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INTRODUCTION
Fecal incontinence (FI) is a clinically debilitating complication, which is normally caused by an underlying abnormality, operative procedure or a neurological deficiency [1]. The most common surgery that is performed to treat Hirschsprung disease (HD) is the transanal pull-through surgery (TAPTS) [2]. HD is a congenital absence of ganglion cells in the distal intestine. Despite the effectiveness of these procedures in restoring bowel continuity, postoperative FI is a frequent and painful complication that exposes patients to severe physical, emotional, and social disabilities [3].
There is geographical variation in the rate of FI in pediatric populations. Reported rates in high-income Western countries are 0.8%–4.1%, but in the few Asian countries, the incidences are 2%–7.8% [4]. There is limited epidemiological evidence on this topic in Egypt, which implies that postoperative FI is very common in this country after TAPTS of HD; nonetheless, there is a lack of large-scale studies on the topic nationwide [5].
FI has adverse effects on the quality of life (QOL), daily functioning, socialization, and education. Children suffer psychological trauma, humiliation and social isolation, which translate to low self-esteem, depression and anxiety [6].
Treatment of FI involves conservative and rehabilitative modes, such as behavioral training, biofeedback, and pelvic floor muscle training [7]. Electrical stimulation (ES) also seems to have the most potential, as it might help to increase the tone of the anal sphincter (AS), neuromuscular coordination, and voluntary bowel control [8]. The method may be performed through rectal electrodes directly stimulating external and internal sphincters or surface electrodes, which is a less invasive instrument [9]. The training of the AS is one of the essential elements in the rehabilitation process of FI, which is performed to enhance the external AS, improve the voluntary control, and bring functional benefits. There are maximum voluntary contractions (MVCs), rapid contractions, endurance holds and coordinated breathing exercises [10].
Since the AS training and ES may be potentially useful, but the body of comparative literature on the use of surface electrodes versus rectal electrodes placement in pediatric FI after TAPTS in HD is limited, the comparison between the efficacy of these modalities is urgently required. This kind of research would help to develop evidence-based, standardized rehabilitation guidelines, which result in the highest level of continence and QOL. On this basis, the current study aimed at contrasting the impact of rectal and surface electrode ES with and without AS exercise in children with postoperative FI [11,12]. The main aim was to determine the most effective intervention to improve sphincter performance, decrease the instances of incontinence and improve QOL. The results can be used to generate powerful clinical evidence to direct practice in pediatric physiotherapy as well as influence national rehabilitation policies and eventually reduce the psychosocial burden of FI among children with HD.
METHODS
Study design
The study was a prospective randomized controlled trial with a parallel-group design that compared the effectiveness of rectal versus surface electrode ES that was used in combination with AS exercises and biofeedback training in managing FI in children who had undergone TAPTS to treat HD. The researchers adopted a pre-test/post-test design whereby outcome assessment was done at baseline, after an 8-week intervention period, and later at a 12-week follow-up period after the study was over.
Sample size calculation
G*Power (version 3.1.9.7) was used to calculate the sample size with a primary hypothesis of a difference in time x group interaction in a repeated-measures design. A medium effect size (Cohen’s f=0.25; synonymous with d=0.5) was chosen as the design parameters based on the findings of previous clinical trials assessing ES and biofeedback as bowel and pelvic-floor rehabilitation interventions in children [13]. G*Power analysis revealed that 60 participants would be needed to reject the null hypothesis and accept the alternative hypothesis that there is a specified group x time interaction, given that there are two groups and three measurement occasions (baseline, post-treatment, and follow-up) and 2 tails of alpha=0.05 and that there is a sphericity correction (1). To consider the possibility of attrition and maintain power, the sample size was increased by 10% to give the final target of 67 subjects (Group A, n=34; Group B, n=33).
