Segmental colonic motility in patients with anorectal malformations

State of the Art Bowel Management for Pediatric Colorectal Problems: Anorectal Malformations

Up to 79% of patients with anorectal malformations (ARMs) experience constipation and/or soiling after a primary posterior sagittal anoplasty (PSARP) and are referred to a bowel management program. We aim to report the recent updates in evaluating and managing these patients as part of the manuscript series on the current bowel management protocols for patients with colorectal diseases (ARMs, Hirschsprung disease, functional constipation, and spinal anomalies). The unique anatomic features of ARM patients, such as maldeveloped sphincter complex, impaired anal sensation, and associated spine and sacrum anomalies, indicate their bowel management plan. The evaluation includes an examination under anesthesia and a contrast study to exclude anatomic causes of poor bowel function. The potential for bowel control is discussed with the families based on the ARM index calculated from the quality of the spine and sacrum. The bowel management options include laxatives, rectal enemas, transanal irrigations, and antegrade continence enemas. In ARM patients, stool softeners should be avoided as they can worsen soiling.

Dyssynergic patterns of defecation in constipated adolescents and young adults with anorectal malformations

We aimed to evaluate the etiologies of constipation in patients with anorectal malformations having a good prognosis for bowel control but a high risk of constipation. We included twenty-five patients from the Odense university hospital in Denmark. Patients were subjected to colon transit time examination and high resolution anorectal manometry (HRAM). The median age was 18 (14–24) and 48% (12/25) were females. Fifty-two % (13/25) of patients were diagnosed with constipation. Types of anorectal malformation were perineal fistula (9/25), rectovestibular fistula (8/25), rectourethral bulbar fistula (5/25) and no fistula (3/25). No difference in neither total colon transit time nor segmental colon transit times were found based on the presence of constipation. Only four of the constipated patients fulfilled criteria for dyssynergic defecation with a dyssynergic pattern at HRAM and prolonged colon transit time. A Type I dyssynergic pattern was dominant in constipated patients (7/13). A Dyssynergic defecation pattern was due to isolated contraction of puborectalis muscle in 9 out of 13constipated patients. We found a dyssynergic pattern during attempted defecation in patients with anorectal malformations disregarded the presence of constipation. In the majority of constipated patients an isolated contraction of the puborectalis muscle was visualized with HRAM.

Motility disorders in infants

Gastrointestinal motility disorders are common in the pediatric population and may affect the entire gastrointestinal tract and can vary from mild to severe conditions. They may clinically manifest as gastro-esophageal reflux symptoms, feeding difficulties and failure to thrive, constipation and diarrhea amongst others. This review first highlights the embryologic development of the gastrointestinal tract, after which the prenatal and neonatal development of gastrointestinal motility is discussed. Normal motility patterns as seen in (preterm) infants are described as a background for the discussion of the most common congenital and acquired motility disorders in infancy. This review specifically focuses on the role of preterm birth on the development of these disorders.

Long-term bowel function, quality of life and sexual function in patients with anorectal malformations treated during the PSARP era

Anorectal malformations are an important group of congenital anomalies that vary widely in their anatomical characteristics and complexity. Understanding the long-term functional outcomes after modern treatments, and how these compare to the general population, are essential for ensuring that patients receive optimal, evidence-based care. With increasing appreciation of the wider impact of the illness on patients and their families, minimizing social disability from fecal incontinence and enabling normal social integration from the outset are key management concerns. This review summarizes the current knowledge on the functional outcomes by type of malformation, reflecting on the literature, and our institutional experience over a follow-up period of nearly 30 years.

Outcome in anorectal malformation type rectovesical fistula: a nationwide cohort study in The Netherlands

PURPOSE

Outcomes of patients with an ARM-type rectovesical fistula are scarcely reported in medical literature. This study evaluates associated congenital anomalies and long-term colorectal and urological outcome in this group of ARM-patients.

METHODS

A retrospective Dutch cohort study on patients treated between 1983 and 2014 was performed. Associated congenital anomalies were documented, and colorectal and urological outcome recorded at five and ten years of follow-up.

RESULTS

Eighteen patients were included, with a mean follow-up of 10.8years. Associated congenital anomalies were observed in 89% of the patients, 61% considered a VACTERL-association. Total sacral agenesis was present in 17% of our patients. At five and ten years follow-up voluntary bowel movements were described in 80% and 50%, constipation in 80% and 87%, and soiling in 42% and 63% of the patients, respectively. Bowel management was needed in 90% and one patient had a definitive colostomy. PSARP was the surgical reconstructive procedure in 83%. Urological outcome showed 14 patients (81%) to be continent. No kidney transplantations were needed.

