Anal Fissure Treatment & Management

Updated: Mar 29, 2023
  • Author: Lisa Susan Poritz, MD; Chief Editor: John Geibel, MD, MSc, DSc, AGAF  more...
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Approach Considerations

Failure of medical therapy to resolve the acute fissure is an indication for surgical intervention. The presence of a symptomatic chronic fissure is also an indication for surgery because few of these heal spontaneously.

The main contraindication to surgery for an anal fissure is impaired fecal continence, a state that could be exacerbated by surgery. This contraindication mostly applies to patients with minor incontinence (occasional seeping).

Patients with gross fecal incontinence (solid material) rarely develop fissures; however, those with irritable bowel syndrome and incontinence to liquid stool can develop fissures if they become constipated. These patients are at the most risk for surgical treatment of an anal fissure, because their typical bowel pattern is loose and harder to control.

The American Society of Colon and Rectal Surgeons (ASCRS) has published clinical practice guidelines on the management of anal fissure. [5] The American College of Gastroenterology (ACG) clinical guideline on the management of benign anorectal disorders includes recommendations for chronic anal fissure. [6] (See Guidelines.)


Medical Therapy

Initial therapy for an anal fissure is medical in nature, and more than 80% of acute anal fissures resolve without further therapy. The goals of treatment are to relieve the constipation and to break the cycle of hard bowel movement, associated pain, and worsening constipation. Softer bowel movements are easier and less painful for the patient to pass.

First-line medical therapy consists of therapy with stool-bulking agents, such as fiber supplementation and stool softeners. Laxatives are used as needed to maintain regular bowel movements. Mineral oil may be added to facilitate passage of stool without as much stretching or abrasion of the anal mucosa, but it is not recommended for indefinite use. Sitz baths after bowel movements and as needed provide significant symptomatic relief because they relieve some of the painful internal sphincter muscle spasm.

Recurrence rates are in the range of 30-70% if the high-fiber diet is abandoned after the fissure is healed. This range can be reduced to 15-20% if patients remain on a high-fiber diet.

Second-line medical therapy consists of intra-anal application of 0.4% nitroglycerin (NTG; also called glycerol trinitrate) ointment directly to the internal sphincter. [7] Nitroglycerin rectal ointment is approved by the US Food and Drug Administration (FDA) for moderate-to-severe pain associated with anal fissures and may be considered when conservative therapies have failed. [8]

Some physicians use NTG ointment as initial therapy in conjunction with fiber and stool softeners, and others prefer to add it to the medical regimen if fiber and stool softeners alone fail to heal the fissure. NTG ointment is thought to relax the internal sphincter and to help relieve some of the pain associated with sphincter spasm; it also is thought to increase blood flow to the anal mucosa.

Unfortunately, many people cannot tolerate the adverse effects of NTG, and as a result, its use is often limited. The main adverse effects are headache and dizziness; therefore, patients should be instructed to use NTG ointment for the first time in the presence of others or directly before bedtime.

Analogous to the use of NTG intra-anal ointment, nifedipine ointment is also available for use in clinical trials. It is thought to have similar efficacy to NTG ointment but with fewer adverse effects.

Botulinum toxin (eg, onabotulinumtoxinA [BOTOX®]) has been used to treat acute and chronic anal fissures. It is injected directly into the internal anal sphincter, in effect performing a chemical sphincterotomy. The effect lasts about 3 months, until nerve endings regenerate. This 3-month period may allow acute fissures (and sometimes chronic fissures) to heal and symptoms to resolve. [9] If botulinum toxin injection provides initial relief of symptoms but there is a recurrence after 3 months, the patient may benefit from surgical sphincterotomy. [10, 11]

In a review of four prospective, randomized, controlled trials that included a total of 279 patients, Shao et al concluded that surgery—specifically, lateral internal sphincterotomy—was more effective than botulinum toxin injection for healing chronic anal fissures. [12] For surgery as compared with toxin injection, there was an absolute benefit increase rate of 23%, with toxin injection associated with a lower fissure healing rate and a higher recurrence rate. However, the incidence of minor anal incontinence was higher with surgery.


Surgical Therapy

Surgical therapy is usually reserved for acute anal fissures that remain symptomatic after 3-4 weeks of medical therapy and for chronic anal fissures.

Preparation for surgery

The administration of two Fleet enemas on the morning of the procedure is sufficient bowel preparation for surgical treatment of an anal fissure. If the fissure is too painful, the enemas may be omitted. No other preoperative preparation is necessary unless the patient has significant comorbidities that require attention.

Procedural details

Sphincter dilatation

This procedure is a controlled anal stretch or dilatation under general anesthetic. It is performed because one of the causative factors for anal fissure is thought to be a tight internal anal sphincter. Stretching the tight sphincter helps correct the underlying abnormality, thus allowing the fissure to heal. The number of fingers used and the amount of time for which the stretch is applied vary among surgeons.

