The Long-Term Post-Surgical Outcome of Intermediate Anorectal Malformation in Our Department

doi:10.21203/rs.3.rs-4841867/v1

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The Long-Term Post-Surgical Outcome of Intermediate Anorectal Malformation in Our Department

https://doi.org/10.21203/rs.3.rs-4841867/v1

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published 23 Sep, 2024

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Background: Posterior sagittal anorectoplasty and laparoscopic-assisted anorectal pull-through are preferred for anorectal malformation (ARM) today, while careful pull-through procedures with sacroperineal approach yield excellent outcomes. This study focuses on a pull-through procedure emphasizing continence mechanism preservation and compares outcomes with historical studies with various procedures.

Methods: Bowel function of patients with intermediate ARM followed up for over 10 years post-surgically was assessed. Data collected included ARM type with the Krickenbeck classification, comorbidities, complications, post-surgical examinations, follow-up, and bowel function at the latest clinic visit. The literature review collected original articles including more than 10 post-anorectoplasty cases which were followed for over 10 years.

Results: Eleven cases were identified, with a median age at anorectoplasty and follow-up length of 6.9 months and 14.4 years. Two fistula recurrences required surgical treatment. Long-term incontinence and constipation were observed in 9% and 45% of the cohort, respectively. Good rectal angulation and a positive rectoanal inhibitory reflex were confirmed in most cases examined. A literature review identified eight studies with various outcome measuring instruments.

Conclusion: Outcomes of the introduced pull-through procedure were favorable, while the literature review highlights the variation in outcomes of various anorectoplasty.

Evidence Level: Level IV

Anorectal malformation

Posterior sagittal anorectoplasty

Prognosis

fecal incontinence

Fecal incontinence is a major long-term morbidity of anorectal malformation (ARM) after anorectoplasty. Prior to the introduction of posterior sagittal anorectoplasty (PSARP) in 1981, only 7.5% of patients achieved complete postoperative fecal continence in a large case series.[1] PSARP allowed precise anatomical visualization around the fistula and facilitated the correct positioning of the pull-through rectum in the muscle complex. As a result, the procedure contributed to reduce the incidence of long-term postoperative fecal incontinence to 60–70% in cases of intermediate ARM.[2, 3] Recently, laparoscopic-assisted anorectal pull-through (LAARP) has gained popularity.[4] At the same time, our institution still favors the rectal pull-through with sacroperineal approach. We advocate three key steps aimed at preventing post-surgical long-term incontinence.[5] These consist of a relatively generous skin incision with Nixon’s skin flaps, preservation of the internal sphincter, and the placement of the pull-through rectum in the muscle complex under direct observation (Fig. 1). [6] The aim of this article is to describe the details of the procedure and the long-term post-surgical outcomes of bowel function, including fecal incontinence and constipation. Furthermore, original articles on the long-term outcomes of various anorectoplasty procedures for high or intermediate ARM were reviewed to compare the outcome of the current procedure with historical cohorts subjected to different anorectoplasty techniques.

1.1. Anorectoplasty

All patients had undergone colostomy in the neonatal period. Colonoscopy was performed distal to the colostomy in the theater at anorectoplasty, and a guidewire was passed through the fistula to the external urethral meatus in males or the fistula opening in females (Fig. 2A). The colonoscope was kept in place during anorectoplasty to aid in locating and dissecting the rectum. A urethral catheter was inserted. The patient was placed in the jack-knife position, and a nerve stimulator was used to determine the center of the external sphincter. A skin incision from the coccyx to the perineum was made and skin flaps were created following Nixon’s anoplasty (Fig. 2B).[6] The dissection around the posterior rectal wall was limited in the midline, while the muscle complex was left intact (Fig. 2C). The distal end of the rectum was encircled just outside the urethra or the vagina with assistance of the guidewire. The most distal end of the fistula was divided to preserve as much of the internal sphincter around the rectum as possible (Fig. 2D). Subsequently, the total length of the muscle complex was exposed and the rectum could be placed in the center of the complex under direct observation. A Penrose drain was inserted into the muscle complex and the tract was widened with a Hegar dilator before pulling the rectum down into the complex (Fig. 2E). The rectal seromuscular layer and the external sphincter were fixed with four stitches, and anoplasty was completed (Fig. 2F).

Post-surgical contrast enema is performed before the closure of the colostomy to confirm the formation of anterior rectal angulation. Anorectal manometry is usually performed during adolescence.

1.2 Patients and data collection

The study was approved by the institutional review board of Kanazawa Medical University (Reference # I- 769). A minimal post-surgical observation period was set for 10 years, so this study included patients with intermediate ARM who underwent anorectoplasty in the period from 2000, when a new medical recording system was installed in our hospital, and completed clinical observations for more than 10 years. The following pre-operative and surgical data were collected: type of ARM described by the Krickenbeck classification, associated conditions, sacral ratio, age at the anorectoplasty, and surgical complications. The following post-surgical data were reviewed: duration of postoperative follow-up, age after completing toilet training, and bowel functions assessed by the Krickenbeck classification at the last outpatient clinic during the study period.[7] Results of post-surgical contrast enema and anorectal manometry were also collected when they were available.

