Introduction
Problem
An anal fissure (see images below) is a painful linear tear or crack in the distal anal canal, which, in the short term, usually involves only the epithelium and, in the long term, involves the full thickness of the anal mucosa.
Acute anal fissure.
Anal fissure.
For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education articles Anal Abscess, Rectal Pain, and Rectal Bleeding.
Frequency
Anal fissures develop with equal frequency in both sexes; they tend to occur in younger and middle-aged persons.
Etiology
The exact etiology of anal fissures is unknown, but the initiating factor is thought to be trauma from the passage of a particularly hard or painful bowel movement. Low-fiber diets, such as those lacking in raw fruits and vegetables, are associated with the development of anal fissures. No occupations are associated with a higher risk for the development of anal fissures. Prior anal surgery is a predisposing factor because scarring from the surgery may cause either stenosis or tethering of the anal canal, which makes it more susceptible to trauma from hard stool.Initial minor tears in the anal mucosa due to a hard bowel movement probably occur often, and, in most people, these heal rapidly without long-term sequelae. In patients with underlying abnormalities of the internal sphincter, these injuries progress to acute and chronic anal fissures. Studies of the internal anal sphincter and of anal canal physiology have been performed with varied results, but at least 1 abnormality is likely present in the internal anal sphincter of many anal fissure patients.
The most commonly observed abnormalities are hypertonicity1 and hypertrophy of the internal anal sphincter, leading to elevated anal canal and sphincter resting pressures. The internal sphincter maintains the resting pressure of the anal canal; anal-rectal manometry can be used to measure this pressure. Most patients with anal fissures have an elevated resting pressure, which returns to normal levels after surgical sphincterotomy.
The posterior anal commissure is the most poorly perfused part of the anal canal. In patients with hypertrophied internal anal sphincters, this delicate blood supply is further compromised, thus rendering the posterior midline of the anal canal relatively ischemic.
This is thought to account for why many fissures do not heal spontaneously and may last for several months. Pain accompanies each bowel movement as this raw area is stretched and the injured mucosa is abraded by the stool. The internal sphincter also begins to spasm when a bowel movement is passed, which has 2 effects. First, the spasm itself is painful; second, the spasm further reduces the blood flow to the posterior midline and the anal fissure, contributing to the poor healing rate.
Pathophysiology
See Etiology.
Presentation
Typically, the symptoms of an anal fissure are relatively specific, and the diagnosis can often be made based on history findings alone. The patient reports severe pain during a bowel movement, with the pain lasting several minutes to hours afterward. The pain recurs with every bowel movement, and the patient commonly becomes afraid or unwilling to have a bowel movement, leading to a cycle of worsening constipation, harder stools, and more anal pain. Approximately 70% of patients note bright red blood on the toilet paper or stool. Occasionally, a few drops may fall in the toilet bowl, but significant bleeding does not usually occur with an anal fissure.
Initially, the fissure is just a tear in the anal mucosa and is defined as an acute anal fissure. If the fissure persists over time, it progresses to a chronic fissure that can be distinguished by its classic features. The fibers of the internal anal sphincter are visible in the base of the chronic fissure, and often, an enlarged anal skin tag is present distal to the fissure and hypertrophied anal papillae are present in the anal canal proximal to the fissure.
Most anal fissures occur in the posterior midline, with the remainder occurring in the anterior midline (99% of men, 90% of women). Two percent of patients have anterior and posterior fissures. Fissures occurring off the midline should raise the possibility of other etiologies (eg, Crohn disease), an infectious etiology (eg, sexually transmitted disease, acquired immunodeficiency syndrome [AIDS]2 ), or cancer.
Indications
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.
Relevant Anatomy
Thorough knowledge of the anatomy of the anal canal is vital for surgical treatment of an anal fissure (see image below).
Anal fissure.
Anal canal
The anal canal has 2 definitions. The first is the functional, or surgical, anal canal, and the second is the anatomic anal canal. The terms are often used interchangeably, even though they do not mean the same thing. The surgical anal canal is approximately 4 cm long and extends from the anal verge or intersphincteric groove, distally, to the anorectal ring, proximally. The anatomic anal canal is only approximately 2 cm long and extends from the anal verge, distally, to the dentate line, proximally.
Anal verge
The anal verge is an anocutaneous line approximately 2 cm distal to the dentate line. The anal verge marks the beginning of the anal canal.
Dentate line
The dentate line is the junction of the ectoderm and endoderm in the anal canal.
Internal anal sphincter
The internal anal sphincter is a smooth muscle that is the most distal extension of the inner circular smooth muscle of the colon and the rectum. It is 2.5-4 cm long and is normally 2-3 mm thick. The internal sphincter is not under voluntary control and is continuously contracted to prevent unplanned loss of stool.
External anal sphincter
The external anal sphincter is striated muscle that forms a circular tube around the anal canal. Proximally, it merges with the puborectalis muscle and the levator ani to form a single complex. Control of the external anal sphincter is voluntary.
Contraindications
The main contraindication to surgery for an anal fissure is impaired fecal continence, because this could be worsened with 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 more difficult to control.
More on Anal Fissure |
 Overview: Anal Fissure |
| Workup: Anal Fissure |
| Treatment: Anal Fissure |
| Follow-up: Anal Fissure |
| Multimedia: Anal Fissure |
| References |
| Further Reading |
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References
Farid M, El Nakeeb A, Youssef M, et al. Idiopathic hypertensive anal canal: a place of internal sphincterotomy. J Gastrointest Surg. Jun 11 2009;[Medline].