CONCLUSION

In our national cohort of ARM-patients type rectovesical fistula that included a significant proportion of patients with major sacral anomalies, the vast majority remained reliant on bowel management to be clean after ten years follow-up, despite "modern" PSARP-repair. Continence for urine is achieved in the majority of patients, and end-stage kidney failure is rare.

Wnt5a expression in the hindgut of fetal rats with chemically induced anorectal malformations--studies in the ETU rat model

PURPOSE

Wnt5a is involved in the initiating and patterning morphological adaptations of gut. However, its role remained unknown during terminal hindgut development in the normal and anorectal malformation (ARM) rat embryos. This study was designed to investigate the expression pattern of Wnt5a in the terminal hindgut in ARM rat embryos.

MATERIALS AND METHODS

Ethylenethiourea-induced ARM model was introduced to investigate the expression pattern of Wnt5a during terminal hindgut development using immunohistochemical staining, reverse transcriptase polymerase chain reaction (RT-PCR), and Western blot analysis.

RESULTS

Immunostaining revealed that Wnt5a expression showed space-dependent changes in the developing terminal hindgut. On embryonic day 17 (E17) in normal embryos, the Wnt5a protein was initially expressed in the mesenchyme of the terminal hindgut. From E18 to 19, the positive staining cells gradually increased. The expression was detected mainly in the circular muscle and myenteric plexus of hindgut. In the ARM embryos, on E17, the Wnt5a protein was also expressed in the hindgut. However, from E18 to 19, the positive staining cells in the middle hindgut gradually increased but in the terminal hindgut decreased. In Western blot and RT-PCR, time-dependent changes of Wnt5a protein and mRNA expression were remarkable during the terminal hindgut development in normal and ARM embryos.

CONCLUSION

These data implied that the downregulation of Wnt5a at the time of hindgut neuromuscular development might partly be related to the maldevelopment of terminal hindgut in ARM.

Megarectum after surgery for anorectal malformations

PURPOSE

Megarectum complicating surgery for anorectal malformation (ARM) has implications for long-term continence. Factors influencing continence and defecation include intact rectal reservoir, innervation/proprioception of the anorectal muscle complex, functioning anorectal inhibitory reflex (AIR), and intact perception at the anal margin. We studied outcomes after surgery for ARM with emphasis on megarectum; particularly as to whether altered rectal proprioception from anatomic sacrococcygeal anomalies affect incidence. We also assessed whether an abnormal AIR could trigger passive rectal dilatation without mechanical obstruction.

METHODS

Eighty six infants (53 male) with ARM over 20 years were included. Demographics, surgical history, pathology, defecation patterns, imaging, manometry, and morbidity were analyzed. Incidence of sacrococcygeal malformations in children with and without megarectum was compared using Fisher exact test. Manometry results were evaluated for integrity of AIR and correlated to megarectum occurrence.

RESULTS

There were 23 high/intermediate and 63 low ARMs. Fourteen (16%) developed a megarectum: 6 of 23 in high and 8 of 63 in low anomalies (P = .33). Twelve patients underwent megarectum resection at a median of 2.6 years (7 months to 10 years); 2 received bowel management protocols. Fifty-seven percent (8/14) of children with and 7% (5/72) without megarectum had sacrovertebral anomalies (P = .0001). Patients with preoperative manometry (n = 5) demonstrated an intact AIR. Colonic manometry demonstrated hyperactive colons (n = 2). Constipation was the predominant preoperative symptom; 3 patients suffered from incontinence after resection. All the specimens showed normal innervation and thickened muscularis on pathology.

CONCLUSIONS

Sacral anomalies, which are more prevalent in children who developed megarectum, may result in abnormal rectal proprioception contributing to this pathology. Innervation anomalies may coexist, although preoperative manometries showed normal AIRs. Rectal dysmotility may lead to stool retention with subsequent dilatation, and patients who underwent colonic manometry had diffuse colonic hypermotility. Further physiologic and cellular studies are needed to elucidate the causes of this significant complication after surgical ARM repair in the absence of obstruction.