Study setting
The study was implemented along a span of 9 months, between January and September 2025 at the outpatient clinic of the Faculty of Physical Therapy, Cairo University. The recruitment of the participants from Cairo University Hospitals after thorough examination and conclusive diagnosis by qualified and licensed pediatricians and consultants. The Institutional Review Board of the Faculty of Physical Therapy, Badr University in Cairo gave this research ethical approval (approval no.: IRB00014233-2) before the study was conducted. The study was registered as a clinical trial on the Pan African Clinical Trials Registry (PACTR) under the registration number PACTR202510484282271 (website: pactr.samrc.ac.za). The study followed the principles of ethics that were established in the Declaration of Helsinki and its further amendments. Informed consent was signed by parents or legal guardians of all the participating children after giving them a clear description of the study goals, procedures, risks, and pros that would be expected. The participants were assured that their personal information be disclosed and that they had the right to pull out of the study at any given time.
Participants
Sixty-seven children aged 6–14 years, who participated in this study, specified that they had persistent FI after TAPTS to correct HD. The participants were selected among a group of the patients diagnosed with the condition but had already received the specified operation, were in good health, and had given their consent and a recommendation of a pediatric surgeon and pediatrician to take part in the rehabilitation program. Each of the participants showed the ability to obey and understand the simple instructions and the necessary cooperation. The inclusion criteria were that there must be at least six months of FI after the operation. The exclusion criteria included any of the following: patients with neurological conditions that impact on continence, other congenital anomalies that might affect bowel function, severe intellectual disability which might exclude participation, perianal or gastrointestinal infection or dermatologic condition, and absence of informed or parental consent. Thus, the group that included a rectal electrode received AS exercises and biofeedback training (Group A) included 34 participants, whereas the group that received a surface electrode, and the use of AS exercises and biofeedback training (Group B) included 33 participants.
Randomization and allocation
The study (Group A) and control (Group B) groups were assigned participants in a computer-generated randomizing list, to prevent possible bias, opaque sealed envelopes with the randomization results were prepared by a non-involved team member. The opening of each envelope was done only when the intervention was initiated, which prevented any effect of the results by the enrolling clinician. Outcome assessors and data analysts were blinded where possible to the allocation of groups of participants. Assessment data was coded to prevent unintentional revelation of allocation status.
Outcome measures
Primary outcome:
(1) The Bowel Function Score
Bowel Function Score (BFS) is a strictly validated tool that has been used to assess the bowel capability and fecal continence in pediatric and clinical groups. Empirical evidence has supported its content validity, and sensitivity to clinically significant levels of change across time. Moreover, the BFS is highly reliable, which is proven by the fact that there is no significant variation in the results of tests conducted in succession and among different raters in case of following the standard set of instructions. Domains measured on the scale include the rate of soiling, stool features, the effects of the day-to-day activities and the QOL, and the possibility of the management plans. The scores are added to create a composite index with higher scores indicating more functioning although the delimiting of scores differs across versions [14]. In this trial the measurements were conducted at baseline, the post-intervention eight weeks later, and twelve weeks follow-up.
Secondary outcomes:
(1) Pediatric Incontinence and Constipation Scoring System
The Pediatric Incontinence and Constipation Scoring System (PICSS) is an effective instrument of the diagnosis and monitoring of the severity of FI and constipation in children, which has high reliability in the assessment of urinary incontinence and bowel activity [15]. Its construct validity is supported by its correlation with conventional measures of continence and constipation, and is responsive to clinically significant changes over time. The tool is especially useful due to the high incidence of bowel and bladder dysfunction in the pediatric urology clinic [16,17]. Additionally, a number of instruments have high levels of discriminative properties, but few have critically reviewed responsiveness or incorporated patient-reported bother rating, without which a full evaluation of symptom impact is incomplete. An evaluation was performed at baseline, mid-treatment (eight weeks of intervention), and follow-up (12 weeks after the intervention).
