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Anal Fistulotomy

  • Author: Vassiliki L Tsikitis, MD; Chief Editor: Kurt E Roberts, MD  more...
 
Updated: Jul 22, 2016
 

Background

Anorectal abscess, which can be an incapacitating condition, originates from a cryptoglandular infection in the anal canal. Anal fistula, or fistula-in-ano, is a persistent, abnormal tract from the anal canal to the perianal skin, and is estimated to occur in 50% of patients with anorectal abscess.[1]

Anal fistulae are hollow tracts lined with granulation tissue connecting a primary (internal) opening inside the anal canal to a secondary (external) opening in the perianal skin. Obstruction of anal crypt glands leads to suppuration, which then forms a tract into an anorectal space; the direction taken determines the anorectal abscess location and hence the type of fistula. To understand the different types of anal fistulae (see Technical Considerations), clinicians must be familiar with the different anorectal spaces from which abscesses arise (see the image below).

Anorectal spaces. Anorectal spaces.

Whereas treating an abscess can be rather straightforward, treating an anorectal fistula can be difficult for the surgeon and frustrating for the patient. Treatment of anorectal fistulae also varies according to the location, severity, and chronicity of the fistula tract.

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Indications

All anal fistulae should be treated surgically. The goal of treatment is to obliterate the internal fistulous opening, including associated epithelialized tracts, with minimal sphincter division (preservation of sphincter function) and prevention of recurrence.

The type of procedure performed depends on the type of fistula (see Technical Considerations). Thus, the first step in surgical treatment is to identify the anatomy, including the external and internal opening, and define the course of all tracts relative to the sphincter muscles. This maneuver almost always requires that the patient be anesthetized. The external opening is usually more apparent, and identifying the internal opening can be challenging.

Many principles and maneuvers have been devised to assist in this task, including the Goodsall rule, which is as follows (see the image below):

  • All fistula tracts with external openings within 3 cm of the anal verge and posterior to a line drawn through the ischial spines travel in a curvilinear fashion to the posterior midline; if the distance between the external opening and anal margin exceeds 3 cm, there is an increased chance of complicated extensions of the fistula tract
  • All tracts with external openings anterior to this line enter the anal canal in a radial fashion
The Goodsall rule. The Goodsall rule.

According to the literature, Goodsall’s rule accurately predicts the location of the internal opening in 49-81% of patients.[2] The external opening location can be a poor predictor of fistula location in patients with long fistula tracts, recurrent fistulae, or Crohn disease.[3, 4, 5]

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Contraindications

All symptomatic anorectal fistulae require anal fistulotomy. The only exceptions are in patients with Crohn disease. The primary treatment for perianal Crohn fistulae is medical (ie, immunologic agents), and surgery is reserved for control of perianal sepsis, where less is more (eg, placement of draining setons).[6]

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Technical Considerations

Anatomic considerations

Anatomy of anal canal and surrounding structures

A solid knowledge of the anatomy of the anal canal, the perirectal tissues and the sphincteric muscles is a prerequisite for any operative treatment of anal fistula.

The surgical anal canal, which is approximately 2-4 cm long, is located between the anorectal ring (a palpable convergence of the internal sphincter, the deep external sphincter, and the puborectalis) superiorly and extends inferiorly to the anal verge (the junction of the anal canal and the hair-bearing keratinized perineal skin). The lining of the anal canal is composed of columnar cells, transitional epithelium, and non-hair-bearing squamous epithelium.

The anal canal is surrounded by two layers of funnel-shaped musculature. The inner muscular structure is the internal anal sphincter, which is the lowermost continuation of the inner, circular muscle layer of the rectum and is under involuntary control. The outer musculature is formed by the puborectalis (innermost fibers of the levator ani) and the external anal sphincter. The external anal sphincter has three parts—subcutaneous, superficial, and deep—and is under voluntary control .

The dentate line, which is about 1-2 cm proximal to the anal verge or the midportion of the anal canal, is the embryologic fusion point between endoderm and ectoderm and marks a separation between innervation, arterial-venous blood supply, and lymphatic drainage. At the level of the dentate line, a cryptoglandular complex consisting of four to eight apocrine anal glands from the intersphincteric space exist that empty via anal ducts through the internal anal sphincter into the anal canal.

The intersphincteric groove is the space between the internal and external anal sphincters and can be palpated approximately 1 cm below the dentate line near the level of the anal verge. The anal margin is outside of the anal verge and is characterized by radial skin folds, thicker skin, pigmentation, and skin with adnexal tissues.

For more information about the relevant anatomy, see Anal Canal Anatomy.

