Up to 70% of chronic anal fissures will heal by conservative therapy alone. If patients have a history of chronic constipation, treatment should include a bulk laxative, such as methylcellulose or psyllium hydrophilic mucilloid, with a mild laxative, such as bisacodyl or docusate sodium. Patients should be told to avoid straining and be instructed in basic anal hygiene.

Application of local nonsteroidal preparations to control pain may be helpful. Local anesthetic agents may be effective, particularly for acute anal fissure. Steroid preparations may be used to reduce inflammation. A wide variety of commercially available ointments and suppositories exist, which consist of local anesthetic and steroid preparations. The cumulative relapse rate after these forms of medical treatment for chronic anal fissure is, 50% at 12 months.

No patient in the United Kingdom today is treated by sphincterotomy for anal fissure unless at least first line, and in some cases, second-line treatment is used because of the fear of bowel incontinence with sphincterotomy.

The most widely used first-line therapy is with nitric oxide donors, usually glyceryl trinitrate cream, but other formulations of topical nitrates give identical results. The cream is applied, where possible, over the fissure after defecation and at night initially, increasing the applications to four times a day if symptoms do not rapidly improve. The principle complication is headache, occurring in 30% to 40%, but if treatment can be tolerated, there is tachyphylaxis in most people such that the headaches do not persist for more than 5 to 6 days. Nitric oxide donors are not tolerated in 20% to 30% because of persistent headache. If patients are able to persist with therapy for 4 weeks, there is complete alleviation of anal pain in 60% to 70%, but in 10% to 20% there may be a relapse of the anal fissure during the next 3 months. Thus, healing is achieved in 45% to 60% of patients in 3 months. For those who relapse a repeat treatment course achieves healing in a further 20% to 30%, overall healing is 60% to 80%.

If patients have a persistent anal fissure and symptoms or cannot tolerate nitric oxide donors the alternative first-line therapy is the use of diltiazem, a calcium channel blocker. Diltiazem cream is used topically over the fissure twice daily initially but up to four applications a day if needed. The preparation is more expensive, but there are virtually no side effects. The outcome in terms of resolution of pain is comparable to those achieved with topical nitrates; pain free at 4 weeks 60% to 70%, with healing at 3 months of 40% to 60%. For those who relapse a repeat course achieves healing in 20% to 30%, overall healing is 60% to 80%.

Patients with anal fissure can be treated surgically during an office visit or in an outpatient surgical unit, but an operation should not be advised until specific first- or second-line treatment has been vigorously pursued. The purpose of surgical treatment is to reduce excessive activity in the internal anal sphincter. In the past this was attempted by anal dilatation, but now only sphincterotomy is used and only after very thorough counseling about the risks of impaired continence.

Anal dilation results in disruption of the fibers of the internal and external anal sphincters. Unfortunately, anal dilatation is associated with a variable risk of bowel incontinence depending on risk factors, but incontinence to flatus is common and may be permanent. For this reason, anal dilatation is no longer advised for the treatment of anal fissure and will, therefore, not be described.

The alternative is internal anal sphincterotomy, which results in division of a part of the internal sphincter, but leaves the external sphincter intact. Sphincterotomy may be performed as a subcutaneous, blind technique or may be performed as an open operation. All patients having sphincterotomy must be warned that there is a risk of temporary or even permanent bowel incontinence following treatment. Preoperative bowel preparation with a disposable enema is usually advised. Postoperatively, the patient should be prescribed adequate analgesics and local anesthetic creams, as well as a mild laxative to avoid postoperative constipation. Patients should be warned that there is a 3% risk of postoperative bleeding, and that local pain may continue for 2 to 3 weeks. Flatus incontinence and soiling is usually transient, lasting only 2 to 3 months, but may occur in 20% to 40% of patients. Long-standing incontinence and soiling may complicate internal sphincterotomy and is not confined to patients in whom a part of the external sphincter has been
inadvertently divided. It can occur when the internal anal sphincter alone has been divided.

This procedure may be performed with local or general anesthesia. The intersphincteric groove is identified. Twenty milliliters of a local anesthetic with a weak adrenaline solution is infiltrated in the submucosal and the intersphincteric planes. A fine cataract blade is inserted in the intersphincteric groove with the blade lying parallel to the circular fibers of the internal sphincter. The cataract blade is then rotated, so that the blade faces the lumen of the anal canal. With the surgeon’s index finger in the anal canal, the cataract blade is advanced toward the index finger so as to divide the internal sphincter, but not the anal mucosa (Fig. 1). A small tampon is placed in the anal canal to prevent hematoma.