(2) Pediatric Quality of Life Inventory
Pediatric Quality of Life Inventory (PedsQL) is a standardized tool that is applied in measuring health-related QOL among children on key domains including physical, emotional, social, and school functioning. The Arabic adaptation has been culturally modified and demonstrated to be dependable, positively valid and responsive to clinical change thus making it appropriate to Arabic-speaking pediatric patients. The assessment periods normally include baseline (pre-intervention), a midpoint assessment (eight weeks of intervention) and follow-up (12 weeks post-intervention) [18].
Intervention protocol
Electrical stimulation
(1) Group A (rectal electrode)
Intrarectal ES was conducted by a rectal pediatric probe that is modeled to reduce cross-infection. The probe was placed at an appropriate depth in the rectum slightly above the AS with the reference electrode at a more proximal position along the rectal wall to maximize dispersion of current and minimize mucosal irritation. A single-channel Chattanooga electrical stimulator (Austin) was used to provide stimulation with a pulse width of 200 µs and a frequency of 35 Hz. The duty cycle was 4 seconds contraction and 12 seconds relaxation (1:3 ratio) and 2 seconds ramp-up and 2 seconds ramp-down time to allow the patient to be comfortable and muscle to be gradually recruited. Intensity was adjusted to 8–15 mA to produce visible or palpable contraction of the pelvic floor muscle without pain to ensure the patient felt no pain, which was verified by both the therapist and the patient. The 15-minute duration of the session was chosen on the basis of previous clinical experience in pelvic floor stimulation in children where session durations are usually reported ranging between 5–30 minutes in order to produce effective neuromuscular response without causing undue patient discomfort and intolerability. Normal precautions of infection-control, such as perineal cleansing, sterile disposable probe use, and high hygiene standards were adhered to. Positioning of patients, checking of electrode positioning, step-wise adjustment of current, constant monitoring of patient comfort, and post-treatment evaluation of hygiene were part of every session. The sessions were three times a week in eight weeks.
Intrarectal ES was done with safety and tolerability in mind due to the pediatric population. A disposable sterile-covered rectal probe of small diameter with a smooth surface was utilized to lessen the discomfort and decrease the risk of infection. Gradual intensity increase, constant therapist supervision, and constant communication between the child and the caregiver in each session ensured acceptability. The adverse events were preemptively observed during the study, such as pain, mucosal irritation, bleeding, or any indication of infection. No side effects were noted and all participants went through the intervention with no complications meaning that under supervision, the rectal ES was well tolerated and clinically safe.
(2) Group B (surface electrode)
The position of the electrodes on the perianal surface was at the 3 o'clock position and 9 o'clock position to the anal border which helped facilitating the flow of current and reducing stimulation of the anal mucosa. The settings used were: one channel output, pulse width of 200 µs and a frequency of 35 Hz. The intensity is adjusted to 8–15 mA depending on patient tolerance and confirmed by palpation or contraction and the intervention delivered thrice per week in eight weeks and each session lasts 40 minutes. At the same time, children were also taught to make voluntary contractions of the AS. Before starting this procedure, perineum is washed using soap and water, hands were disinfected, and single-use and sterile materials were used. The skin is tested on whether it is irritated or not and results recorded as tolerated or not tolerated with continuous evaluation on whether it is painful or intolerable. Sessions were followed by placing the patient in a private, clean environment where a comprehensive observation of the patient was conducted, where the investigator verified the electrode placement and device settings, gradually increase the amperage to a comfortable level to the patient, and a final clean-up was done before documentation.
Anal sphincter exercise program (both groups)
The exercise regime is divided into three parts that were performed during the session to address the various functions of the pelvic floor: MVCs were exercises that involve a contraction of the AS in 5 seconds and a relaxation period of 10 seconds, performed 10 times each set, with 3 sets per session; quick contractions, or quick flicks, involved using rapid contractions of 1-second length with 1-second relaxation, 15 times each set; endurance holds involved using a sustained contraction up to 10 seconds. The exercises were to take place three times a week in an eight-week course.