Although the sphincter stretch does provide symptomatic relief from the anal fissure, it is rarely performed today, because of the high complication rate. Impaired continence is observed in 12-27% of patients as a consequence of uncontrolled stretching and subsequent tearing of the internal and external sphincter.

Lateral internal sphincterotomy

Lateral internal sphincterotomy is the current surgical procedure of choice for anal fissure. The procedure can be performed with the patient under general or spinal anesthesia. (Local anesthesia may even be used in the cooperative patient, though it is not always recommended). The purpose of the operation is to cut the hypertrophied internal sphincter, thereby releasing tension and allowing the fissure to heal. [13]

When first described, sphincterotomy was performed in the posterior midline at the site of the fissure, with or without a fissurectomy. [14] However, the incision for the sphincterotomy usually did not heal, for exactly the same reason that the fissure did not heal. Currently, sphincterotomies are normally performed in the lateral quadrants (right or left, depending on the comfort or handedness of the surgeon). In a properly performed lateral internal sphincterotomy, only the internal sphincter is cut; the external sphincter is not cut and must not be injured.

The sphincterotomy can be performed in either an open or a closed manner, as described below.

In a closed sphincterotomy, a No. 11 blade is inserted sideways into the intersphincteric groove laterally. It is then rotated medially and drawn out to cut the internal sphincter. Care is taken not to cut the anal mucosa, because doing so could result in a fistula. After the knife is removed, the anal mucosa overlying the sphincterotomy is palpated, and a gap in the internal sphincter can be felt through it. The sphincterotomy is extended into the anal canal for a distance equal to the length of the anal fissure.

In an open sphincterotomy, a 0.5- to 1-cm incision is made in the intersphincteric plane. The internal sphincter is then looped on a right angle and brought up into the incision. The internal sphincter is then cut under direct visualization. The two ends are allowed to fall back after being cut. A gap can then be palpated in the internal sphincter through the anal mucosa, as in the closed technique. The incision can be closed or left open to heal.

When treating a chronic anal fissure, the surgeon may elect to perform a fissurectomy in conjunction with the lateral sphincterotomy. In such cases, care must be taken not to include a piece of the internal sphincter with the excision. More simply, instead of excising the fissure along with the sphincterotomy and worrying whether it will heal, the surgeon can excise the hypertrophied papillae and the skin tag and leave the fissure to heal on its own.

Sometimes, long-standing chronic fissures do not heal, even with an adequate sphincterotomy, and an advancement flap must be performed to cover the defect in the mucosa. This can be performed either at the time of the sphincterotomy if the surgeon does not think that the fissure will heal or as a second procedure if the fissure does not heal.


Postoperative Care

Sphincterotomy is performed either in an outpatient setting or as an office procedure, and patients return home the same day. Typically, minimal postoperative pain is associated with either the closed or the open technique—usually no more than the fissure caused preoperatively. Pain from the fissure starts to abate almost immediately. The only postoperative restrictions are from the anesthetic, and many patients can return to normal activities the following day.



Complications from surgery for anal fissure include the following:

  • Infection
  • Bleeding
  • Fistula development
  • Incontinence (the most feared complication)

Infection after sphincterotomy is rare and occurs as a small abscess in only 1-2% of patients, despite the inherent uncleanliness of the area. Treatment is drainage of the abscess. Antibiotics are necessary only if significant associated cellulitis occurs or if the patient is immunosuppressed.

Some ecchymosis may occur around the sphincterotomy site, but bleeding that necessitates therapy is extremely rare.

Fewer than 1% of patients develop an anal fistula at the site of the sphincterotomy. This usually results from a breach of the mucosa at the time of the sphincterotomy. The fistula is often low and superficial and should be treated with fistulotomy.

The incidence and definition of incontinence vary dramatically from study to study and among the different procedures. Of patients undergoing the sphincter stretch, 12-27% report problems with continence after the procedure. This is most likely because this is an uncontrolled stretch of the anal sphincter and because both the internal and external sphincters are stretched.

Incontinence rates are much lower with a properly performed internal sphincterotomy than with sphincter stretch, though these rates depend on the definition of incontinence being applied. In most patients, the minor soiling or incontinence to flatulence that may occur in the immediate postoperative period usually resolves without any long-term sequelae.

The recurrence or nonhealing rates for anal fissures after surgical treatment are in the range of 1-6%. Several studies found that as many as 50% of subjects who did not heal had underlying undiagnosed Crohn disease as the etiology for their fissure.


Long-Term Monitoring

Prescribe stool softeners and fiber supplementation after the surgery, and recommend fiber supplementation indefinitely to prevent future problems with constipation. Follow-up care usually consists of a single postoperative visit to ensure that the wound is healing appropriately and that the fissure has resolved.