Surgery for Anal Fissure

Updated: Sep 01, 2016
  • Author: Vassiliki Liana Tsikitis, MD, MCR, FACS, FASCRS; Chief Editor: Kurt E Roberts, MD  more...
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An anal fissure is a tear of the squamous epithelium that usually extends from the dentate line to the anal verge. In 90% of cases, the fissure manifests as a painful linear ulcer lying in the posterior midline of the anal canal. The fissure may occur in other areas as well, such as the anterior midline (more commonly in female patients). Patients describe the pain of anal fissures as "passing broken glass" and a burning pain that can remain for several hours after defecation. [1]  Many patients report a lower quality of life because of the pain. [2]

The exact cause of anal fissures is currently unknown. Historically, an anal fissure was thought to be a result of mechanical trauma caused by a hard stool tearing the anoderm as it was passed. [3]  In addition, anal fissures have been associated with increased anal tone for many years. [4]

A proposed mechanism for increased anal tone in a study by Lund showed reduced nitric oxide synthase and, therefore, decreased nitric oxide synthesis in the internal sphincters of patients with anal fissures when compared to control subjects. [5]  Nitric oxide has been known to facilitate smooth muscle relaxation of the internal anal sphincter. [6]

Schouten et al proposed that anal fissures were ischemic ulcers and found that patients with anal fissures had significantly higher resting anal sphincter tone and decreased anodermal blood flow when compared to healthy volunteers. [7]  Other studies have confirmed that blood supply to the posterior midline of the anodermis is relatively poor when compared to that of the other quadrants. [8, 9]

This combination of increased tone and poor blood supply likely contribute to the relative ischemia of the posterior midline of the anoderm; not all patients with anal fissures, however, have anal sphincter hypertrophy or insufficient blood supply to the anoderm.

Treatment of anal fissures is divided into two groups: nonsurgical and surgical. Nonsurgical treatment is considered first-line therapy and includes such modalities as high-fiber diets, stool softeners, warm sitz baths, topical analgesics/anesthetics, and chemical sphincterotomy.

When nonsurgical methods fail to heal the anal fissures or relieve symptoms, however, surgical treatment may be necessary. The surgical treatment options are lateral internal sphincterotomy, fissurectomy, and V-Y advancement flap. Fissurectomy is still used by some surgeons; however, the authors do not recommend fissurectomy, because patients may end up with keyhole deformities. Lateral internal sphincterotomy is the current procedure of choice for surgical treatment of chronic anal fissures. [10]  



Surgical indications include the following:

  • Chronic anal fissures
  • Midline fissures complicated by underlying fistula
  • Fissures associated with increased sphincter tone

Performance of lateral internal sphincterotomy is indicated in the presence of persistent pain, bleeding, and lack of response to medical management. [11, 12]



Fissures associated with decreased sphincter tone are a contraindication for surgical treatment.


Technical Considerations


The anal canal is the most terminal part of the lower gastrointestinal (GI) tract or large intestine. It lies between the anal verge (anal orifice or anus) in the perineum below and the rectum above. The perianal skin is keratinized, stratified squamous epithelium with skin appendages (eg, hair, sweat glands, sebaceous glands, and somatic nerve endings that are sensitive to pain).

The (anatomic) anal canal skin (anoderm) is also keratinized, stratified squamous epithelium and has somatic nerve endings (sensitive to pain), but without skin appendages. The (surgical) anal canal mucosa is cuboidal in the transition zone and columnar above it; it is insensitive to pain. The rectal mucosa above the anorectal ring is lined by pinkish red, insensitive columnar epithelium. For more information about the relevant anatomy, see Anal Canal Anatomy.



More than 90% of fissures heal after lateral internal sphincterotomy. The incidence of recurrence is lower with this procedure than with other available options, including fissurectomy and botulinum injection. Insufficient internal anal sphincterotomy is the most common reason for a nonhealing fissure after treatment.