Anal fissure: Surgical management

INTRODUCTION — An anal fissure is a tear or ulceration in the lining of the anal canal below the mucocutaneous junction (dentate line) (figure 1). Most commonly caused by local trauma, anal fissures cause pain during defecation that persists for one to two hours. Persistence of an anal fissure is typically associated with anal spasm or high anal pressure. Medical management is typically used as the initial treatment for an anal fissure [1,2]. Surgery is reserved for patients who fail medical therapy [3-6].

Surgical modalities of anal fissure treatment, including lateral internal sphincterotomy and botulinum toxin injection, are discussed in this topic. The clinical presentation, diagnosis, prevention, and medical management of anal fissure are discussed elsewhere. (See "Anal fissure: Clinical manifestations, diagnosis, prevention" and "Anal fissure: Medical management".)

TYPICAL ANAL FISSURE REFRACTORY TO MEDICAL THERAPY — Medical treatment heals a typical anal fissure in most patients. (See "Anal fissure: Medical management", section on 'Initial management of typical fissures'.)

Surgical treatment may be offered to patients whose fissure does not heal with medical therapy. Patients who are willing to undergo surgical treatment are further triaged based upon their risk of fecal incontinence. Women who have had multiple vaginal deliveries and older patients may have a weak anal sphincter complex, which puts them at a high risk of developing fecal incontinence after surgical treatment of anal fissure. Such patients should undergo one of the procedures that do not require division of the anal sphincter muscle (eg, botulinum toxin injection, fissurectomy, or anal advancement flap). Other patients who are not at risk of developing fecal incontinence may undergo lateral internal sphincterotomy, which is considered the most effective treatment for anal fissure (algorithm 1) [7-9].

Patients with low risk of incontinence: Sphincterotomy — A lateral internal sphincterotomy provides prompt symptomatic relief and heals anal fissures in over 95 percent of patients within three weeks [10-18]. In patients who are at a low risk of developing fecal incontinence, the lateral internal sphincterotomy is the gold standard for the operative management of an anal fissure secondary to hypertonicity or hypertrophy of the internal anal sphincter [7-9]. As the gold standard, lateral internal sphincterotomy has been compared with all other therapies for anal fissure, including topical nitroglycerin [3,19], botulinum toxin A injection [6,20], and oral nifedipine [21]. Lateral internal sphincterotomy remains superior in its efficacy to all other therapies, according to a 2017 systematic review [22].

A Lord's, or four-finger, dilatation in the operating room had been previously used for the treatment of anal fissures before lateral sphincterotomy [23]. Although this treatment can improve the spasm in the internal anal sphincter, it is associated with a high incidence of sphincter tears and fecal incontinence and therefore has been abandoned [24,25]. Neuromodulation has also been studied as a sphincter-sparing treatment for anal fissure [26]; however, experience is limited with this technique, and it has not been compared directly with other approaches. A midline posterior sphincterotomy was found to be inferior to lateral internal sphincterotomy and is rarely performed because it can result in a "keyhole deformity" [24]. However, for fissures associated with anal stenosis, a posterior sphincterotomy combined with a VY advancement flap is appropriate [27]. (See 'Anal advancement flap' below.)

Preoperative preparation — Intravenous antibiotics are not generally required for patients undergoing a sphincterotomy. (See "Antimicrobial prophylaxis for prevention of surgical site infection following gastrointestinal procedures in adults", section on 'Colorectal procedures'.)

Type of anesthesia — A lateral internal sphincterotomy can be performed in the surgeon's office using a local anesthetic, or in the operating room under regional or general anesthesia. The choice of anesthesia is determined by both patient and surgeon preference, although a retrospective study of 298 patients reported a higher rate of fissure recurrence after a lateral internal sphincterotomy performed under local, as opposed to general, anesthesia (9 of 20 versus 23 of 271) [28].