Colonic motility and functional assessment of the patients with anorectal malformations according to Krickenbeck consensus

BACKGROUND/PURPOSE

In this study, the patients operated on for anorectal malformations (ARM) were evaluated in terms of segmental (SCTT) and total colonic transit times (TCTT) and clinical status according to Krickenbeck consensus before and after treatments.

METHODS

Forty-one patients with ARM (28 males/13 females) older than 3 years (median age, 7.7 years; range, 3-25) who had no therapy before were assessed for voluntary bowel movements (VBM), soiling (from 1 to 3), and constipation (from 1 to 3), retrospectively. Distribution of the patients were rectourethral fistula (17), perineal fistula (PF; 8), vestibular fistula (VF; 8), cloaca (3), rectovesical fistula (1), rectovaginal fistula (1), pouch colon with colovestibular fistula (1), no fistula (1), and unknown (1). The patients ingested daily 20 radiopaque markers for 3 days, followed by a single abdominal x-ray on days 4 and 7 if needed. The results were compared with the reference values in the literature.

RESULTS

Mean follow-up period was 36 months (range, 1-108.5 months). All patients but 1 had soiling in different degrees. Twenty-one patients who had VBM were divided into group 1, with constipation (n = 9), and group 2, without constipation (n = 12). The other 19 patients who had no VBM were divided into group 3, with constipation (n = 14), and group 4, without constipation (n = 5). The longest TCTT and rectosigmoid SCTT were found in group 3 (69.5 and 35.2 hours, respectively). Group 1 had long SCTT in rectosigmoid but normal TCTT (27.8 and 47.4 hours, respectively). Groups 2 and 4 had normal SCTT and TCTT, and there was no significant difference between them. After the appropriate treatment, of the patients, 45% (18/40) had no soiling, and the soiling score decreased to grade 1 in 27.5% (11/40) and to grade 2 in 10% (4/40). Four had unchanged soiling score, and 3 were excluded from the study because of follow-up problems. Half of the patients in group 3 (4 VF, 2 rectourethral fistula, PF) gained VBM without soiling after laxative treatment. Only four of 23 patients had decreased constipation score (2 cloaca, PF, VF).

CONCLUSIONS

In this study, ARM patients complaining of constipation with or without VBM had prolonged SCTT in the rectosigmoid region. Percentage of the improvement in soiling scores was more conspicuous than that of constipation scores. The dismal figure observed at the first examination in the assessment of VBM was not associated with an unfavorable improvement with laxative treatment. So, it is suggested that assessment of VBM initially may be deceptive for clinical status.

Effect of bowel transection and fecal passage deprivation on the enteric nervous system in neonatal rats

INTRODUCTION

A temporary stoma is a relatively common procedure at the neonatal age for a number of disorders. At birth, the enteric nervous system (ENS) is not fully developed; temporary colostomy causes morphological changes in the ENS. We studied whether transection of bowel or deprivation of stool is responsible for these changes. Moreover, reversibility of the ENS changes after stoma closure was investigated.

METHODS

Male Lewis rats aged 3 weeks were randomly divided into 3 groups. Group 1 (stoma group) received a stoma (t = 0), stoma closure 2 weeks later (t = 1), and were killed 2 weeks after stoma closure; group 2 (transection group) had a colon transection and immediate anastomosis (t = 0) and were killed 2 weeks afterward. Group 3 (sham group) had no operation. In all groups, the nerve/muscle fiber ratio (NMR) in the proximal and distal colon was assessed with full thickness biopsy specimens at operation or after killing. The NMR in the stoma, transection, and sham group at t = 1 were used to assess the effect of deprivation of passage of feces and transection itself on the development of the ENS of the colon. Results of the stoma group at t = 1 and t = 2 were compared to assess possible reversibility of ENS changes after stoma closure.

RESULTS

There was a significantly higher NMR in the distal colon compared to the proximal colon in both the stoma and transection groups at t = 1 (2.0 +/- 0.38, P < .001 and 2.8 +/- 0.97, P < .001, respectively), whereas there was no significant difference in NMR ratio at t = 1 (1.1 +/- 0.18, P = .34) in group 3. In group 1, the NMR ratio increased further after stoma closure to 3.1 +/- 0.37, P < .001, at t = 2.

CONCLUSION

Transection of the bowel rather than deprivation of fecal passage causes nerve fiber hypertrophy in the distal colon of neonatal rats. Restoration of bowel continuity does not result in recovery of these ENS changes.

