Enhanced Approach to Treating Chronic Anal Fissures: Fissurectomy with Vertical Non-full-thickness Midline Sphincterotomy and Mucosal Advancement Flap

Abstract

Objectives:

Lateral internal sphincterotomy is a conventional surgical intervention for chronic anal fissures, yet the potential for postoperative anal incontinence underscores the need for an alternative approach. This study aimed to evaluate the outcomes of patients with chronic fissures who underwent a combination of fissurectomy, vertical non-full thickness midline sphincterotomy (VNMS), and mucosal advancement flap (MAF), as a means of mitigating the risk of incontinence.

Methods:

This retrospective analysis included forty-six consecutive patients with chronic anal fissures, unresponsive to topical diltiazem, who underwent fissurectomy combined with VNMS and MAF between April 2018 and May 2023. Primary outcome measures encompassed fissure healing rates. Continence was assessed using the Fecal Incontinence Severity Index (FISI), and manometric assessments were conducted before the procedure and three months postoperatively.

Results:

With a median follow-up of 27 months, there were no postoperative complications, and the overall fissure healing rate reached 96% (44/46). At three months post-procedure, FISI scores were reduced to 0, with no instances of fecal soiling. Anal resting pressure exhibited a significant reduction at 3 months [pre-op: 133 (95% CI, 128−150) vs. 3 mo: 109 (95% CI, 100−117) cmH₂O; p = 0.01]. Similarly, maximum anal squeeze pressure showed a significant decrease three months post-surgery [pre-op: 317 cmH₂O (95% CI, 294−380) vs. 3 mo: 291 cmH₂O (95% CI, 276−359), p = 0.03].

Conclusions:

The combination of fissurectomy, VNMS, and MAF proved to be an effective approach for chronic anal fissures, yielding favorable medium-term outcomes without postoperative anal incontinence.

Introduction

Anal fissure represents a prevalent anal disorder characterized by intense pain during and post defecation, coupled with bleeding and pruritus, leading to a notable decline in overall quality of life[1]. Chronic anal fissure (CAF) is distinguished by fibrotic changes in the fissure margins, the presence of a sentinel tag, and an enlarged anal papilla. This condition commonly associates with spasm within the internal anal sphincter (IAS), potentially leading to local ischemia and hindering the natural healing process[2]. Alleviating the IAS spasm is pivotal for pain relief and remission and can be achieved through surgical or chemical sphincterotomy. Lateral internal sphincterotomy (LIS) has conventionally stood as the primary treatment for CAF, involving the division of the IAS from its distal to either the proximal end of the fissure or the dentate line. While the overall healing rates after LIS stand at an impressive 94%, it's noteworthy that there's a reported risk of anal incontinence ranging from 3.4% to 4.4%, which could significantly impact the patient's well-being[3-5].

Recently, there has been a growing interest in sphincter-sparing surgical approaches, including techniques like fissurectomy and anal advancement flap. Fissurectomy entails the excision of the underlying fissure, converting a chronic condition into an acute one while preserving the structural integrity of the IAS complex. However, simple fissurectomy has demonstrated a recurrence rate of 11.6%[6]. Conversely, anal advancement flap involves the transplantation of well-vascularized, healthy tissue onto the fissure base and, when combined with fissurectomy, shows promise in promoting wound healing[7]. Nonetheless, the latter technique tends to encounter more frequent wound complications due to its increased tissue dissection and mobilization, alongside an extended operative duration[8].

Previous attempts have involved combining fissurectomy with posterior midline sphincterotomy, although this approach can lead to the development of an unfavorable “key-hole” deformity of the anal canal, potentially causing fecal soiling[9-11]. This deformity, while occasionally arising as a late complication of CAF, can have lasting implications[12]. Similarly, combining fissurectomy with chemical sphincterotomy has been explored to encourage healing by resecting fibrosis and reducing anal hypertonia[13,14]. However, this approach has been associated with a notable recurrence rate[14]. A preliminary series of cases involving fissurectomy combined with vertical non-full-thickness midline sphincterotomy (VNMS) demonstrated promising outcomes, boasting a high cure rate of 96% (25 out of 26 cases), and notably avoiding the “key-hole” deformity[15]. It's important to note that one of the successfully treated patients from this series experienced anal stenosis due to scarring-induced healing, necessitating reoperation.