Patient positioning — Positioning options for lateral internal sphincterotomy include the prone jackknife, lithotomy, and lateral decubitus positions. The location of the fissure does not influence the choice of patient positioning. We prefer to place the patient in a prone jackknife position. Patients with obesity are typically placed in the lateral decubitus position since they frequently do not tolerate the prone jackknife or lithotomy position.

Operative technique — After the patient is properly positioned, gentle anal dilation is performed to allow admittance of a medium (0.75 to 1 inch [1.90 to 2.54 cm]) rectal retractor. Anoscopy is performed using the rectal retractor. The internal sphincter muscle is then divided at a lateral position.

Incision — The procedure can be performed in either an open or a closed manner at the surgeon's discretion.

●In the open technique, the surgeon incises the anoderm to expose the internal sphincter muscle and divides it under direct vision. Complete division of the internal sphincter muscle fibers is important since an incompletely divided internal sphincter has been associated with a marked increase in fissure recurrence. (See 'Incomplete sphincterotomy' below.)

●In the closed technique, the surgeon inserts a blade either directly under the anoderm or into the intersphincteric groove and divides the internal sphincter without widely incising the anal mucosa.

A meta-analysis of five randomized trials with 299 patients found no significant difference between the two techniques in terms of the rate of healing or incontinence [24]. In the largest trial of 79 patients, the rate of fissure healing was 96 percent at six weeks, and new incontinence was diagnosed in five patients (6.8 percent) at 52 weeks for open and closed procedures combined [14].

Location — Regardless of the method chosen, most surgeons perform a lateral internal sphincterotomy. We typically perform the sphincterotomy on the right side between the anterior and posterior hemorrhoidal columns to avoid confusion if a repeat procedure is required. A posterior sphincterotomy is rarely performed [13].

Extent — The extent of the sphincterotomy remains controversial. We recommend performing a tailored or partial fissure apex sphincterotomy rather than the conventional longer sphincterotomy as described here [29]:

●The conventional longer sphincterotomy divides the internal anal sphincter muscle to the level of or just proximal to the dentate line [30,31].

●The tailored or partial sphincterotomy divides the internal anal sphincter only to the level of the apex of the fissure and therefore is also referred to as the "fissure apex sphincterotomy." Compared with the longer sphincterotomy, this approach preserves more sphincteric muscle fibers [10,32].

Three randomized trials of conventional versus tailored sphincterotomy showed statistically superior fissure healing rates in the conventional arm, but two trials reported worse fecal continence scores in the conventional arm [10,33], whereas one did not [21].

The actual fissure may or may not be excised at the time of a lateral sphincterotomy at the surgeon's discretion, but a biopsy should be performed if the fissure has an atypical appearance. (See 'Atypical anal fissure' below.)

Postoperative care — Infiltration of the operative site with a local anesthetic before and/or after the sphincterotomy will provide postoperative pain relief [34,35]. Multimodal pain management with gabapentin 300 mg twice daily and naproxen 500 mg twice daily can be used as primary postoperative analgesia. Rarely, oral opioids will be needed for breakthrough pain. The use of multimodal pain management improves analgesia, results in lower opioid usage, and lowers the rate of urinary retention [36,37]. (See "Enhanced recovery after colorectal surgery", section on 'Pain management'.)

Since a bladder catheter is not typically used, limiting perioperative fluid administration to less than one liter lowers the incidence of postoperative urinary retention [38-40]. Postoperative instructions include recommendations for sitz baths for comfort, adequate intake of fluid and fiber to avoid constipation, and limited activity for a few days. These instructions are primarily derived from clinical experience, rather than specific data. With appropriate postoperative instruction, a lateral sphincterotomy can be performed with a high degree of patient satisfaction [41].

Risk of fecal incontinence — A major concern with surgery for anal fissures is the risk of fecal incontinence [10,14,24]. Fecal incontinence can be characterized as either minor (defined as inadvertent escape of flatus or partial soiling of undergarments with liquid stool) or major (involuntary excretion of feces). (See "Fecal incontinence in adults: Etiology and evaluation".)