Abramowitz L, Benabderrahmane D, Baron G, et al. Systematic evaluation and description of anal pathology in HIV-infected patients during the HAART era. Dis Colon Rectum. Jun 2009;52(6):1130-6. [Medline].
Schiano di Visconte M, Munegato G. Glyceryl trinitrate ointment (0.25%) and anal cryothermal dilators in the treatment of chronic anal fissures. J Gastrointest Surg. Jul 2009;13(7):1283-91. [Medline].
Shao WJ, Li GC, Zhang ZK. Systematic review and meta-analysis of randomized controlled trials comparing botulinum toxin injection with lateral internal sphincterotomy for chronic anal fissure. Int J Colorectal Dis. Mar 6 2009;[Medline].
Mousavi SR, Sharifi M, Mehdikhah Z. A comparison between the results of fissurectomy and lateral internal sphincterotomy in the surgical management of chronic anal fissure. J Gastrointest Surg. Jul 2009;13(7):1279-82. [Medline].
American Society of Colon and Rectal Surgeons, Standards Task Force. Practice Parameters for Ambulatory Anorectal Surgery. In: Diseases of the Colon & Rectum. Vol 34. Philadelphia, Pa: Lippincott Williams and Wilkins; 1991:. 285. [Full Text].
Corman ML. Colon and Rectal Surgery. 4th ed. Philadelphia, Pa: Lippincott-Raven; 1998.
Eisenhammer S. The surgical correction of chronic internal anal (sphincteric contracture). S Afr Med J. 1951;25:486.
Gibbons CP, Read NW. Anal hypertonia in fissures: cause or effect?. Br J Surg. Jun 1986;73(6):443-5. [Medline].
Gordon PH, Nivatvongs S. Principles and Practice of Surgery for the Colon, Rectum, and Anus. 2nd ed. New York, NY: Marcel Dekker; 1999.
Hyman NH, Cataldo PA. Nitroglycerin ointment for anal fissures: effective treatment or just a headache?. Dis Colon Rectum. Mar 1999;42(3):383-5. [Medline].
Jost WH, Schimrigk K. Therapy of anal fissure using botulin toxin. Dis Colon Rectum. Dec 1994;37(12):1321-4. [Medline].
Klosterhalfen B, Vogel P, Rixen H, Mittermayer C. Topography of the inferior rectal artery: a possible cause of chronic, primary anal fissure. Dis Colon Rectum. Jan 1989;32(1):43-52. [Medline].
Lewis TH, Corman ML, Prager ED, Robertson WG. Long-term results of open and closed sphincterotomy for anal fissure. Dis Colon Rectum. May 1988;31(5):368-71. [Medline].
Milsom JW, Smith DL, Corman ML, et al. Double-blind comparison of single-dose alatrofloxacin and cefotetan as prophylaxis of infection following elective colorectal surgery. Trovafloxacin Surgical Group. Am J Surg. Dec 1998;176(6A Suppl):46S-52S. [Medline].
Pernikoff BJ, Eisenstat TE, Rubin RJ, et al. Reappraisal of partial lateral internal sphincterotomy. Dis Colon Rectum. Dec 1994;37(12):1291-5. [Medline].
Richard CS, Gregoire R, Plewes EA, et al. Internal sphincterotomy is superior to topical nitroglycerin in the treatment of chronic anal fissure: results of a randomized, controlled trial by the Canadian Colorectal Surgical Trials Group. Dis Colon Rectum. Aug 2000;43(8):1048-57; discussion 1057-8. [Medline].
Rosen L, Abel ME, Gordon PH, et al. Practice parameters for the management of anal fissure. The Standards Task Force American Society of Colon and Rectal Surgeons. Dis Colon Rectum. Feb 1992;35(2):206-8. [Medline].
Schouten WR, Briel JW, Auwerda JJ, De Graaf EJ. Ischaemic nature of anal fissure. Br J Surg. Jan 1996;83(1):63-5. [Medline].
Further Reading
Clinical guidelines:
Practice parameters for the management of anal fissures (revised). American Society of Colon and Rectal Surgeons - Medical Specialty Society. 1992 (revised 2004 Dec). 5 pages. NGC:004075
Practice parameters for the treatment of perianal abscess and fistula-in-ano (revised). American Society of Colon and Rectal Surgeons - Medical Specialty Society. 1996 (revised 2005 Jul). 6 pages. NGC:004432
Clinical trials:
Measurement of Stress During Anesthesia With ”Pain Detector” on Patients Receiving Atropine
Prevention and/or Reduction of Hemorrhoids and/or Thrombosed External Hemorrhoids Using the HEM-AVERT Perianal Stabilizer Instrument
Treatment of Anal Fissure by Activated Human Macrophages
Keywords
anal fissure, fissure, sphincter, anus, constipation, perianal, sphincterotomy, anal canal, treatment fissure, hard stool, anal canal stenosis, bowel movement, anal skin tag, hypertrophied anal papillae, anal canal tear, anal canal crack, tear in anal canal, crack in anal canal, hard stool, anal canal tethering, hypertonic anal sphincter, hypertrophic anal sphincter, anal sphincter hypertonicity, anal sphincter hypertrophy, sphincter stretch