1.3 Literature search

The literature search was conducted on MEDLINE using the following keywords: 'Anorectal malformation OR Anorectal malformations AND Constipation OR Fecal incontinence.' The search was limited to papers written in English and published between January 1, 1960, and June 30, 2023. Duplicates were removed, and eligibility was assessed based on the following inclusion criteria: original articles discussing the prevalence of constipation or fecal incontinence in patients treated for high or intermediate ARM during infancy and followed up for more than 10 years. Cloacal malformation cases were excluded. Review articles, conference abstracts, and case reports with fewer than 10 patients were also excluded. Articles that did not include a description of the original procedures for ARM were excluded as well.

2.1 The current cohort

Eleven patients with intermediate ARM who underwent anorectoplasty and post-surgical observation for more than 10 years were identified (Table 1). Rectourethral bulbar fistulas were observed in seven patients, and rectovaginal fistulas were observed in one patient based on the Krickenbeck classification. The remaining three patients had ARM without a fistula. Three patients had congenital cardiac diseases, while urogenital anomalies and gastrointestinal comorbidities were observed in three patients, respectively. Two patients were confirmed to have chromosomal anomalies, including trisomy 21 and 22q11.2 deletion syndrome. A tethered spinal cord was seen in one patient. Growth hormone deficiency was seen in one patient. The sacral ratio ranged from 0.67 to 1.01. All but one patient had a sacral ratio of 0.7 or larger. The median age at the anorectoplasty was 6.9 months (3.5–28.2 months). From the viewpoint of complications, two patients underwent surgical treatment for fistula recurrence, and one patient was treated for mucosal prolapse. The median follow-up period was 14.4 years (11.5–17.7 years). Postoperative contrast enema results were available for review in six patients, with five examinations revealing good anterior rectal angulation. Anorectal manometry results were available in four patients, with three cases showing a positive rectoanal inhibitory reflex (RAIR). Anal canal pressure ranged from 24 to 40 cmH2O and the values were considered within a normal range. The completion of toilet training was confirmed at a median age of 4.8 years. Bowel function at the final follow-up was classified as Krickenbeck grade 1 fecal incontinence in one patient (1/11 patients, 9.0%), while six patients (5/11 patients, 45.4%) had grade 2 constipation. Voluntary bowel movement was confirmed in all patients.

2.2 Literature Reviewing

Eight articles were identified and categorized in Table 2 depending on the type of anorectoplasty performed (Table 2).[8-15] Two studies involved multiple procedures: pull-through and PSARP, and PSARP and LAARP. Hence, the study populations and the outcomes for each procedure were described separately in the relevant sections of the table.[11, 15] All studies included both high and intermediate ARM, and the population of each type of ARM was described in the table if available. The age of patients ranged from 10 to around 40 years old. The assessment tools used in the reviewed studies were grouped into two types: numerical scoring systems developed by Kelly, Holschneider, Rintala, and Japanese Study Group for ARM, and categorial classifications reported as Krickenbeck and Wingspread classification. The rates of incontinence varied widely, ranging from 5% to 100% across the studies, while constipation was observed in 21% to 62% of cohorts. Additionally, the mean or median values of the numerical scoring instruments in the reviewed studies showed significant variation.

Faecal continence is maintained by the complex interaction of the pelvic nerve and sphincter mechanisms in normal status, while this system has been reported as innately underdeveloped in ARM.[7, 16] To protect this mechanism, we have advocated sacroperineal approach pull-through procedures with three important steps. [5] The first step involves limited dissection confined in the midline of the rectum to minimize damage to pelvic nerves entering from the lateral side. This concept is similar to that of PSARP, but we adopt skin flaps from Nixon’s anoplasty.[6] The primary benefit of this procedure is its ability to achieve better exposure around the distal end of the rectum and the muscle complex with less dissection around the rectum. Additionally, the flaps can be anastomosed with the pull-through rectum in the muscle complex, thereby reducing the need for extensive rectal dissection to pull the rectum down to the perineum for anastomosis. Furthermore, there is a cosmetic advantage as the newly created anus is tucked into the intergluteal cleft (Fig. 3A/B). The second step involves preserving the internal sphincter muscle around the distal rectum. Internal anal sphincter-saving posterior sagittal anorectoplasty has been shown to maintain a higher resting tone and the presence of RAIR, believed to contribute to improved feces holding activity.[17, 18] In the current cohort, RAIR was confirmed in four out of five patients who underwent post-surgical manometry, implicating the preservation of adequate mechanisms for the activity. The final step involves direct visualization of the muscle complex from the puborectalis muscle to the external sphincter. This is achieved through generous skin incisions adopted from Nixon’s anoplasty, enabling precise positioning of the pull-through rectum within the muscle complex. A similar procedure, known as "muscle complex-saving PSARP," has been recently reported, with several advantages to traditional PSARP.[19] Firstly, it is believed to offer the best opportunity to preserve the existing continence mechanism, which could be negatively influenced by cutting the midline of the muscle complex during PSARP.[20] Secondly, it is asserted to facilitate the creation of good anterior rectal angulation, as demonstrated in the current cohort (Fig. 3C).