Building upon this prior work, the combination of fissurectomy with VNMS and mucosal advancement flap (MAF) emerged as a strategy aimed at not only suppressing anal hypertonia and reducing the risk of scarring and stenosis but also preventing the “key-hole” deformity. This study endeavors to comprehensively assess the safety and efficacy of the fissurectomy, VNMS, and MAF hybrid approach in the therapeutic management of chronic anal fissure.

Methods

Patients

Selection criteria

Consecutive patients diagnosed with chronic anal fissures (CAF) and treated by a single proctologist at the district hospital from April 2018 through May 2023 were included in the primary cohort. Inclusion criteria were the presence of bleeding and pain during and immediately after defecation, along with typical mid-line anal fissures characterized by fibrotic edges, with or without a sentinel skin tag and hypertrophied anal papilla. Patients with non-midline or non-linear ulcers, inflammatory bowel disease (IBD), or HIV infection were excluded from the study. Fissures occurring in lateral positions should raise suspicious for other disease processes, such as Crohn's disease, tuberculosis, syphilis, HIV/AIDS, or anal carcinoma[3], which naturally require a disease-oriented treatment.

A total of 134 patients with CAF, who had not weak anal sphincter function based on anal manometric examination, were enrolled for a minimum 6-week course of medical therapy. This involved the application of 2% diltiazem gel twice daily to the anal canal's edge and inner region[1]. Additionally, patients experiencing constipation were provided with stool softeners. After a 2-month follow-up period, 51 patients with non-healed or recurrent fissures became eligible for the study. Among them, 46 patients opted for surgical intervention. Anal continence was evaluated using the Fecal Incontinence Severity Index (FISI) score[16]. This study was approved by the regional Ethics Committee (approved number 22-049-230707). Information of the study protocol was made public, and patients were ensured that they could withdraw consent. However, no patients or their relatives subsequently refused to participate in the study.

Surgical procedure

ALL surgical procedures were performed by A.T., a specialist in coloproctology, under spinal anesthesia. Patients with posterior fissures were positioned lithotomy style, while those with anterior fissures were placed in the prone jackknife position. Following fissure examination using a bivalve speculum, diathermy was employed to excise fibrotic edges. A triangular section of perineal skin was removed at the fissure's distal edge to expose the distal edge of the IAS and measure its thickness (Figure 1). If present, a sentinel skin tag or hypertrophied anal papilla was excised. Vertical division of the IAS on the fissure was performed from the lower edge of the IAS to the fissure apex. Gradual, uniform division of the IAS was carried out using a No. 15 knife blade, ensuring consistent depth along the original vertical incision (Figure 2). The process continued until approximately half of the original IAS thickness remained, which was confirmed while the thickness of remaining IAS was inspected along a horizontal direction (Figure 2a). Subsequently, MAF was performed, namely the anorectal mucosa above the fissure apex was mobilized proximally, advanced distally, and sutured to the subcutaneous external sphincter or intersphincteric groove (Figure 5). For patients with fissures on both anterior and posterior sides, fissurectomy combined with VNMS and MAF were performed on the more significant lesion, while the other lesion underwent fissurectomy and MAF. In cases of fissure-associated fistulas, fistulotomy and non-full-thickness vertical division of the remaining IAS on the fissure were executed (Figure 3, 4). Throughout surgery, the speculum was maintained at a diameter of 3 cm or less and positioned for no longer than 30 minutes.

Figure 1.

The distal edge of internal anal sphincter was exposed following the excision of a triangle piece of perineal skin. a, internal anal sphincter; b, excised perineal skin.

Figure 2.