Imperforate anus: long- and short-term outcome

Anorectal malformations are common anomalies observed in neonates. Survival of these babies is currently achieved in most cases and improvements in operative technique, patient care, and better follow-up have led to improved functional results. A new, simplified classification system (Krickenbeck classification) and method of functional assessment has led to an improved understanding of these anomalies and has allowed for a better comparison of outcomes. Following successful anatomical repair and appropriate programs of bowel care, socially acceptable continence can be achieved in a majority of patients, especially those with an intact sacrum.

The contribution of the sonic hedgehog cascade in the development of the enteric nervous system in fetal rats with anorectal malformations

OBJECTIVE

This study was designed to determine the expression of Sonic hedgehog (Shh) and its downstream genes during development of the enteric nervous system (ENS) in ethylenethiourea (ETU)-exposed fetal rats with anorectal malformations (ARMs).

MATERIAL AND METHODS

Anorectal malformations were induced by 1% ETU (125 mg/kg) given on gestational day 10, and the litter was harvested at term. The fetal anorectum and rectosigmoid region, including any communication with the urinary tract, were collected for gene expression studies and immunofluorescence study of the ENS. Gene expression of Shh cascade was performed using reverse transcription and real-time polymerase chain reaction (PCR). The myenteric plexuses of the ENS in normal and ARM rats were visualized with fluorescent antibodies.

RESULTS

Reverse transcription-PCR confirmed expression of Shh and its target genes in all parts of the ARMs. Quantitative PCR demonstrated that levels of expression of the genes of the Shh cascade were low in the ARMs. The immunoreactivity of neuromarkers was markedly reduced in high ARMs and slightly reduced in low ARMs.

CONCLUSION

This study demonstrates reduced expression of Shh and its target genes in ARMs in ETU-exposed fetal rats. Neurons in the myenteric plexus were decreased in high and low types of ARMs. Our results support a role for the Shh cascade during development of the ENS during hindgut development.

Scintigraphic evaluation of colonic motility in patients with anorectal malformations and constipation

BACKGROUND AND PURPOSE

Constipation is one of the major sequelae in patients after correction of anorectal anomalies (ARAs). The aim of the present work has been to assess the colonic transit time, using radioisotope scintigraphy, in patients operated for ARA and experiencing constipation in the follow-up. The results were compared with transit time from children with true functional constipation.

METHODS

Twelve or 32 patients operated for ARA during the period 1994-2003 experienced mild or severe constipation (6 with high or intermediate form of ARA and 6 with low type) at follow-up. The mean age of this group was 5.8 years. Eighteen patients, mean age 6.7 years, with true functional constipation were studied as well. Colonic transit times were investigated using radioisotope scintigraphy. Normal values for colonic transit time were derived from historical controls. Radioisotope diethylenetriamine pentaacetic acid labelled with indium 111 was administered orally to determine a segmental colonic transit. Images of the abdomen have been taken at 6, 24, 48, and again at 72 hours, if radioactivity was not cleared from the colon. To quantify colonic transit, we calculated the geometric centre (GC) dividing the colon into anatomic regions.

RESULTS

According to normal controls, 2 different type of delayed transit can be observed: (a) slow-transit constipation if GC at 48 hours is less than 4.1; (b) functional rectosigmoid obstruction (FRSO) if GC at 48 hours is 4.1 or more but less than 6.1 at 72 hours. Patients with functional constipation were divided into 2 groups: (a) slow-transit constipation in 12 patients with a GC at 48 hours of 3.7 +/- 0.5; (b) FRSO in 6 patients with a GC of 4.7 +/- 0.04 and 5.02 at 48 and 72 hours, respectively. Patients operated for high ARA had values characteristic of FRSO with GC at 48 hours of 5.1 +/- 0.8 and 4.75 +/- 0.5 at 72 hours. In low ARA, the transit times were similar to the ones observed in patients with high ARA at 48 hours with a GC of 4.9 +/- 0.5.

CONCLUSIONS

Patients with ARA frequently have functional sequelae in the postoperative period such as constipation. According to our results, constipation seems to be secondary to segmental motility disorders limited to the rectosigmoid area, similar to constipated children with FRSO. No evidence of more generalised motility disturbance, as previously postulated, could be recorded.

Signs and symptoms of slow-transit constipation versus functional retention

BACKGROUND/PURPOSE

Slow-transit constipation (STC) has been described recently in children. This retrospective study correlated symptoms, signs, transit times, and immunohistochemistry to determine the diagnostic differences between STC and functional fecal retention (FFR).

