Fistula in ano

Fistula in ano

1. FISTULA-IN- ANO Dr. Raju Khatiwada Resident General surgery KISTMCTH

2. CONTENTS ANATOMY OF THE ANAL REGION INTRODUCTION CLASSIFICATION CLINICAL ASSESSMENT IMAGING STUDIES MANAGEMENT TAKE HOME MESSAGE REFERENCES

3. ANATOMY The anal canal, as defined by the surgeon/clinician, is approximately 4 cm in length, extending from the anal verge to the top of anorectal ring. A natomist considers the anus to be the 2 cm from the anal verge to the dentate line. Bailey and love textbook of surgery, 27th edition

4. INTERNAL ANAL SPHINCTER EXTERNAL ANAL SPHINCTER Thickened (2–5 mm) distal continuation of the circular muscle coat of the rectum. The external anal sphincter is a funnel shaped structure composed of the pelvic floor muscles enveloping the distal rectum and anus This is involuntary muscle. Voluntary muscle The internal anal sphincter is supplied by sympathetic (L5) and parasympathetic (S2, S3, and S4) nerves The external anal sphincter is innervated on each side by the inferior rectal branch of the pudendal nerve (S2 and S3) and by the perineal branch of S4. SUBDIVIDED INTO: Deep Superficial subcutaneous

5. ANORECTAL VASCULAR AND LYMPHATIC SUPPLY Schwartz textbook of surgery, 11th edition.

6. FISTULA-IN-ANO DEFINITION: It is a chronic abnormal communication , usually lined to some degree by granulation tissue, which runs outwards from the anorectal lumen (the internal opening ) to an external opening on the skin of the perineum or buttock (or rarely, in women, to the vagina ). Drainage of an anorectal abscess results in cure for about 50% of patients. The remaining 50% develop a persistent fistula in ano.

7. Epidemiology The overall incidence is about 9 cases per 100 000 population per year in western Europe. Age: third , fourth and fifth decades of life are most commonly affected Sex: More common in men than women.

8. ETIOLOGY The most common etiology of an anorectal fistula is an infected anal crypt gland. M ay be found in association with specific conditions, such as Crohn’s disease, T uberculosis , L ymphogranuloma venereum , Actinomycosis , R ectal duplication, F oreign body and Malignancy Non-specific , idiopathic or cryptoglandular, and intersphincteric anal gland infection is deemed central to them.

9. CLASSIFICATION Park’s classification High and low fistula in ano Simple and complex fistula in ano

10. Park’s classification Based on the centrality of intersphincteric anal gland sepsis (the internal opening is usually at the dentate line), which results in a primary track whose relation to the external sphincter defines the type of fistula and which influences management Sabiston’s textbook of surgery-21 st Edition

11. INTERSPHINCTERIC: TRANSSPHINCTERIC 45% 30% Do not cross the external sphincter Have a primary track that crosses both internal and external sphincters (the latter at a variable level) and which then passes through the ischiorectal fossa to reach the skin of the buttock. Most commonly they run directly from the internal to the external openings across the distal internal sphincter But may extend proximally in the intersphincteric plane to end blindly with or without an abscess (high blind tract), or Rectal opening without perineal opening

12. SUPRASPHINCTERIC FISTULAE EXTRASPHINCTERIC FISTULAE Very rare Run without specific relation to the sphincters Fistula originates at the anal crypt and encircles the entire sphincter apparatus, and terminates in the ischiorectal fossa Iatrogenic Typically not cryptoglandular in origin Result from pelvic disease or trauma Difficult to distinguish from high-level trans- sphincteric tracks

13. Simple fistulas Low-lying transsphincteric (Parks' type 2 and involving <30 percent of anal sphincter complex) and Intersphincteric fistulas (Parks' type 1)  T raditional approach to treatment is primary fistulotomy

14. Complex fistula A complex fistula refers to those fistulas that have a high risk of treatment failure and cannot be safely treated by routine fistulotomy.

15. An anal fistula is defined as complex in the following situations: Any fistula involving more than 30 percent of the external sphincter Suprasphincteric fistulas Extrasphincteric or high fistulas, proximal to the dentate or pectinate line Women with anterior fistulas Fistulas with multiple tracts Recurrent fistulas Fistulas related to inflammatory bowel disease Fistulas related to infectious diseases, including tuberculosis and HIV Fistulas secondary to local radiation treatments Patients with a history of anal incontinence Rectovaginal fistulas

16. CLINICAL PRESENTATION Patients usually complain of intermittent purulent discharge (which may be bloody) Rectal pain (which increases until temporary relief occurs when the pus discharges). There is often, but not invariably, a previous episode of acute anorectal sepsis that settled ( incompletely ) spontaneously or with antibiotics, or which was surgically drained. T he passage of flatus or faeces through the external opening is suggestive of a rectal rather than an anal internal  opening.

17.  PHYSICAL EXAMINATION: Perianal skin may be excoriated and inflamed An indurated tract is often palpable Palpable cord leading from the external opening to the anal canal may be present

18. The key points in physical examination T o determine the site of the internal opening; The site of the external opening(s) T he course of the primary track The presence of secondary extensions; and The presence of other conditions complicating the fistula. Palpable induration between external opening and anal margin suggests a relatively superficial track, Whereas supralevator induration suggests a primary track above the levators or high in the roof of the ischiorectal fossa, or a high secondary extension. Intersphincteric fistulae usually have an external opening close to the anal verge.