Approximately, half thickness of the internal anal sphincter was divided vertically up to the fissure apex. a, divided internal anal sphincter; b, the fissure apex.

Figure 5.

The mobilized anorectal mucosa above the fissure apex was sutured to the intersphincteric groove. a, anorectal mucosa; b, intersphincteric groove.

Figure 3.

a: The fissure was associated with fistula. a, fistula probe; b, sentinel skin tag. b: The fistula involved the internal anal sphincter. a, internal anal sphincter.

Figure 4.

a: Following fistulotomy, the remaining internal anal sphincter on the fissure was exposed. a, internal anal sphincter. b: The vertical non-full-thickness division of the remaining internal anal sphincter on the fissure with fistulotomy was performed. a, divided internal anal sphincter; b, wound at fistulotomy.

Assessments and follow-up

Clinical follow-up

Monthly outpatient follow-up examinations were conducted until all the wounds healing completely. Three months post-surgery, anal continence was evaluated using the FISI score. Further clinical follow-up was tailored to patients' preferences or symptom severity, involving in-person visits or phone consultations. The primary outcome measures were both the resolution of pain and bleeding symptoms, and wound healing confirmed on the physical examination, while postoperative complications and recurrence were recorded.

Anorectal manometry

Anorectal manometry was performed both before and 3 months after surgery. Examinations were conducted with the patient in the left lateral position, without prior bowel preparation. Anal pressure was assessed using air-charged catheters (Urodynamic System Solar, Edaptechnomed Co. Ltd, Tokyo)[17].

Statistical analysis

All data analyses were performed using the SPSS™ statistical software package (SPSS, Chicago, IL, USA). Continuous variables were compared using the Wilcoxon signed rank test for paired data, and categoric variables were compared using the Chi-squared test or the Fisher's exact test. The results are expressed as the median and 95% confidence interval (CI). A value of p < 0.05 was considered statistically significant.

Results

Patient demographics and anal fissure details are summarized in Table 1. Among the 46 patients included in the study, there were 30 men and 16 women with a median age of 50 years (95% CI, 48−55 years). The distribution of fissure locations was as follows: 30 patients had a posterior midline fissure, 9 had an anterior fissure, and 7 had fissures on both sides. Among these patients, 12 were diagnosed with a fistula beneath the fissure, situated within 4−5 mm of the distal edge of the IAS. No significant differences in age, sex distribution, fissure location, or symptom duration were observed between patients in Group 1 (fissure without fistula) and Group 2 (fissure associated with fistula).

Table 1.

Patients and Fissure Characteristics.

		Total	Fissure without fistula	Fissure associated fistula	p valuea
No. of patients		46	34	12
Age, years		50 (48-55)	50 (48-57)	49 (39-57)	0.41
Sex
	Male	30	22	8	1.00
	Female	16	12	4
Presenting symptoms
	Pain	44	32	12	0.39
	Bleeding	39	27	11	0.34
	Constipation	21	17	4	0.32
Fissure position
	Posterior	30	19	11	0.07
	Anterior	9	8	1
	Both sides	7	7	0
Duration of symptoms, months		12 (31-86)	12 (34-107)	15 (5-47)	0.81

Values are presented as n or median (95% confidence interval)

^aMann-Whitney U test

The median operative time was 32 minutes (95% CI, 32−39 minutes). In Group 1, five patients underwent additional anal procedures, including two with hemorrhoidectomy and three with rubber band ligation. In Group 2, one patient underwent rubber band ligation simultaneously with the primary procedure. Patients stayed in the hospital for a median of 2 days (95% CI, 2.0-2.8 days), and the median follow-up period was 27 months (95% CI, 20−29 months). Surgical interventions in Group 2 involved fistulotomy and vertical non-full-thickness division of the remaining IAS along the fissure. No postoperative complications or instances of “key-hole” deformity were recorded. Fissure healing was achieved in 96% (44/46) of patients, typically within a median of 9 weeks after the procedure. Figure 6 shows the postoperative image in the patient who underwent surgery for a posterior fissure associated with fistula. There were no statistically significant differences in operative duration, blood loss, hospital stay, or healing time between the two groups (Table 2).