This is the author’s preferred surgical procedure. The patient may be placed in the prone jackknife or the lithotomy position, depending on the surgeon’s preference. The lateral aspects of the submucosal and intersphincteric planes are infiltrated with a local anesthetic and a weak adrenaline solution. An anal speculum is inserted to expose the lateral aspect of the anal canal. A circumanal incision is made just inside the anal canal and below the dentate line for a length of approximately 1.0 to 1.5 cm. Scissors are used to develop the submucosal plane so that the anal mucosa can be lifted from the internal sphincter and to develop the intersphincteric plane so that there can be no damage to the external sphincter. Once the lower fibers of the internal sphincter have been clearly separated from other structures, internal sphincterotomy consists of dividing the internal sphincter with scissors for a length of <2 cm (Fig. 2). The results of the closed and open sphincterotomy are comparable. Complete relief of pain and healing of the fissure is recorded in 70% to 90% of patients. It is hardly ever necessary to contemplate a second sphincterotomy for patients with persistent symptoms and in any event this would not be advised on account of the very high risk of permanent incontinence with a second sphincterotomy.

We never advocate posterior sphincterotomy or excision of the anal fissure, sometimes termed fissurectomy, because these operations may be complicated by a gutter deformity in the anal canal and thus result in soiling and impaired continence.

Conservative treatment is never advised for treatment of anorectal sepsis. The practice of prescribing antimicrobial agents in the hope of resolving infection around the anal canal should be discouraged. Antibiotic therapy simply delays adequate surgical drainage. Delay in drainage results in chronic infection and destruction of tissue, particularly if there is synergistic gangrene and necrotizing fasciitis. Delay is often complicated by extensive fibrosis and long-term impairment of function, with incontinence and stricture.

A small perianal abscess is incised using a cruciate or saucer-shaped incision so that pus can be adequately drained. A drainage tube is not inserted. The procedure may be performed in the physician’s office under caudal or general anesthesia (Fig. 6).

A cruciate incision is made to the site of maximum swelling, pus is allowed to drain, and a finger is gently inserted into the ischiorectal fossa to break down any loculi. It is essential to check that there has been no posterior circumferential spread to the opposite side. A drain is not usually left in situ unless the ischiorectal abscess is bilateral or chronic. These operations are much better performed with the patient under general anesthesia. Great care must be taken not to damage the levator plate, which will convert an ischiorectal abscess into ones with a supralevator extension (Fig. 7).

These abscesses are difficult to identify and to localize, and examination with the patient anesthetized is essential. A small incision is made transversely just inside the anal canal and below the dentate line. The intersphincteric space is identified and, with
scissor dissection, the plane between the internal and external sphincters is exposed. If the intersphincteric abscess is well localized, the internal sphincter is divided and the abscess is drained. A small mushroom catheter is left in situ and sutured into position. Failure to insert a mushroom catheter results in contraction of the sphincter muscles because of postoperative pain and impaired drainage, causing recurrent sepsis.

Posterior supralevator abscesses are drained in the manner described for drainage of intersphincteric abscess. The intersphincteric plane is opened posteriorly. It is exposed inside and beyond the puborectalis sling so that the supralevator abscess in the postanal space can be adequately drained. It is essential to suture a mushroom catheter into position. Failure to do so results in recurrent sepsis because of contraction of the puborectalis and sphincters.

Anterior supralevator abscesses are also drained with the patient under general anesthesia using the intersphincteric plane through a transverse anal incision anteriorly. Anterior supralevator abscesses tend to be much more superficial. Again, it is essential to leave a mushroom catheter in situ. Failure to do so results in a high incidence of recurrent sepsis (Fig. 8).

With the patient anesthetized, the abscesses are drained using an anal speculum. Drainage involves opening the mucosa above the swelling so that pus can be discharged. It is often wise to combine the operation with internal sphincterotomy to reduce anal spasm postoperatively to facilitate efficient drainage, which might otherwise lead to a high incidence of persistent sepsis.

The principle of fistulotomy is the identification of the fistula track so that the track can be laid open. Clearly, this method of treatment is inappropriate for patients with extrasphincteric and suprasphincteric fistulae, because the fistula track lies outside the sphincter mechanisms, and any lay-open procedure divides the striated sphincter complex and renders the patient incontinent, usually from a rigid gutter causing soiling. Fistulotomy is thus appropriate only for simple intersphincteric fistulae and low transsphincteric fistulae.

The first and most important maneuver is the demonstration of the primary fistula track. Probing is thus used to define the course of the track and should also identify high blind tracks. If the external opening is located obliquely from the internal opening, there will be some element of circumferential involvement. The course of simple fistulae usually obeys the Goodsall’s rule (Fig. 10). Thus, an external opening lying posterior to the horizontal plane is likely to open into the anal canal at the midline posteriorly, whereas an external opening lying anterior to the horizontal line is more likely to run directly into the anal canal. A malleable fistula probe is gently passed through the fistula track. By use of diathermy, the perianal skin and anal epithelium are divided. The internal sphincter, if involved, is identified and divided. If there is striated muscle superficial to the fistula track, this may be divided provided it consists of only a few fibers. However, if a substantial amount of striated muscle is encountered superficial to the fistula track, division of the muscle is not advisable and a seton is inserted. If a high blind track is found, the track should be loosely curetted and adequately drained through the fistulotomy incision. Provided the fistula track can be safely laid open, any bleeding from the edges should be secured by cautery and gauze dressing applied.