Lateral internal sphincterotomy can cause long-term (≥2 years) incontinence of both flatus and stool. In a meta-analysis of 22 retrospective and prospective studies that included 4512 patients who were followed for ≥2 years after a lateral internal sphincterotomy for chronic anal fissure, the overall continence disturbance rate was 14 percent, which included flatus incontinence in 9 percent, soilage/seepage in 6 percent, accidental defecation in 0.91 percent, incontinence to liquid stool in 0.67 percent, and incontinence to solid stool in 0.83 percent of patients [42].

Others estimate that 30 to 45 percent of patients experience minor fecal incontinence immediately following lateral internal sphincterotomy, with 6 to 30 percent of patients having persistent symptoms long-term [11,28]. By contrast, only approximately 2 percent of the general population suffers from fecal incontinence [43]. The risk is increased in women, particularly those who have had previous vaginal deliveries. In one study of 487 patients, women were significantly more likely to develop fecal incontinence after a sphincterotomy than men (53 versus 33 percent) [17].

Patients with high risk of incontinence — For patients who are at a high risk of developing fecal incontinence (eg, multiparous women or older patients), options for surgical management of anal fissure include botulinum toxin A injection, V-Y advancement flap, and subcutaneous fissurectomy. These alternatives to lateral sphincterotomy do not require the internal sphincter muscle to be divided and thereby reduce the risk of fecal incontinence.

Botulinum toxin injection — Botulinum toxin is a potent inhibitor of the release of acetylcholine from nerve endings and has been used successfully for decades to treat certain spastic disorders of skeletal muscle such as blepharospasm and torticollis. It has also been used to treat spastic disorders of the gastrointestinal tract such as achalasia and anal fissure.

Injection of botulinum toxin into the anal sphincter can help relax the hypertonic anal sphincter muscle and, in turn, improve healing of chronic anal fissures. A commercially prepared form of botulinum toxin type A (eg, Botox, Dysport) is typically given as injections around the anal canal. Doses (ranging from 10 to 100 units) vary depending upon the specific brand and preparation of the botulinum toxin that is used.

In one protocol, 10 units of Botox (0.2 mL of 50 units per mL) each are injected into the internal anal sphincter on either side of the anal fissure with a 27 gauge needle [44]. In a trial of 30 patients with chronic anal fissures, botulinum toxin injection using this protocol resulted in significantly more fissure healing than saline control at one (8 of 15 versus 2 of 15) and two months (11 of 15 versus 2 of 15) [44]. The four patients who had persistent fissures two months after botulinum toxin injection were retreated, and all healed by two months thereafter. One patient developed temporary flatus incontinence after Botox injection. No relapse occurred during an average follow-up of 16 months.

Other studies with longer follow-ups, however, found recurrence rates of 40 to 50 percent after botulinum toxin treatment of anal fissures [45,46]. Patients who relapse may be retreated with botulinum toxin with good results [47]. Temporary fecal incontinence after botulinum toxin therapy has been reported to occur at a rate of approximately 7 percent, which compares favorably with the 30 to 45 percent of patients who experience minor fecal incontinence following lateral sphincterotomy [47,48].

In a Cochrane meta-analysis, botulinum toxin injection was found to be equally efficacious in treating chronic anal fissures as topical nitroglycerin [49]. However, because botulinum toxin is more invasive and is associated with a greater risk of mild incontinence, we generally reserve it for patients who have not responded to first-line medical therapy with one of the topical vasodilators. (See "Anal fissure: Medical management", section on 'Initial management of typical fissures'.)

Botulinum toxin treatment for anal fissure has been performed safely in patients who developed anal fissures while actively receiving chemotherapy [50].