Biofeedback training (both groups)
Every biofeedback session lasted approximately 40 minutes and had a well-planned procedure to ensure both the safety of the participants and consistency. All sessions were guided by a qualified pediatric physiotherapist who applied a surface electromyography biofeedback equipment (Myo Trace 400 of Medical Measuring Instruments). Electrodes were carefully put around the anal canal (3 o'clock and 9 o'clock positions) with a reference electrode on the left thigh to measure the muscle activity. Foot supports were used to ensure the children were in a comfortable and effective position which resembles a natural defecation position with the hips bent approximately at 90 degrees. Such a position aided in the engagement of pelvic floor muscles. The visual feedback offered to the children during the session came in the form of engaging and animated computer games and made the experience a fun and motivating one.
The preparation time and the time to change the electrodes and to calibrate the system were 5 minutes. The core of the session was various exercises, MVCs for 5 minutes, quick contractions, so-called quick flicks for 5 minutes, and endurance holds for 5 minutes. During these exercises, the children were able to observe their muscle action in the screen which enabled them to know how to shape and train their pelvic floor muscles. Then it came to a short cool-down and eventually a final check, which took approximately 5 minutes. Key information such as the success of the child in adhering to the program and other problems such as pain or skin irritation was documented, which occupied several minutes after each session. To facilitate the continuation of the progress outside the clinic, simple exercises at home were also taught to the children to perform at least 15 minutes a day. These were exercises that comprised of the muscle contractions of 10 seconds and relaxation of 30 seconds, with the parents being the assisting eyes. Compliance was followed up with the daily diaries and frequent check-ups.
The in-clinic program was well designed to assimilate biofeedback with, where applicable, synchronous ES. The exercises were gradually advanced to warm-up then to MVCs, rapid flicks, endurance holds. At home children were advised to do 1 to 3 sets of 10 contractions every day depending on the comfort and age.
Statistical analysis
All the statistical analysis had been performed using SPSS version 26.0 (IBM Corp.). Continuous variables were measured in terms of mean and standard deviation, the frequencies and percentages were used to measure the categorical data. The tests on the normality of distribution were performed with Shapiro-Wilk test. Repeated-measures analysis of variance (ANOVA) was conducted for within-group comparisons at the three time points (baseline, post-intervention, and follow-up). The differences between groups were analyzed using mixed-model ANOVA to obtain the main effect times, group and time×group and what their interaction was. Post-hoc pairwise tests were adjusted to Bonferonni test to identify the source of significant effects. Cohen’s d calculated was used to estimate a pairwise contrast effects, and partial eta squared was used to estimate ANOVA outcomes. Effect sizes for all outcome measures were calculated using Cohen’s d to quantify the magnitude of the intervention effect. Effect sizes were considered small (d≥0.2), medium (d≥0.5) or large (d≥0.8). Furthermore, it can be reported in order to assess clinical relevance in addition to statistical significance. The level of statistical significance considered below 0.05.
RESULTS
Participants
One hundred and ninety children were eligibly screened. Of them, 20 refused to join the study, and 89 patients were evaluated to be included. Among them, 22 of the participants failed to pass the inclusion criteria and were eliminated before the randomization process.
The other 67 eligible subjects were randomly assigned to two treatment groups (34 Group A [rectal electrode stimulation] and 33 Group B [surface electrode stimulation]).
There was no dropout of any of the participants in the treatment period or in the follow-up evaluation and hence all the randomized individuals finished the study and were incorporated in the final analysis.
No side effects of the interventions during the treatment or follow-up were reported. In particular, none of the participants experienced pain, discomfort, skin irritation, and exacerbation of the symptoms.
No significant differences in baseline demographic and anthropometric characteristics of the participants were noted between the two groups. Group A and Group B had a mean age of 8.6±2.7 and 8.9±2.5, respectively. There was also no statistically significant difference between groups in body mass index, body weight, or height (p>0.05).
