Anoplasty for Fused Anus Following Fournier’s Gangrene Debridement: a Case Report

Anal stenosis is a rare debilitating surgical condition that secondary to functional and anatomical causes. Excisional hemorrhoidectomy is the leading anatomical cause of anal stenosis, affecting up to 87.7% of cases. The severity and level of the impacted region determines the management options considered. Numerous tension-free anoplasty techniques and their varying success rates have been reported in the literature. A patient-tailored anoplasty approach highly depends on the level of severity, location, and extent of anal stenosis. We present herein the management of a case of fused anus three years following extensive surgical debridement for Fournier’s Gangrene. A colonoscopy illumination guided neo-anal creation was performed, which resulted in low severe anal stenosis six weeks later. Subsequently, V-Y anoplasty, lateral internal sphincterotomy, and colostomy closure were performed, which demonstrated good initial recovery. However, six months later, the anal stenosis recurred. Diamond-shaped anoplasty was offered, but the patient refused any further surgical intervention. This case report aims to highlight the rare complication of fused anal stenosis and its management. The clinical management challenge and learning experience are reported. Additionally, it is recommended that such rare complications be managed in a tertiary center, using a multidisciplinary approach led by an experienced colorectal surgery sub-specialty unit.


Introduction
Anal stenosis is a debilitating condition, and a technically challenging scenario, secondary to functional and anatomical causes [1,2]. Excisional hemorrhoidectomy is the leading anatomical cause of anal stenosis, affecting 87.7% of patients [3]. The incidence of anal stricture following open hemorrhoidectomy is reported in less than 4% of cases, with a mean presentation of symptoms 6 weeks following the procedure [4]. The condition relates to extensive surgical excision of the anoderm and chronic inflammation of the region. It is associated with poor quality of life among affected patients, with symptoms that mimic obstructive defecating syndrome. Multiple anoplasty techniques and their outcomes have been described in the literature. Anoplasty can be performed via a tension-free simple advancement flap, or a full-thickness advancement flap [5]. The fundamental approach to the successful management of anal stenosis is to assess the severity, location, and extent of the lesion, in order to determine a tailored anoplasty approach [1]. We present the management of a case of fused anus 3 years following extensive Fournier's gangrene debridement. There exists only one other reported case of complete anal stenosis following Fournier's gangrene debridement, which was managed by means of a V-Y anoplasty and colostomy closure [6].

Case Presentation
A 44-year-old male presented with a 1-week history of painful scrotal swelling, perianal pus discharge, and fever. He has hypertension, dyslipidemia, and ischemic heart disease and underwent angioplasty 5 years prior. A physical examination revealed foul-smelling necrotic scrotal skin with pus discharge This article is part of the Topical Collection on Surgery * Jothinathan Muniandy jothinathan84@gmail.com from the perianal region. Laboratory results indicated a total white blood count of 26.2 X 10 9 /L (normal range 4-11 × 10 9 / L) and compensated metabolic acidosis. A clinical diagnosis of Fournier's gangrene was carried out. The patient was resuscitated, and a broad-spectrum antibiotic treatment was initiated. Urgent surgical debridement was performed around the scrotum and perianal region, which extended into the sphincter complex. Sigmoid loop colostomy was performed to prevent feces from soiling into the wound. The wound was managed by the wound care team and healed with secondary intention. During review at the outpatient follow-up, healing with secondary intention resulted in a fused anus (Fig. 1). The patient was referred to a colorectal team for management of the fused anus 3 years later.
An MRI of the pelvis showed intact external and internal anal sphincter integrity (Fig. 2). A preoperative distal loop colonoscopy did not reveal any evidence of a rectal stricture (Fig. 3). Colonoscopy illumination guided neo-anal creation was performed following excision of the cicatricial tissue in a circular fashion using a blade. Full-thickness suture of the anal skin to the anoderm was performed using interrupted polyglactin 3/0 (Fig. 4). The patient was discharged after being informed and educated about the self-anal dilatation technique. We reviewed the patient weekly and planned for an early colostomy reversal.
A neo-anal creation was complicated, with severe anal stenosis 6 weeks later. Examination under anesthesia, V-Y anoplasty, and lateral internal sphincterotomy were performed (Fig. 5). Subsequently, the anal canal was restored, and colostomy reversal was performed.
He was able to bowel open, without fecal or gas incontinence. After 5 months, he complained of straining to evacuate. He had developed recurrent anal stenosis 6 months following anoplasty (Fig. 6). We offered the option of diamond or house-shaped anoplasty, but he refused any further procedure, as he was able to empty his bowel with small separate hard lump stool.