Classification of fistula types

The Parks classification system, which describes the fistula tracts in relation to the anal sphincter complex, defines the following four types of fistula-in-ano resulting from cryptoglandular infections[7] :

  • Intersphincteric
  • Transsphincteric
  • Suprasphincteric
  • Extrasphincteric

Intersphincteric fistulae (see the image below) account for about 70% of all anal fistulae and usually result from a perianal abscess. The tract is via the internal sphincter to the intersphincteric space, and then out to the perineum. No external sphincter is involved. Other possible tracts include a blind tract with no perineal opening and a high tract to the lower rectum or pelvis.

Intersphincteric fistula. Intersphincteric fistula.

Transsphincteric fistulae (see the image below) account for about 25% of all anal fistulae and usually arise from an ischioanal abscess. The tract traverses both internal and external sphincters and passes into the ischiorectal fossa and then to the perineum. Other possible tracts include a high tract with perineal opening and a high blind tract.

Transsphincteric fistula. Transsphincteric fistula.

Suprasphincteric fistulae (see the image below) account for about 5% of all anal fistulae and usually result from a supralevator abscess. The tract arises in the intersphincteric space and courses superiorly above the puborectalis into the ischiorectal fossa and then to the perineum.

Suprasphincteric fistula. Suprasphincteric fistula.

Extrasphincteric fistulae (see the image below) account for only about 1% of all anal fistulae. Causes include iatrogenic injury from probing, penetrating injury to the perineum or rectum, Crohn disease, and carcinoma or its treatment. The tract passes from the rectum above the levators and through the levator ani muscles to the perianal skin completely outside the sphincter mechanism.

Extrasphincteric fistula. Extrasphincteric fistula.

Additionally, anal fistulae can be classified as either simple or complex, as follows[3] :

  • Simple fistulae include intersphincteric fistulae and low transsphincteric fistulae that cross less than 30% of the external sphincter
  • Complex fistulae include high transphincteric fistulae (with or without a high blind tract), suprasphincteric fistulae, and extrasphincteric fistulae, in addition to recurrent fistulae; rectovaginal fistulae, fistulae involving multiple tracts, anterior fistulae in women (higher risk for postfistulotomy incontinence); and fistulae associated with inflammatory bowel disease, radiation, malignancy or preexisting incontinence
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Contributor Information and Disclosures
Author

Vassiliki L Tsikitis, MD Associate Professor of Surgery, Department of Surgery, Division of General and Gastrointestinal Surgery, Oregon Health and Science University School of Medicine

Vassiliki L Tsikitis, MD is a member of the following medical societies: American College of Surgeons, American Society of Colon and Rectal Surgeons, Association for Academic Surgery, Society for Surgery of the Alimentary Tract, SWOG, Association of Women Surgeons, Pacific Coast Surgical Association

Disclosure: Nothing to disclose.

Coauthor(s)

Nicole EK Wieghard, MD Resident Physician, Department of Surgery, Oregon Health and Science University School of Medicine

Nicole EK Wieghard, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Surgeons, Association of Women Surgeons

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Chief Editor

Kurt E Roberts, MD Assistant Professor, Section of Surgical Gastroenterology, Department of Surgery, Director, Surgical Endoscopy, Associate Director, Surgical Skills and Simulation Center and Surgical Clerkship, Yale University School of Medicine

Kurt E Roberts, MD is a member of the following medical societies: American College of Surgeons, Society of American Gastrointestinal and Endoscopic Surgeons, Society of Laparoendoscopic Surgeons

Disclosure: Nothing to disclose.

Additional Contributors

Kurt E Roberts, MD Assistant Professor, Section of Surgical Gastroenterology, Department of Surgery, Director, Surgical Endoscopy, Associate Director, Surgical Skills and Simulation Center and Surgical Clerkship, Yale University School of Medicine

Kurt E Roberts, MD is a member of the following medical societies: American College of Surgeons, Society of American Gastrointestinal and Endoscopic Surgeons, Society of Laparoendoscopic Surgeons

Disclosure: Nothing to disclose.

Acknowledgements

The authors and editors of Medscape Drugs & Diseases thank Francisco Javier Reyes Martin, MD, Resident Physician, Department of Surgery, University of Arizona College of Medicine, for his contributions to an earlier version of this topic.

References
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  2. Cirocco WC, Reilly JC. Challenging the predictive accuracy of Goodsall's rule for anal fistulas. Dis Colon Rectum. 1992. 35(6):537-542.

  3. Steele SR, Kumar R, Feingold DL, Rafferty JL, Buie WD. Standards Practice Task Force of the American Society of Colon and Rectal Surgeons. Practice parameters for the management of perianal abscess and fistula-in-ano. Dis Colon Rectum. 2011. 54(12):1465-1475.

  4. Gunawardhana PA, Deen KI. Comparison of hydrogen peroxide instillation with Goodsall's rule for fistula-in-ano. ANZ J Surg. 2001. 71(6):472-474.

  5. Coremans G, Dockx S, Wyndaele J, Hendrickx A. Do anal fistulas in Crohn's disease behave differently and defy Goodsall's rule more frequently than fistulas that are cryptoglandular in origin?. Am J Gastroenterol. 2003. 98(12):2732-2735.