Patients may have more than a single external opening. Multiple anterior openings usually have separate internal openings, which should be dealt with in the same manner by defining all fistula tracks and opening them, provided that this does not involve division of a large amount of striated muscle (Fig. 11). For multiple posterior anal fistulae, the tracks usually open at the same site in the midline posteriorly. Furthermore, under these circumstances, there may be a small supralevator collection in the postanal space. Again, each fistula track is opened, provided that
this does not involve the division of a large amount of striated muscle. The internal opening is then further explored in the intersphincteric plane to ensure that there is no supralevator component. Any redundant skin is excised, and an antiseptic dressing is applied.

The principle of seton fistulotomy is that any striated muscle lying superficial to the fistula track is encircled by a length of soft rubber or latex tubing, or by using a Prolene or silk tie. The seton is tied loosely and left in situ. Over the following weeks, the striated muscle is slowly divided by the presence of the seton. However, because the process of striated muscle division is relatively slow, the muscle does not therefore spring apart, leaving a defect (gutter), but heals behind the process of division. Consequently, fibrous tissue is laid down in the bed of the fistula as it is slowly divided. This process avoids the gutter deformity, which is usually associated with soiling and minimizes the risks of impaired continence. The problem with this technique is that treatment may take a number of weeks and follow-up is essential. On the other hand, preservation of continence is much better than with fistulotomy, especially for mid or high transsphincteric fistula.

The fistula track is identified by using a probe, as described in the previous section. The perianal skin and the skin of the anal canal are divided. The internal sphincter is also divided, but the striated muscle lying superficial to the fistula track is preserved. Thus, a substantial amount of the fistula is laid open. A vascular rubber sling (sloop) is threaded through the eye of the fistula probe and is delivered around the striated muscle as a seton, but other materials may be used (e.g., latex and Teflon). The seton is tied with multiple knots, and the end is sutured beyond the last knot so that it cannot become untied with patient movement during follow-up (Fig. 12). Usually, the patient can be discharged on the same day. Arrangements for follow-up should be made.

At the first follow-up, the seton usually remains in situ but has already partially divided the striated muscle superficial to the fistula track. A simple method of tightening the seton is by the application of rubber bands beyond the first knot. Commonly, five or six bands should be applied to ensure that the seton snuggly surrounds the residual striated muscle. Alternatively, the seton is replaced and retied. A second follow-up in 1 week should then be scheduled. At the second visit, the seton has usually completely divided the striated muscle and has fallen out. If, on the other hand, it has not fallen out, the seton is replaced and follow-up continues until the track has been divided. Thus, the fistula track is slowly divided during a period of 1 to 6 weeks. The technique is remarkably successful at preserving sphincter function and avoiding the development of a gutter deformity. Careful follow-up is essential to detect recurrent fistula. Careful attention to the wound is also essential to ensure that it does not become infected, and that there is no bridging over the fistulotomy site during healing.

Although anorectal advancement with excision of the track should preserve continence and avoid soiling, despite spectacular results reported by some, in this author’s experience, sepsis and recurrent fistula are common. In future, the anal plug may replace this technique.

The first part of the operation involves fistulectomy, that is, excision of the fistula track. This can be technically difficult and involves careful dissection using a fine scalpel or diathermy point around the fistula track through to its internal opening. Side tracks must be similarly excised. In complex fistulae, three or four separate fistula tracks will need to be cored out. The defect in the external sphincter may require closure, and some form of drainage procedure is usually needed. The next step is to close the internal opening, usually with an anorectal advancement flap.

The anorectal advancement flap is simply a way of closing the internal opening of the excised transsphincteric fistula. A wide-based curvilinear flap, consisting of mucosa, submucosa, and rectal wall is advanced from above so as to close the internal component of the fistula without tension, while draining any coexisting sepsis. The technique is fully described and illustrated later in the section on “Rectovaginal Fistula.” However, in anorectal fistula, unlike rectovaginal fistula, there is an external perineal orifice that should be thoroughly drained (Fig. 13).

Extrasphincteric and suprasphincteric fistulae may be treated by total fistulotomy (if setons are not used) while ensuring that the divided and striated muscle is marked so that it can be identified at a later date. Once all of the infection has been cleared, a standard sphincter repair is then performed. The alternative is to perform the reconstruction at the time of the primary lay-open procedure. The problem with sphincter repair under these circumstances is that the primary sphincter repair may break down because of coexisting sepsis. We therefore do not advise the technique in the majority of cases and believe that it has been superseded by fistulectomy and advancement flap closure or the anal plug.