Sex was equally distributed with the same number of males and females in both groups. Statistical analysis showed that no significant differences in the baseline outcome measures between the rectal and surface electrode conditions were found, which proves that the process of randomization was successful and the likelihood of confounding factors was minimized (Table 1).
Outcomes
Bowel function (BFS)
The BFS showed a significant improvement in both groups after the intervention. The subjects also reported better bowel control and decrease in the frequency of incontinence episodes.
Quality of life (PedsQL)
The two groups showed a significant increase in QOL scores (PedsQL) after the treatment program. Nonetheless, Group A (rectal electrode) showed much higher improvements than the surface electrode group.
The PedsQL scores of post-treatment and follow-up were significantly better in Group A than Group B (p<0.05) reflecting better overall quality of life improvement.
Repeated measures analysis indicated that there was a significant time effect, PedsQL scores improved significantly at the baseline, post treatment and follow-up assessments, indicating both short-term and long-term treatment effects. The effect sizes (both η 2 and partial eta 2) were large, which meant that the changes were significant in clinical terms (Tables 3, 4).
Incontinence severity (PICSS)
The two groups had a substantial decrease in Pediatric Incontinence Clinical Scoring System (PICSS) scores, which depict a lowered frequency and intensity of FI.
The decrease was highly observed in the rectal electrode group where Group A had lower PICSS scores at the post-treatment and follow up than Group B (p<0.05). These results show that rectal electrode stimulation achieved better continence outcomes (Tables 3, 4).
All outcomes were calculated to give effect sizes to supplement the significance testing. In PedsQL, BFS, and PICSS, the rectal electrode group experienced significant effect sizes. The Cohen’s d revealed large time effects (PedsQL 1.21, BFS 1.36, PICSS 1.08) and moderate group (0.51–0.64) and time×group (0.46–0.57) effects, with significant improvements, especially in the intervention group. These results proved that the changes in bowel function, continence, and quality of life were statistically significant but also clinically meaningful.
DISCUSSION
The current research explored the effectiveness differences of rectal electrode and surface electrode ES with sphincter training exercises and biofeedback training in children with FI after TAPTS for HD. Findings showed that both treatment groups had significant improvement of health-related QOL, bowel functioning, and continence score with greater and longer-term improvement in the rectal electrode group. These results underlined the possible importance of rectal stimulation to be applied in a more targeted way and stimulate more specifically the AS and PFM.
The change in PedsQL scores in this study can be attributed to the overall effect of fecal continence on psychosocial health. It has been highlighted in the previous research that children with HD tend to have a poor QOL because their bowel functions remain dysfunctional, and they suffer social embarrassment and bullying [19,20]. Through improved continence, children were relieved physically, enhanced self-esteem, and social inclusion. QOL outcome effect sizes in the current trial were large, which highlighted the clinical significance of changes.
There was a substantial enhancement in the BFS over time, especially in the rectal electrode group. The results were in concurrence with previous reports that neuromodulation and ES have the potential of improving the contractility and endurance of the AS, resulting in improved fecal control [21]. A rectal electrode can generate more local and efficient stimulation of the internal and external AS, and hence, the neuromuscular re-education is facilitated more successfully by the rectal electrode than the surface electrode [22]. This justification is further supported by the differences found between the groups at follow-up.
The PICSS demonstrated the same result of decrease in the severity of the symptoms, indicating that the ES together with sphincter training can be effective in the reduction of incontinence and constipation-related complaints. These findings were consistent with other studies that have reported that a combination of muscular and neuromodulation approaches produces better results relative to a conservative management approach [23].
The current research supported and built on the existing body of literature on the topic of conservative rehabilitation of postoperative FI that is biofeedback, combined with pelvic-floor and AS training has always produced improvement in the continence scores, anorectal manometric measurements, and QOL indices in pediatric patients who still manifest symptoms after anorectal surgery [24].
