Lateral Internal Sphincterotomy
Position the patient as described (see Patient Preparation). Prepare the surgical field with povidone-iodine or chlorhexidine solution. Drape the field so that the visual field includes the anus. Administer local anesthetic as described above. Inspect the anoderm and anus using an anoscope.
Insert a Pratt bivalve speculum to evaluate the anal pathology. Rotate the Pratt bivalve speculum to the right or left lateral position.
Make a linear incision with a scalpel from the dentate line to just beyond the anal verge. Carry out the dissection until the internal sphincter and a few fibers of the external sphincter are exposed (see the image below).
Achieve hemostasis with electrocautery. Under direct vision, divide the full thickness of the internal sphincter from the level of the dentate line distally (see the image below). Littlejohn and Newstead reported good results in a retrospective study with tailored sphincterotomy—that is, division of the internal anal sphincter for the length of the fissure, rather than the dentate line. The authors recommend tailored sphincterotomy. [14]
Close the incision with a 3-0 chromic catgut suture in a running fashion (see the image below). If preferred, the incision may be left open.
Another option is to perform a closed lateral internal sphincterotomy, in which a “blind” lateral subcutaneous internal anal sphincterotomy is performed with a No. 11 blade scalpel after the intersphincteric groove has been located via manual palpation (see the image below). Studies have found no evidence of a significant difference in results between the open and closed techniques; however, the closed technique requires considerable knowledge of anorectal anatomy and should be reserved for surgeons with advanced colorectal training.
Fissurectomy
In contrast, simple fissurectomy involves excision of the scarred superficial skin around the anal fissure and excision of the sentinel pile, if one is present. The surgical wound can be left open or closed primarily. [12] There are reports that fissurectomy with combination of botulinum injection has a 93% healing rate, with temporary incontinence rate of approximately 7%. [15]
Overall, the authors discourage fissurectomy in combination with lateral internal sphincterotomy, on the grounds it may lead to higher rates of incontinence. For chronic anal fissue refractory to medical management and chemodenervation, lateral internal sphincterotomy is the recommended treatment.
Chemical Sphincterotomy
There is a great deal of controversy regarding the use of botulinum toxin for the treatment of anal fissures. Injection of this toxin is typically used for chronic anal fissures that have failed to improve with medical management. Additionally, there may be a role for it in the management of recurrent anal fissure following lateral internal sphincterotomy. [16]
Published techniques involve injection dosages that range from 10 to 100 units. Healing rates have varied in the literature, from 67.5% to over 90%, according to a 2012 Cochrane review. [17] Recurrence rates after botulinum toxin treatment are high, and range from 40% to over 50% at 1 year. Incontinence and flatus are common after the procedure; however, they spontaneously resolve in all patients. [18] In comparison with other topical treatments (eg, nitroglycerin), botulinum yields similar results with a lower incidence of adverse events. [3]
The authors typically use 100 units of onabotulinumtoxinA, injecting 40 units in both the right and the left intersphincteric groove, along with 10 units in both the anterior and the posterior anal canal. Patients are continued on stool softeners and a topical calcium-channel blocker for 8 weeks. Success rates are in the 90th percentile; failure of this treatment has been noted, especially in patients with longstanding chronic anal fissures.
Complications
Possible complications of anal fissure surgery include the following:
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Bleeding
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Infection
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Fissure recurrence
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Hemorrhoidal tissue prolapse
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Initial dissection.
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Division of internal sphincter.
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Closure of incision.
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Closed lateral internal sphincterotomy.