Fissurectomy — A fissurectomy, or excision of the anal fissure, is also an effective treatment of chronic anal fissure that has a low recurrence rate and a low risk of fecal incontinence. In a study of 53 patients whose chronic anal fissures were successfully treated with fissurectomy, only five patients (11 percent) recurred with a five-year follow-up [51]. Fissurectomy did not affect the rate of fecal incontinence.

Fissurectomy has also been performed in conjunction with botulinum toxin injection to treat anal fissures. In two studies, such combination treatment resulted in fissure healing rates of 67 to 83 percent, minor incontinence rates of 3 to 7 percent, and fissure recurrence rates of 0 to 17 percent [52,53].

Anal advancement flap — An anal advancement flap, such as the endoanal V-Y advancement flap (figure 2), does not divide the internal sphincter and is not associated with any increased risk of fecal incontinence [54,55]. It is an alternative to the lateral internal sphincterotomy for patients who are at risk of developing fecal incontinence (eg, older adults, multiparous women, recurrent fissures), especially for those whose fissures are not related to hypertonicity of the sphincter muscle [54,56-60]. A 2018 systematic review with 300 patients found that anal advancement flap was associated with a significantly lower rate of anal incontinence compared with lateral internal sphincterotomy (odds ratio [OR] 0.06, 95% CI 0.01-0.36). There were no statistically significant differences in unhealed fissures (OR 2.21, 95% CI 0.25-19.33) or wound complication rates (OR 1.41, 95% CI 0.50-4.99) between the two treatments [61].

The same V-Y advancement flap that is used to treat anal fissures can be used to treat anal fistulas. Details are discussed elsewhere. (See "Operative management of anorectal fistulas", section on 'Advancement flaps'.)

PERSISTENT OR RECURRENT ANAL FISSURE AFTER SURGERY — Fissures that fail to heal or that recur after lateral internal sphincterotomy have been associated with an incomplete sphincterotomy, sphincter hypertonia, or chronic morphologic changes within the fissure, including fibrosis, a sentinel pile, or rolled edges [62-64]. Patients who have persistent or recurrent anal fissures despite surgery are generally managed conservatively with a high-fiber diet and ample fluid intake [16,62-69]. These conservative measures can heal approximately two-thirds of persistent or recurrent fissures that are unrelated to infection, inflammation, or malignancy [16,17]. The remainder of the patients receive further treatment based upon their symptoms [63,64].

No pain — When a persistent anal fissure bleeds with bowel movements but is not painful, it does not require operative intervention.

Minimal pain — When a fissure does not heal and is minimally painful, a subcutaneous fissurectomy can be performed, especially if the fissure has one of the following chronic morphologic changes (see 'Fissurectomy' above):

●Fibrosis

●A sentinel pile

●Rolled edges

Severe pain — When a persistent or recurrent fissure causes severe rectal pain, anal sonography is indicated to assess the extent of the previous lateral internal sphincterotomy. Further management depends upon the completeness of the initial sphincterotomy [16,54,70,71].

Incomplete sphincterotomy — If the lateral internal sphincterotomy was not complete, a repeat procedure is performed to complete the sphincterotomy to the level of the dentate line. The repeat sphincterotomy can be performed on the same side or, more commonly, on the contralateral side to avoid scar tissues from the first procedure. A subcutaneous fissurectomy can also be added at the surgeon's discretion, based upon the presence or absence of the same chronic morphologic changes listed above.

In a review of 51 patients following a lateral internal sphincterotomy, there was a significantly increased risk of fissure recurrence with an incompletely divided internal sphincter compared with a completely divided sphincter (75 versus 10 percent) [62].

Complete sphincterotomy — If the lateral internal anal sphincter muscle is clearly divided to a point proximal to the dentate line, a surgical fissurectomy can be performed, and an endoanal V-Y advancement flap is used to cover the defect. (See 'Anal advancement flap' above.)