METHODS

One hundred eighty children with intractable constipation underwent clinical assessment, nuclear transit study (NTS), with or without laparoscopic colonic muscle biopsy. Patients were divided by NTS into those with STC and those with FFR. Parents completed questionnaires on presenting symptoms.

RESULTS

In 161 patients with STC and 19 with FFR, there were no differences in gender, gestation, or timing of symptom onset. Over 20% had the first meconium delayed more than 24 hours after birth even in FFR (4 of 19). Bloating and soiling were more common in STC. There were no differences between patients with STC but different histology on biopsy. More STC patients had soft stools (39%) than FFR (16%), and a lower stool frequency of less than once a week (STC 26% compared with 11% FFR). FFR was managed more often with medication or diet alone (53%) compared with STC (29%), where enemas, lavage, or surgery were more common.

CONCLUSIONS

Children with STC showed similar symptoms and signs to those with FFR, but more had bloating and soiling, softer stools, and longer intervals between bowel actions. Delayed meconium stool beyond 24 hours after birth was common in both groups. Diagnosis of STC or FFR required NTS and was not possible on symptoms alone.

Fecal incontinence in anorectal malformations, neuropathy, and miscellaneous conditions

In the majority cases, fecal soiling in children is functional and usually associated with severe constipation. Fortunately, functional soiling is a self-limiting problem and usually disappears at puberty. Organic fecal incontinence is a consequence of congenital malformations affecting the anorectum, anal sphincters, or the spinal cord. Inability to control bowel function may be permanent, as in patients with myelodysplasia; self-limiting, as in patients who have fecal soiling after a pull-through operation for Hirschsprung's disease; or partial, as in many patients who have undergone repair of an anorectal malformation. The purpose of this report is to review the etiology, long-term outcome, and evolution of the management of different types of organic fecal incontinence in children. Knowledge of the pathophysiology of fecal incontinence has accumulated during recent decades, and this provides the basis of modern treatment modalities that have revolutionized treatment so that today most patients can be provided total or at least social continence from early childhood.

Posterior sagittal approach: megasigmoid resection and anal reconstruction for severe constipation and fecal incontinence after anoplasty

PURPOSE

The aim of this study was to present the technique of megasigmoid resection and anal reconstruction by complete posterior sagittal approach for the children with severe constipation and fecal incontinence after anoplasty.

METHODS

Six patients (age, 2 to 18 years) born with imperforate anus and originally treated with perineal anoplasty suffered from intractable constipation and fecal incontinence. Contrast enema showed massive dilated and aperistaltic rectosigmoid colon with fecal impaction. Resection of the dilated bowel and anal reconstruction were completely performed by posterior sagittal approach.

RESULTS

The mean operating time was 205 minutes (range, 125 to 265 minutes) and the average length of resected colon was 23.3 cm (range, 10 to 40 cm). There were no intraoperative or postoperative complications. By 2 to 4 months after the operation, all patients obtained voluntary bowel movement. On follow-up at 6 to 24 months postoperative, no patient had constipation or required use of the laxatives again. Four of 6 patients suffered from grade 1 soiling, and the other 2 had grade greater than 1 soiling. None had urinary retention or incontinence after the procedure.

CONCLUSION

Resection of dilated rectosigmoid colon and anal reconstruction for the patients with severe constipation and fecal incontinence after anoplasty can be performed successfully using a posterior sagittal approach.

Colonic motility in children with repaired imperforate anus

Following surgical correction of imperforate anus, voluntary bowel control is frequently poor because of abnormal anorectal function. Using colonic manometry we investigated the role of colonic motility in the pathogenesis of fecal soiling in children following imperforate anus repair. Thirteen children with repaired imperforate anus and fecal soiling underwent motility testing 2-12 years after anoplasty. All had fecal incontinence unresponsive to conventional medical treatment. Colonic manometry was performed using water-perfused catheters. Anorectal manometry was undertaken in 10 patients. Motility study results, treatment and outcomes were compared. All patients had high-amplitude propagating contractions (HAPCs) with an average of 80% propagation into the neorectum. There was no correlation between HAPC number or morphology and any variable. Internal anal sphincter resting pressure was low in 6/10 patients. Relaxation of the internal anal sphincter was present in 6/10 children. Only 1 of 5 patients able to cooperate was capable of generating a normal maximal squeeze pressure. Therapeutic regimens were changed in 11 patients with clinical improvement in five. Fecal soiling in patients with repaired imperforate anus is a multifactorial problem including propagation of excessive numbers of HAPCs into the neorectum as well as internal anal sphincter dysfunction. Colonic manometry in conjunction with anorectal manometry aids in the understanding of the pathophysiology of fecal soiling and guides clinical management in children with repaired imperforate anus.