Figure 6.

Postoperative image in the patient with a posterior fissure associated with fistula who underwent fistulotomy, a combination of fissurectomy, vertical non-full thickness midline sphincterotomy, and mucosal advancement flap. arrow, posterior side.

Table 2.

Operative Data.

	Total	Fissure without fistula	Fissure associated fistula	p valuea
No. of patients	46	34	12
Operating time, min	32 (32-39)	32 (31-40)	38 (29-45)	0.82
Blood loss, ml	5 (4-6)	4 (4-6)	5 (3-8)	0.58
Hospital stay, days	2 (2.0-2.8)	2 (2.1-2.4)	2 (1.4-4.3)	0.56
Healing time, weeks	9 (9-11) (n=44)	9 (9-11) (n=33)	9 (7-11) (n=11)	0.49

Values are presented as n or median (95% confidence interval)

^aMann-Whitney U test

All patients presented with anal pain or bleeding prior to surgery. Following the procedure, 44 patients experienced complete resolution of their symptoms, while two remained symptomatic due to unhealed fissures. One (Group 1) of the two patients who had persistent bleeding three months after surgery was then treated with 2% diltiazem gel for 8 weeks and his fissure cured subsequently. Another patient (Group 2) had persistent anal pain and bleeding postoperatively.

A total of 32 patients (70%) underwent pre- and post-operative manometric studies, as presented in Table 3. The maximum anal resting pressure showed a significant reduction three months after surgery [133 cmH2O (95% CI, 128−150) vs. 109 cmH2O (95% CI, 100−117), p < 0.001], along with a decrease in maximum anal squeeze pressure [317 cmH2O (95% CI, 294−380) vs. 291 cmH2O (95% CI, 276−359), p = 0.03]. In Group 1, resting pressure significantly decreased three months post-surgery. The FISI score did not exhibit a significant change after surgery [0 (95% CI, -0.3−0.8) vs. 0 (95% CI, 0−0)].

Table 3.

Manometric Measurements before and 3 Months after Surgery.

Anal pressure, cmH2O		Total (n=32)	Fissure without fistula (n=24)	Fissure associated fistula (n=8)
Resting pressure
	Before	133 (128-150)	141 (132-159)	119 (107-132)
	After	109 (100-117)a	111 (101-120)a	93 (81-126)
Squeeze pressure
	Before	317 (294-380)	336 (304-405)	274 (193-378)
	After	291 (276-359)b	307 (283-383)	267 (189-352)

Values are presented as median (95% confidence interval)

^ap < 0.0001, ^bp = 0.03 vs. before (Wilcoxon signed-rank test)

Discussion

This study underscores the remarkable efficacy of combining VNMS and MAF, resulting in an impressive healing rate of 96% over a median follow-up period of 27 months. The procedural safety profile was favorable, with minimal morbidity, and only two instances of non-healing fissures postoperatively, which was subsequently resolved through chemical sphincterotomy in one of the two patients.

The distinct advantage of VNMS lies in its ability to avoid the need for a complete vertical division of the IAS akin to Lateral Internal Sphincterotomy (LIS), which potentially reduces the risk of incontinence. Notably, the VNMS technique avoids the “key-hole” deformity of the anal canal and the associated fecal soiling that can follow posterior midline sphincterotomy[10-12]. Additional benefits were realized by addressing concurrent issues during fissurectomy, such as the excision of lateral fissure margins, sentinel tags, and hypertrophied papillae. These measures were implemented to counteract the primary concerns associated with recurrence post-sphincterotomy[18].