  6. Geltzeiler CB, Wieghard N, Tsikitis VL. Recent developments in the surgical management of perianal fistula for Crohn’s disease. Ann Gastroenterol. 2014. 27(4):1-11.

  7. Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg. 1976. 63:1-12.

  8. Garcia-Olmo D, Herreros D, Pascual I, Pascual JA, Del-Valle E, Zorrilla J, et al. Expanded adipose-derived stem cells for the treatment of complex perianal fistula: a phase II clinical trial. Dis Colon Rectum. 2009 Jan. 52 (1):79-86. [Medline].

  9. Herreros MD, Garcia-Arranz M, Guadalajara H, De-La-Quintana P, Garcia-Olmo D, FATT Collaborative Group. Autologous expanded adipose-derived stem cells for the treatment of complex cryptoglandular perianal fistulas: a phase III randomized clinical trial (FATT 1: fistula Advanced Therapy Trial 1) and long-term evaluation. Dis Colon Rectum. 2012 Jul. 55 (7):762-72. [Medline].

  10. Guadalajara H, Herreros D, De-La-Quintana P, Trebol J, Garcia-Arranz M, Garcia-Olmo D. Long-term follow-up of patients undergoing adipose-derived adult stem cell administration to treat complex perianal fistulas. Int J Colorectal Dis. 2012 May. 27 (5):595-600. [Medline].

  11. Dudukgian H, Abcarian H. Why do we have so much trouble treating anal fistula?. World J Gastroenterol. 2011. 17(28):3292-3296.

  12. Ritchie RD, Sackier JM, Hodde JP. Incontinence rates after cutting seton treatment for anal fistula. Colorectal Dis. 2009. 11(6):564-571.

  13. van Tets WF, Kuijpers HC. Continence disorders after anal fistulotomy. Dis Colon Rectum. 1994. 37(12):1194-7.

  14. Williams JG, MacLeod CA. Seton treatment of high anal fistulae. Br J Surg. 1991 Oct. 78(10):1159-61.

  15. Lindsey I, Smilgin-Humphreys MM, Cunningham C, Mortensen NJ, George BD. A randomized, controlled trial of fibrin glue vs conventional treatment for anal fistula. Dis Colon Rectum. 2002. 45:1608-1615.

  16. Sentovich SM. Fibrin glue for anal fistulas: long-term results. Dis Colon Rectum. 2003. 46:498-502.

  17. Swinscoe MT, Ventakasubramaniam AK, Jayne DG. Fibrin glue for fistula-in-ano: the evidence reviewed. Tech Coloproctol. 2005. 9:89-94.

  18. Yeung JM, Simpson JA, Tang SW, et al. Fibrin glue for the treatment of fistulae in ano—a method worth sticking to?. Colorectal Dis. 2010. 12(4):363-366.

  19. de Parades V, Far HS, Etienney I, Zeitoun JD, Atienza P, Bauer P. Seton drainage and fibrin glue injection for complex anal fistulas. Colorectal Dis. 2010. 12(15):459-463.

  20. Song WL, Wang ZJ, Zheng Y, Yang XQ, Peng YP. An anorectal fistula treatment with acellular extracellular matrix: a new technique. World J Gastroenterol. 2008. 14:4791-4794.

  21. Ellis CN, Rostas JW, Greiner FG. Long-term outcomes with the use of bioprosthetic plugs for the management of complex anal fistulas. Dis Colon Rectum. 2010. 53:798-802.

  22. Mushaya C, Bartlett L, Schulze B, Ho YH. Ligation of intersphincteric fistula tract compared with advancement flap for complex anorectal fistulas requiring initial seton drainage. Am J Surg. 2012. 204(3):283-289.

  23. Tan KK, Alsuwaigh R, Tan AM, et al. Which surgery to perform following seton insertion for high anal fistula?. Dis Colon Rectum. 2012. 55(12):1273-1277.

  24. Cavanaugh M, Hyman N, Osler T. Fecal incontinence severity index after fistulotomy: a predictor of quality of life. Dis Colon Rectum. 2002. 45(3):349-53.

  25. Mylonakis E, Katsios C, Godevenos D, Nousias B, Kappas AM. Quality of life of patients after surgical treatment of anal fistula; the role of anal manometry. Colorectal Dis. 2001. 3(6):417-21.

 
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Anorectal spaces.
Intersphincteric fistula.
Transsphincteric fistula.
Suprasphincteric fistula.
Extrasphincteric fistula.
The Goodsall rule.
Seton.
Anorectal advancement flap. A) Transsphincteric fistula-in-ano. B) Enlargement of external opening and curettage of granulation tissue. C) Mobilization of flap and closure of internal opening. D) Suturing of flap covering internal opening.
Fistula plug technique.
 
 
 
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