In literature review, eight studies contained sufficient data that met the inclusion criteria for comparison with the outcomes of the current cohort. Regarding the instruments used for evaluation of the outcomes of anorectoplasty, both numerical scorings and categorical classifications were used in these studies and no single dominant instrument was observed.[7, 16, 18, 21, 22] Numerical scorings seems to be beneficial to describe the change of functional outcome over time, whereas categorical classifications are better suited for describing the prevalence of incontinence or constipation at a designated time point. No consensus has been reached regarding the superiority of one single instrument over the others.[23]

Compared to the reviewed studies, particularly those employing pull-through procedures, the current cohort experienced a significantly lower incidence of post-surgical incontinence. This difference could be attributed to the strict adherence to the three steps aimed at preserving the sphincter mechanism as much as possible. The incidence rate is lower than that reported in LAARP by Wong et al. and was comparable to the rate with PSARP by Hassett et al., which was the best outcome in PSARP among the reviewed studies.[13, 15] On the other hand, the incidence of constipation was nearly 50% in the current cohort, possibly due to the careful preservation of the feces holding mechanism. We would like to justify this phenomenon from the viewpoint that constipation is relatively manageable and socially acceptable compared to incontinence unless it causes overflow soiling.

At the same time, the current result should be interpreted with caution. Firstly, our cohort was limited in the patients with intermediate ARM, whereas all reviewed articles included patients with high and intermediate ARM. Thus, a direct comparison of the current results with these historical cohorts was impossible. For example, Rintala and Iwai noted significantly better functional outcomes in patients with intermediate ARM compared to those with high ARM in their sub-group analysis.[8, 9] Secondly, the chronological difference in the study period of reviewed articles cannot be ignored. The studies including pull-through procedures tended to be published earlier than those including other procedures. Advancements of technology, such as electric stimulators, and improved anatomical understanding of ARM might have positively impacted on the outcomes of later studies and the current cohorts, which included patients who underwent anorectoplasty after 2000. Thirdly, post-surgical examinations including contrast enemas and manometry have not been completed in all patients in the current study.

Finally, it is essential to address the two cases of recurrence of rectourethral fistula. The most challenging aspect of our anorectoplasty procedure lies in encircling the rectourethral fistula from the dorsal side of the rectum. Levitt and Pena noted the absence of a layer amenable for blunt dissection between the fistula and the urethra, which increases the risk of urethral damage during dissection.[24] To mitigate this risk, we adopted the insertion of a guidewire into the fistula along with a catheter in the urethra. This approach facilitated easier identification of the distal rectum and the urethra, then reduced the incidence of urethral damage. Additionally, we leave a colonoscope in the distal end of the rectum during anorectoplasty to precisely locate the distal end of the rectum from the inside. This technique enables surgeons to safely encircle the rectum approximately 1 cm proximal to its end and subsequently dissect the remaining rectum toward the fistula.

The study presented a favorable long-term continence outcome in patients with intermediate ARM by employing pull-through procedures focusing on the preservation of continence mechanisms. A literature review on the long-term outcome after anorectoplasty for high or intermediate ARM highlighted the presence of multiple assessment tools and significant variation in the outcomes.

Financial support/Conflicts of interest: All authors have no financial support or conflicts of interest regarding the manuscript.

Ethics approval: The study was approved by the institutional review board of Kanazawa Medical University (Reference # I- 769).

Author contributions: All authors contributed to the study conception and design. Data collection and analysis were performed by Ryo Tamura. The first draft of the manuscript was written by Ryo Tamura and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

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Tables 1 to 2 are available in the Supplementary Files section

No competing interests reported.

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Journal Publication

published 23 Sep, 2024

Read the published version in Pediatric Surgery International →

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You are reading this latest preprint version

The Long-Term Post-Surgical Outcome of Intermediate Anorectal Malformation in Our Department

Status:

Journal Publication

Version 1

Abstract

Figures

Introduction

Methods

1.1. Anorectoplasty

1.2 Patients and data collection

1.3 Literature search

Results

Discussion

Conclusion

Declarations

References

Tables

Additional Declarations

Supplementary Files

Status:

Journal Publication

Version 1