Comparatively, fissurectomy combined with anal advancement flap has demonstrated efficacy as a sphincter-sparing procedure, yielding a significantly lower rate of anal incontinence when contrasted with LIS[9]. The rationale underlying the anal advancement flap procedure centers on infusing fresh blood supply to the fissure's ischemic region, thereby promoting perineal wound healing. Nevertheless, complications such as wound infection and donor site breakdown have been documented with this approach[8,9,19]. In contrast, fissurectomy combined with MAF emerges as a viable alternative that preserves sphincter function without exacerbating anal incontinence[20,21]. Noteworthy advantages of this approach include faster healing, reduced risk of stenosis, and diminished postoperative pain. The avoidance of flap separation, necrosis, and donor site issues further enhance its appeal.

However, recent evidence highlights challenges in achieving consistent success rates with fissurectomy combined with MAF, as some cases experienced recurrence shortly after surgery[22]. We also experienced one of three patients who underwent fissurectomy combined with MAF occurred non-healed fissure postoperatively (data not shown). This suggests that the integration of MAF might not uniformly improve postoperative wound healing. In our study, the median healing time for patients undergoing fissurectomy with VNMS and MAF was approximately 9 weeks, comparable to outcomes achieved with fissurectomy and VNMS alone in a prior study[15]. This implies that the supplementary use of MAF might not confer a significant positive impact on healing duration.

A key element of our technique involved a vertical division of almost half the thickness of the IAS, extending to the apex of the fissure. This strategic incision likely contributed to a postoperative reduction in resting anal pressure, ultimately advancing improved anal blood flow and facilitating fissure healing. Precise execution was necessary in achieving uniform depth during IAS division. Notably, while intraoperative endoanal ultrasound was employed in a previous study to guide this process[15], it is important to recognize that ultrasound examination has not yet become the standard of sphincter evaluation in fissure surgery.

It is not certain, however, how far the IAS should be divided vertically. Dividing one third thickness of the IAS vertically can be enough to achieve satisfactory results or dividing two thirds thickness of the IAS may deteriorate continence. Nevertheless, it may not be easy to control the extent of division, because the thickness of the IAS under the fissure was between 1-3 mm[15]. The subcutaneous external sphincter was sutured to the mobilized anorectal mucosa in the MAF technique, which may have caused trauma to the muscle and postoperative decrease in squeeze anal pressure.

The suitability of the VNMS technique depends on patient characteristics, with caution advised for those with hypotonic IAS or a history of previous anal surgery or trauma due to obstetric complications or fistula management, as these factors heighten the risk of postoperative anal incontinence. In such cases, fissurectomy with anal advancement flap remains the recommended course of action[23].

Addressing fissures accompanied by fistulas raises intriguing prospects. In our study, concurrent fistulas were managed through fistulotomy, along with vertical non-full-thickness division of the remaining IAS over the fissure in 12 patients. This approach could potentially reduce the incidence of non-healing fissures. However, the optimal treatment standard for fissure-associated fistulas remains undetermined. Recent research by Adams et al. highlights that a considerable proportion of patients (37%) did not experience healing following fistulotomy in fissure-associated fistulas[24].

It is important to acknowledge certain limitations of our study, including its modest sample size, the absence of a postoperative pain score evaluation, and a median follow-up duration of 27 months, which may be considered relatively short.

In conclusion, the combination of fissurectomy with VNMS and MAF, while necessitating meticulous control over IAS division, emerged as a safe and effective technique. Its capacity to preserve anal continence and avoid “key-hole” deformities underscores its clinical value. Particularly, this technique proved beneficial in cases where midline anal fissures were compounded by fistula formation. Further investigations are warranted to confirm these findings and ascertain their applicability across diverse patient populations.

Conflicts of Interest

There are no conflicts of interest.

Author Contributions

Akira Tsunoda: He contributed to the study conception and design. He performed material preparation, data collection and analysis. He wrote the first draft of the manuscript. He approved the final manuscript.

Hiroshi Kusanagi: He contributed to the study conception and design. He commented on previous versions of the manuscript and read and approved the final manuscript.

Approval by Institutional Review Board (IRB)

Institutional review board: Ethical Committee of Kameda Medical Center

Review board approval number: 22-049-230707