ATYPICAL ANAL FISSURE — The finding of an atypical anal fissure (multiple, off midline, large, or irregular) should alert the surgeon to the possibility of a secondary manifestation of a systemic illness, such as Crohn disease, tuberculosis, HIV infection, adenocarcinoma, metastatic basal cell carcinoma, lymphoma, or leukemia [16,65-68]. The patient evaluation should include a thorough history and physical examination focusing on secondary manifestations of a systemic disease, wound cultures to identify a possible infection, and an examination under anesthesia with biopsies to rule out malignancy [64]. (See "Perianal and perirectal abscess" and "Perianal Crohn disease" and "Evaluation of anorectal symptoms in men who have sex with men" and "Anal squamous intraepithelial lesions: Epidemiology, clinical presentation, diagnosis, screening, prevention, and treatment" and "Anal fissure: Clinical manifestations, diagnosis, prevention".)

Anal fissures related to an underlying systemic illness are best initially treated with aggressive medical management of that illness. As an example, patients with anal fissures due to Crohn proctitis should be referred to a gastroenterologist for optimal management of their Crohn disease. Anal fissures related to Crohn disease are multiple in approximately one-third of patients. These fissures are usually painless. Thus, excessive rectal pain in a patient with Crohn-related anal fissures should raise suspicion for development of a perirectal abscess and prompt an examination under anesthesia and possibly a drainage procedure [69]. Because sphincter preservation is important for patients who often have chronic diarrhea, anal fissures in Crohn patients are typically treated medically rather than surgically. A lateral sphincterotomy is reserved for Crohn patients with minimal active anorectal inflammation who fail all available nonsurgical therapies [64]. (See "Perianal Crohn disease".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Anal fissure".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics". The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Beyond the Basics topics (see "Patient education: Anal fissure (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●General algorithm for managing anal fissures – Medical treatment heals a typical anal fissure in most patients. Surgery is offered to patients who fail medical therapy (algorithm 1). (See "Anal fissure: Medical management" and 'Introduction' above.)

●Typical primary anal fissures – Patients who are willing to undergo surgical treatment are further triaged based upon their risk of fecal incontinence. Women who have had multiple vaginal deliveries and older patients may have a weak anal sphincter complex, which puts them at a high risk of developing fecal incontinence after surgical treatment of anal fissure.

•We suggest performing a lateral internal sphincterotomy in patients with a low risk of developing fecal incontinence (Grade 2C). (See 'Patients with low risk of incontinence: Sphincterotomy' above.)

We recommend performing a tailored or partial sphincterotomy (ie, fissure apex sphincterotomy) rather than a longer sphincterotomy (Grade 1B). The procedure can be performed in an open or closed fashion. (See 'Extent' above.)

•For patients who are at a high risk of developing fecal incontinence (eg, multiparous women or older patients), surgical options include botulinum toxin A injection, V-Y advancement flap, and subcutaneous fissurectomy. These alternatives to lateral internal sphincterotomy do not require the internal sphincter muscle to be divided and thereby reduce the risk of fecal incontinence. (See 'Patients with high risk of incontinence' above.)

●Anal fissures after sphincterotomy – If a persistent or recurrent anal fissure develops after a lateral internal sphincterotomy was performed and causes the patient severe pain, anal ultrasonography is performed to determine the completeness of the prior sphincterotomy. (See 'Persistent or recurrent anal fissure after surgery' above.)

•Patients who have an incomplete sphincterotomy should undergo repeat sphincterotomy on the same or opposite side.

•Patients who have a complete sphincterotomy should undergo a fissurectomy followed by V-Y advancement flap closure.

●Atypical anal fissures – The finding of an atypical anal fissure (multiple, off midline, large, or irregular) should alert the surgeon to the possibility of a secondary manifestation of a systemic illness, such as Crohn disease, tuberculosis, HIV infection, adenocarcinoma, metastatic basal cell carcinoma, lymphoma, or leukemia. Aggressive and optimal medical management of the underlying medical disease should be performed prior to operative management of an atypical anal fissure. (See 'Atypical anal fissure' above.)