colostomy surgery on  patients in , in which the mean time to the fi rst bowel movement was .±. hours and .±. hours in the gum and the control group (). Nonetheless, in Akhlaghi survey on the eff ect of chewing gum on the resumption of bowel function after cesarean section on  patients in Mashhad in , the two groups were diff erent in terms of the feeling of bowel movement, but not statistically significant, as the mean diff erence was .±. hours and .±. hours in gum-chewing and the control group respectively. Th is study is not in agreement with the present research, and the reason behind such a contradiction may be due to sampling and/or surgical conditions (). Other variable examined in terms of bowel function was the feeling of hunger which was  hours earlier in the chewing gum group than the other and was statistically signifi cant; this fi nding is in consensus with Satij results following the caesarean section in  (); however, in Schuster study, the two groups were diff erent on the feeling of hunger, but not statistically signifi cant, as the mean time to the feeling of hunger was .±. hours and .±. hours in the chewing gum and the control group respectively (); such a discrepancy could be owing to the small sample size in Schuster study. In the present research, the mean time to the fi rst defecation displayed signifi cant difference between the two groups as it happened  hours earlier in the gum than the control group, similar to the results obtained by Maeboud, Ghafouri, Hirayama, Hocevar and Abdollahi (, , , , ). So as, in Maeboud study on  patients after elective caesarean section in Egypt in , the mean time of defecation was .±. hours and .±. hours earlier in gum-chewing and the control group, and in Hirayamai and Ghafouri studies, respectively on  patients with upper gastrointestinal tract surgery in  in Tehran and colorectal surgery on  patients in  in Japan, defecation time was  hours earlier in gum-chewing than the control in both studies, which was statistically meaningful. In Abdollah investigation on  patients following appendectomy surgery in Gorgan in , the time to the fi rst defecation was  hours earlier in the gum than the control group and was statistically signifi cant. However, in a research on  patients after left colon cancer surgery in England in , no statistical diff erence was observed in the time to the fi rst defecation between the gum (.±. hours) and the control (.±. hours) group (), about which small sample size and type of surgery may be the reasons for such a diff erence. Th e mean passage of fl atus was the other variable evaluated on intestinal function, happening, on average,  hours earlier in the gum than the control group; this fi nding is in consistence with Kouba investigation on  patients undergoing bladder radical surgery in  in America, in which the time to the fi rst passage of fl atus was respectively . and . days in the gum and the control group, showing acceleration of gas passage following chewing gum after bladder surgery (). In Ngowe study in  on  patients with open appendectomy, the mean time of gas passage was . and . days in the gum and the control group (). In Choi survey on  patients in , the mean time to the passage of fl atus was  h and  hours in gum-chewing and the control group and statistically signifi cant (); whilst, Quah reported no remarkable diff erence between the two groups in terms of gas passage. There is not yet an independent investigation on the exact chewing gum mechanism of action. However, some theories discuss gum as a form of sham feeding that chewing resulting in propulsive gastrointestinal activity through cephalic-vagal stimulation (, ). It is suggested that cephalic-vagal mechanism being less eff ective in women undergoing cesarean section under local anesthesia (). In addition, sugar free chewing gum that contains the artifi cial sweetener sorbitol and other hexitols might be having side effects such as bloating, gas, and abdominal cramps. However there is no reported about the possible eff ects of the ingredients of these gums (). Moreover, in this study was found sugar free chewing gum safe and tolerated by all patients. Th erefore, it is suggested that the content of maxitols in 'sugar-free' chewing gums may play a role in the amelioration of ileus after surgery and future studies are needed to investigate probable mechanisms involved in the observed phenomena.

CONCLUSION
The results of the present study indicate that chewing is acceptable and inexpensive physiologic method for decreasing the time to the passage of flatus, bowel movements, and feeling of hunger in patients undergoing cesarean section. It can be added to post-caesarean care without any concern on early post-operation feeding as a low-cost, safe and tolerable treatment in early intestinal stimulation to reduce ileus associated complications.

ACKNOWLEDGMENTS
The present study is a research project, Contract No. and IRCT registration No. N, approved by Babol University of Medical Sciences; hereby, the authors would like to appreciate the university authorities, and Ms. Shokat Asghari, and also respected personnel of the surgical ward of Rouhani Hospital of Babol for their sincere cooperation.

DECLARATION OF INTEREST
The authors declare that there is no conflicting interest.