Our results were consistent with those of Zhang et al., 2022 [25], who recorded improved resting and squeeze pressures after biofeedback in children who had anorectal malformations repaired, and were supported by an extensive review by Caldas Afonso et al., 2024 [26], who defined the mechanistic benefits of neuromuscular re-education. More importantly, this research added new evidence by showing that rectal electrode stimulation, combined with sphincter exercises, provides the best results compared to surface stimulation combined with AS exercises and biofeedback, which proved the increased physiological effectiveness of the rectal modality. These findings were also consistent with adult data (Elsawy et al., 2025 [27]), whereby biofeedback and physiotherapy yielded significant improvements in functional outcomes and QOL after colorectal surgery. All of these findings supported the effectiveness of organized, exercise-based neuromuscular rehabilitation as the initial adjunctive treatment in the postoperative children with HD before the use of invasive interventions.
Direct effect of treatments was supported by comparisons of results between the baseline and post-treatment results, which demonstrated the most significant changes. The effects of treatment did not show instant results but kept on changing over time, in the course of the follow-ups, which is a sign of long-term effects of the treatments. These long-term effects are of clinical importance because the long-term QOL and continence are the most important outcomes in the rehabilitation of children with HD.
An interesting point related to the present study is the continuity of the benefits at the follow-up. The long-term gains indicated that the intervention brings not only short-term benefits, but also makes it possible to induce long-term neuromuscular changes. It is crucial in pediatric populations, where lasting results are a prerequisite to normal growth and social adaptation. Prolonged benefits can also minimize the necessity of repeated interventions that would decrease the burden of treatment among children and families.
The current results showed evident clinical relevance in addition to statistical significance. The extent of the health-related quality of life improvement was marked because the mean improvements in the PedsQL scores in the rectal stimulation group were greater than the previously established minimal clinically important difference in pediatric population. It showed that the changes that had been observed could be not only statistically significant but also significant in terms of patient-centered view. Furthermore, these findings were backed up by functional outcomes, with an increased percent of children in the rectal stimulation group moving to clinically improved continence groups on the basis of BFS and PICSS interpretive thresholds. All of these results indicated that intrarectal ES had clinically significant effects on functional bowel control and overall quality of life after pull-through surgery in HD.
Although the results were promising, a number of shortcomings need to be mentioned. Participants self-reported compliance with home-based sphincter exercises, which might have differed among the participants. These results should be further confirmed in more multicenter trials and objective exercise adherence measures in future research. Besides, a follow-up of the eight-week treatment aided in the determination of the sustainability of the gains into adolescence and adulthood.
The study gave valuable clinical insights as it supported the effectiveness of rectal electrode stimulation as an adjunctive therapy in children with postoperative FI in the rehabilitation phase following HD. Incorporation of these interventions in the rehabilitative procedures of pediatrics can assist in overcoming the physical, the psychological, and social problems related to this HD.
Future studies can include objective monitoring tools, including digital adherence monitoring, to make the research more accurate. A sham-stimulation or no-treatment control group was not used in the study, and this could have prevented the separation of the particular contribution of ES with the effect of placebo or natural recovery. These weaknesses should be overcome in future research by using larger and more heterogeneous samples, extending the follow-up period, and by providing strong control conditions. Moreover, the further investigation of the most effective stimulation plans, electrode shapes, and combinations with behavioral therapy might be used to optimize specific rehabilitation protocols. Investigations on patient and caregiver experience would also be valuable to find out the real-life acceptability and long adherence.
Conclusion
This study had shown that ES, especially through rectal electrodes, is an effective treatment of bowel motility, continence and quality of life in children undergoing a corrective surgery to treat HD. Tolerance of the intervention was high and the benefits were long-term at follow-up. Additional support of neuromuscular re-education and functional outcome was provided by incorporating AS exercises and biofeedback training. The inclusion of these modalities in the conventional rehabilitation strategies can help maximize the long-term outcomes and psychosocial growth.
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