Immunohistochemical confirmation of the presence of smooth muscle in the normal neonatal anorectum and in neonates with anorectal malformations

Relation between the internal anal sphincter and defecation disorders in patients with anorectal malformations

OBJECTIVES

To investigate associations between the rectoanal inhibitory reflex (RAIR), type of congenital anorectal malformations (ARMs), type of operation that patients with ARM had undergone, and objectively measured fecal incontinence and defecation problems.

METHODS

We retrospectively included 69 pediatric patients with ARM. All underwent anorectal function tests at the University Medical Center of Groningen during the last 10 years. We assessed anorectal physiology using the Rome IV criteria and anorectal function tests.

RESULTS

We found the reflex in 67% of patients and all types of ARMs. All patients who had not been operated on, and those who had undergone less extensive surgery possessed the reflex. In contrast, patients who underwent posterior sagittal anorectoplasty, 44% possessed it. We found no difference between mean rectal volumes in patients with and without the reflex (251 mL vs. 325 mL, respectively, p = 0.266). We found that over time, patients without the reflex seemed to develop significantly higher rectal volumes than patients who had it. We did not find a significant difference between the reflex and fecal incontinence; however, it seems that the absence of the reflex, resting anal sphincter pressure, and fecal incontinence are related.

CONCLUSION

The RAIR seems present in patients with ARM irrespective of their malformation type. Corrective surgery, however, may impair this reflex. Seemingly, its absence results in constipation with enlarged rectal volumes and fecal incontinence. Every effort should be made to preserve this reflex during surgery and to use extensive surgical procedures as sparingly as possible.

Diagnosing Mild Forms of Anorectal Malformation With Anorectal Manometry: A Prospective Study

INTRODUCTION

Rectoperineal congenital anorectal malformations (CARMs) are diagnosed by examining the perineum, combined with electric stimulation (ES) of the anal sphincter performed under anesthesia. This procedure may be troublesome because it is based on the observed contractibility of the sphincter. We aimed to add 3-dimensional high-resolution anorectal manometry (3D-HRAM) to the procedure and to assess its value for diagnosing rectoperineal forms of CARM.

METHODS

We prospectively included 66 patients younger than 24 months who presented with constipation and were suspected of CARM, idiopathic constipation, or Hirschsprung disease. The patients were assessed between 2015 and 2021 at University Medical Center Groningen, the Netherlands. All patients underwent 3D-HRAM, followed by the standard diagnostic procedure for either CARM or Hirschsprung disease.

RESULTS

Of the 51 patients who underwent both 3D-HRAM and ES, we observed that patients with rectoperineal CARM revealed a pressure gap along the anterior part of the anal sphincter. Based on this observation, we diagnosed 35 patients with CARM. Subsequently, all 35 diagnoses were confirmed with ES. Sixteen patients were diagnosed as not having CARM, 100% of whom were in agreement with the gold standard-ES. Both the specificity and sensitivity of 3D-HRAM for diagnosing rectoperineal CARM were 100%.

DISCUSSION

We consider 3D-HRAM a reliable tool for diagnosing and excluding rectoperineal CARM. Using this method in patients suspected of CARM might keep infants from undergoing unnecessary interventions requiring anesthetics, such as ES. By providing objective insight into the functional capabilities of the anal sphincter, anorectal manometry adds to the diagnosis.

Pelvic Floor Muscles Contribution in Surgical Outcome of Children with High-type Anorectal Malformations

As a consequence of high-type anorectal malformations (ARMs) pathogenesis, the pelvic floor muscles remain severely underdeveloped or hypoplastic, the rectal pouch is located at the level or above the puborectalis sling, and the bowel terminates outside the sphincter muscle complex support. For children with high-type ARMs the ultimate objective of therapy is mainly to grow up having bowel continence function that is compatible with a good quality of life, and the final prognosis depends significantly on the grade of development of pelvic floor muscles and the successful entering of the anorectum fully within the support of the external anal sphincter due to intraoperative conservation of the puborectalis sling. Pelvic magnetic resonance imaging (MRI) has recently become the preferred imaging study for prediction of functional outcomes, since it can define the anatomy and evaluate the development of the sphincteric muscles before and after surgical correction. Based on recent literature and our clinical experience, we will discuss the relevance of pelvic floor muscles MRI to the clinical outcome of children with high type ARMs.