Discussion
Anal stenosis is a rare debilitating surgical condition that is secondary to functional or anatomical causes [1,2]. Functional anal stenosis is common due to the hypertonic internal anal sphincter, whereas anatomical anal stenosis is typically the result of an anorectal surgery complication [2]. Anatomical anal canal stenosis occurs due to extensive excision of normal anoderm, which heals with inelastic tissue. Anal stenosis most commonly arises post-hemorrhoidectomy and has been reported in up to 87.7% of cases [1,3]. Other causes of anatomical anal stenosis are complication of ultralow anterior resection, pelvic tumor radiotherapy, and extensive anal warts excision.
Extensive debridement is of paramount importance in Fournier's gangrene. A high index of suspicion of anal stenosis is necessary to follow up, mostly when debridement of circumferential anoderm was performed. Fused anus as a result of cicatricial complication was inevitable in our case. Diversion colostomy may have partly resulted in a fused anus, following secondary healing. Okumura et al. (2017) have reported the only other case report of complete anal stenosis following Fournier's gangrene debridement, during which V-Y anoplasty was performed with initial anal stenosis on examination, without significant symptoms, which recovered on long-term follow-up [6].
The presentation of anal stenosis may mimic obstructive defecating syndrome symptoms, and some may present with pruritis ani and bleeding. In our case, the presentation was masked due to the presence of diversion colostomy. The severity and classified level of anal stenosis anatomical proximity from the dentate line would determine the basis of our treatment and management [1,3]. Non-operative measures such as dilatation and stool softener may be effective initially in mild and moderate stenosis but would eventually require surgical intervention in due course [1,3]. Surgical management of anal stenosis should not be performed during the active phase of healing. Ideally, a matured scar is required for surgical reconstruction. Before definitive anoplasty, it is essential to assess the anorectal column via endoscopy and the anal sphincter by means of an endoanal ultrasound or MRI.
Management of anal stenosis following an anorectal procedure is challenging, primarily due to anoderm scarring. There are many anoplasty methods described with varying success rates. Although some anoplasty techniques are easily performed with a high success rate, reconstruction experience is required to achieve a desirable outcome. A patient-tailored anoplasty approach is fundamental, depending on the severity, location, and extent of anal stenosis [1].
Y-V advancement anoplasty is replicable, with a long-term success rate of over 85% [2,7]. V-Y anoplasty is an alternative method wherein the triangle V base flap is advanced to the pectinate (dentate) line and sutured. There is a risk of the possibility of flap ischemia, especially the tip. Therefore, careful dissection along the subcutaneous fat and pedicle is crucial [2]. For severe low anal stenosis, the Milson et al. (1986) treatment approach was V-Y anoplasty, with a 90% good outcome. However, when there is lack of anoderm, an advancement flap with sphincterotomy is recommended for higher stenosis [3].
To the best of our experience, V-Y anoplasty with lateral internal sphincterotomy is not an ideal method, primarily due to the circumferential nature of stenosis. Duieb et al. (2010) described an algorithm approach for tension-free anoplasty repair, which modifies Y-V to diamond flap and, if necessary, to bilateral diamond flap [5]. A tailored rhomboid mucocutaneous advancement flap on 50 patients by Gallo et al. (2020) reported a success rate of 96%, with no recurrence. A bilateral advancement flap was performed for three patients, as an anal caliber was not satisfactory after the unilateral procedure [8].  Only one recurrence was reported in the case of the house advancement flap after 1 year [9]. Other advancement flaps have a greater advantage in comparison to V-Y and Y-V anoplasty, as they provide significant flap mobility and advancement into the anal canal.
Neo-anal creation with anoplasty and concurrent stoma reversal may produce a desirable outcome and reduce the risk of anal stenosis, due to the restoration of gastrointestinal continuity. Delay in colostomy closure was among the contributing factors to recurrent anal stenosis.

Conclusion
Anal stenosis is a debilitating and challenging condition. A patient-tailored anoplasty approach is crucial, depending on the level of severity, location, and extent of anal stenosis. Circumferential anal stenosis should be managed by either bilateral diamond or rhomboid, or house advancement flap, by an experienced reconstructive surgeon.
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Authors' Contributions JM was involved in clinical care, conceptualization, and drafting of the manuscript. FH was involved in clinical care, revision of the manuscript for intellectual content, and for its approval. TYS was involved for checking the important intellectual content in the manuscript. All the authors read and approved the final version of the manuscript.
Funding No funding received.
Data Availability Not applicable.

Declarations
Ethics Approval The case report is in line with the local ethics protocol.
Consent to Participate Patient participation is entirely voluntary for this case report.
Consent for Publication Consent was obtained from patient for publication of this case report and accompanying images.

Conflict of Interest
The authors declare no competing interests.