Posterior sagittal anorectoplasty is superior to sacroperineal-sacroabdominoperineal pull-through: a long-term follow-up study in boys with high anorectal anomalies

BACKGROUND/PURPOSE

It is unclear which surgical method offers best long-term functional results in patients with high anorectal anomalies. The purpose of this study was to compare the long-term outcome of sacroperineal-sacroabdominoperineal pull-through (SP-SAP) to that of posterior sagittal anorectoplasty (PSARP).

METHODS

Only boys with high anorectal anomalies (rectourethral fistula) were included in the study to get fully comparable patient groups. From 1975 to 1987, 36 consecutive patients underwent anorectal reconstruction: 19 had SP-SAP (1975 to 1983) and 17 PSARP (12 with internal sphincter-sparing technique, 1983 to 1987). The late bowel function (age at follow up, SP-SAP, 19 years; range, 15 to 22; PSARP, 13 years; range, 10 to 19) was evaluated by clinical interview and examination, and anorectal manometry.

RESULTS

Six (35%) of the PSARP patients and one (5%) of the SP-SAP patients (P < .04) were always clean without any adjunctive measures. Three PSARP patients and two SP-SAP patients stayed clean with daily enemas. In the PSARP patients with soiling, the median frequency of soiling episodes in a month was four (range, 1 to 16), in the SP-SAP patients, 20 (range, 2 to 28, P < .001). None of the SP-SAP patients but 8 of 17 of the PSARP patients had constipation requiring diet or oral medication. Two PSARP patients and four SP-SAP patients had occasional faecal accidents. The median daily bowel movements in the PSARP group was one (range, one to four) and in the SP-SAP group, three (range, one to five, P < .001). The PSARP patients had significantly higher anorectal resting and squeeze pressures and voluntary sphincter force (cm/H2O, PSARP: mean resting, 47+/-9; mean squeeze, 106+/-29; mean voluntary sphincter force, 60+/-22; SP/SAP: mean resting, 27+/-10; mean squeeze, 68+/-22; mean voluntary sphincter force, 41+/-17; P < .01). Thirteen (76%) of the 17 PSARP patients and none of SP-SAP patients had positive rectoanal reflex indicating functional internal sphincter.

CONCLUSIONS

In boys with high anorectal anomalies, PSARP clearly is superior to sacroperineal and sacroabdominoperineal pull-through in terms of long-term bowel function and faecal continence.

Abnormal colonic interstitial cells of Cajal in children with anorectal malformations

BACKGROUND/PURPOSE

Constipation is a frequent functional problem in children after operation for all types of anorectal malformations. Although this has been assumed to be caused by hypomotility of the rectosigmoid colon, recent studies have demonstrated generalized colonic hypomotility in children with high or intermediate anomalies. The cause of this disorder is unknown. The aim of this study was to determine whether the observed colonic hypomotility seen in patients with anorectal malformations was caused by defects in distribution or density of interstitial cells of Cajal (ICC), recently identified as 'intestinal pacemaker cells'.

METHODS

Colostomy specimens from 12 patients with high anorectal anomalies (ARM group; age 0 to 14 months) were compared with colostomy specimens from five control patients with nonmotility-related gastrointestinal pathology (age, 1 to 4 months). Specimens were immunohistochemically labelled with antibodies to PGP9.5, a marker for neural tissue, and antibodies to c-kit, a recently characterized marker for interstitial cells of Cajal (ICC).

RESULTS

Ganglion cells were present in all histological specimens. Abnormalities in distribution and density of c-kit-positive ICC were present in 7 of 12 ARM patients. In two ARM patients, ICC were completely absent, and in five patients, ICC density was markedly reduced in circular muscle and at the submucosal border of circular muscle. Only five ARM patients had a distribution of ICC similar to that of control patients.

CONCLUSION

Defects in the population of intestinal pacemaker cells may underlie the colonic hypomotility seen in high anorectal malformations and hence may contribute to refractory constipation.