Mechanical Compression of Coverslipped Tissue Sections During Heat-induced Antigen Retrieval Prevents Section Detachment and Preserves Tissue Morphology

Heat-induced antigen retrieval (HIAR) is routinely employed on aldehyde-fixed tissue sections to enhance the reactivity of antibodies that exhibit weak or no specific interactions with tissue antigens when applied in conventional immunohistochemical protocols. A major drawback of HIAR protocols is, however, the heat-induced detachment of sections from the microscope slide with resultant impaired tissue morphology or loss of the section. We developed a method in which tissue sections mounted on glass slides are temporally coverslipped, and a clamp is used to compress the sections on the microscope slide during HIAR treatment. This "pressurized coverslipping" during HIAR was tested on various formalin-fixed tissues (murine kidneys and temporal bones, human tonsils and temporal bones) that were embedded in paraffin or celloidin. The method reliably kept the sections adherent to the slide, preserved the tissue morphology, and effectively retrieved tissue antigens for improved results in immunohistochemical labeling, even for exceptionally delicate, large, and poorly adhering sections, that is, decalcified human temporal bone sections. In summary, we present a simple method for improved slide adherence and morphological preservation of tissue sections during HIAR treatment that can be combined with all HIAR protocols and that requires only basic lab equipment.

Histology with immunohistochemistry of the fistula region in female anorectal malformation: Can it be used for neo-anus reconstruction?

AIM

Female anorectal malformation is characterised by communication to the exterior by a fistula. There are conflicting reports of the presence of normal anus in the fistula region. This study was undertaken to assess the histopathology and immunohistochemical correlation of the terminal portion of the fistula in female patients and suitability of fistula incorporation in the reconstruction of the neo-anus.

METHODS

This prospective study included 13 patients of female anorectal malformation. Of these, seven had a vestibular fistula (VF), and the rest had an anterior ectopic anus (AEA). Histopathology of the fistula region was undertaken, along with immunohistochemistry. Various findings were evaluated.

RESULTS

Of seven VF patients, four showed atrophic or disrupted internal sphincter smooth muscle, whereas the remaining three showed hypertropic internal sphincteric smooth muscle. Six patients showed hypertrophic nerve bundle. Five VF patients showed subepithelial fibrosis, and none of them showed ganglion cells. Of six patients of AEA, internal sphincteric smooth muscle was normal in five. It was hypertrophic in one patient. Transitional epithelium was present in four patients. All patients showed hypertrophic nerve bundle and aganglionosis. Subepithelial fibrosis was observed in six patients.

CONCLUSION

The fistula region in VF and AEA patients appears to be an abnormal structure. Rather than preservation of the terminal fistulous region, resection followed by anoplasty may be a viable option.

Pre- and postoperative rectal manometric assessment of patients with anorectal malformations: should we preserve the fistula?

BACKGROUND

Surgical correction of congenital anorectal malformations could be complicated by fecal incontinence. Some authors believe that preservation of the fistula is associated with improved outcome. Rectal manometry is a well-established method to evaluate postoperative functional outcome in these patients and can demonstrate successful transplantation of the fistula.

OBJECTIVE

Herein, we report the results of our series of patients with anorectal malformations and an externally accessible fistula, who underwent pre- and postoperative rectal manometry studies.

DESIGN

This is a prospective cohort study.

SETTINGS

This study was conducted at a tertiary neonatal and pediatric surgical center.

PATIENTS

Patients with anorectal malformations, who underwent preoperative rectal manometry of the fistula and postoperative rectal manometry of the neoanus between January 2002 and December 2011 were included.

MAIN OUTCOME MEASURES

Pre- and postoperative rectal manometry results were compared by using paired t test or contingency tables (p values <0.05).

RESULTS

Twelve female patients with rectoperineal (n = 7, 58%) or rectovestibular (n = 5, 42%) fistula were treated by anterior sagittal anorectoplasty or minimal posterior sagittal anorectoplasty. Complete transposition of the fistula was achieved in all patients. Normal presence of rectoanal inhibitory reflex was demonstrated in all pre- and postoperative rectal manometry studies. There were no differences between pre- and postoperative rectal manometry in the length of the high-pressure zone (2.3 ± 0.6 cm vs 2.5 ± 0.8 cm (p = 0.5)) and resting pressure (59.4 ± 18.2 mm Hg vs 62.1 ± 19.2 mm Hg (p = 0.62)). At a median follow-up of 665 days (range, 290-1165 days), all patients have voluntary bowel movements, with no incontinence or soiling.

LIMITATIONS

This study is limited by its small sample size and by single-institution bias.

CONCLUSION

Preoperative rectal manometry of rectoperineal or rectovestibular fistula showed the presence of functional anal structures within the fistula in all patients. We speculate that fistula-preserving surgery in patients with anorectal malformations is associated with improved bowel function outcome.