19. Goodsall’s rule Although the external opening is often easily identifiable, identification of the internal opening may be more challenging Goodsall’s rule can be used as a guide in determining the location of the internal opening

20. Full examination under anaesthesia (EUA) should be repeated before surgical intervention . Dilute hydrogen peroxide, instilled via the external opening Gentle use of probes and a finger in the anorectum usually delineates primary and secondary tracks and their relations to the sphincters.

21. IMAGING STUDIES Pelvic MRI is ‘ gold standard’ for fistula imaging The great advantage of MRI is, it demonstrates secondary extensions , which may be missed at surgery and which are the cause of persistence and delineate the anatomy of the fistula tracks Anal fistulography and computed tomography (CT) both have limitations but are useful techniques if an extrasphincteric fistula is suspected . Endoanal ultrasound, gives information about sphincter integrity

22. A meta-analysis showed that, for assessment of anal fistulas, MRI has a sensitivity of 87 percent and a specificity of 69 percent; EUS has a sensitivity of 87 percent and a specificity of 43 percent Siddiqui MR , Ashrafian H, et al. A diagnostic accuracy meta-analysis of endoanal ultrasound and MRI for perianal fistula assessment. Dis Colon Rectum. 2012 May;55(5):576-85. doi : 10.1097/DCR.0b013e318249d26c. PMID : 22513437.

23. Management Surgery is the mainstay of therapy with the ultimate goal of D raining local infection, E radicating the fistulous tract, and A voiding recurrence while preserving native sphincter function . The surgical approach depends upon correct classification of the fistula Alternatively, a draining seton may be used to keep the fistula tract open, which often prevents recurrent abscess

24. SURGICAL MANAGEMENT Simple intersphincteric fistulas: can often be treated by lay-open fistulotomy (opening the fistulous tract), curettage, and healing by secondary intention Complex fistula: Draining seton placed to preserve the sphincter mechanism and help eradicate the septic focus. In six or more weeks, a second sphincter-sparing procedure can be performed after drainage diminishes

25. Procedure selection High transsphincteric fistula : either an Endoanal advancement flap or LIFT Suprasphincteric fistula : Suprasphincteric fistulas (Parks' type 3) should be treated with Endoanal advancement flaps. LIFT is not an option, because there is no intersphincteric fistula tract . Extrasphincteric fistula : Extrasphincteric fistulas (Parks' type 4) are typically not of cryptoglandular origin but are instead caused by cancer or Crohn disease. These fistulas are rare but difficult to treat. Surgical options include proctectomy or fecal diversion.

26. Recurrent fistula : Recurrent fistulas that involve the sphincter complex typically warrant a pelvic magnetic resonance imaging (MRI) scan to clarify anatomy and a seton for drainage. M anaged according to their classification

27. PROCEDURE Fistulotomy Fistulectomy S eton- cutting/draining E ndorectal advancement flap LIFT (ligation of the intersphincteric fistula tract) Fibrin glue D iversion

28. FISTULOTOMY It involves division of all those structures lying between the external and internal openings. It is therefore applied mainly to intersphincteric fistulae and trans-sphincteric fistulae involving less than 30% of the voluntary musculature (simple fistulae) If the fistula tract courses higher into the sphincter mechanism, seton placement is done Patients should be observed for a minimum of six months following the procedure before determining a treatment failure or success

29. Fistulotomy The recurrence rate for treatment of simple anal fistulas with fistulotomy is 2% to 8% and F unctional impairment generally between 0% and 17 %.

30. Fistulectomy Excision of the fistula Complete fistulectomy creates larger wound that takes lomger to heal and offers no recurrence advantage over fistulotomy Diathermy cautery is used I t allows better definition of fistula anatomy than fistulotomy, especially the level at which the track crosses the sphincters and the presence of secondary extensions .

31. Seton Seton is a thread of nylon, prolene, rubber or other material that is non-absorbable and is placed through the fistula track with the purpose of keeping it open for certain period of time Can be Loose seton or tight/cutting seton

32. USES OF LOOSE SETONS For long-term palliation : to avoid septic and painful exacerbations by establishing effective drainage; most often in Crohn’s disease Used before ‘advanced’ techniques (fistulectomy, advancement flap, cutting seton): acute sepsis and secondary extensions are eradicated and a loose seton is passed across the sphincteric component of the primary track to simplify the fistula and allow fibrosis. As part of a staged fistulotomy. As part of a therapeutic strategy to preserve the external sphincter in trans-sphincteric fistulae.

33. Cutting setons Cutting setons placed through the fistula and intermittently tightened in the office. Tightening the seton results in fibrosis and gradual division of the sphincter, thus eliminating the fistula while maintaining continuity of the sphincter The two most important complications of a fistulotomy with a snug seton (cutting) are recurrence and incontinence. The success rates for snug setons range from 82 to 100 percent; however, long-term incontinence rates can exceed 30 percent Patton V, Chen CM, Lubowski D. Long-term results of the cutting seton for high anal fistula. ANZ J Surg. 2015 Oct;85(10):720-7. doi : 10.1111/ans.13156. Epub 2015 May 21. PMID : 25997475.

34. Endorectal advancement flap Higher fistulas may be treated by an endorectal advancement flap The endoanal and endorectal advancement flaps preserve the anal sphincter by closing off the internal opening of the fistula by a mobilized flap of healthy tissue The key component of this procedure is to create a flap that includes the mucosa, submucosa , and a portion of the circular muscular fibers that is sufficient to cover the internal opening.   The base of the flap proximally should measure at least twice its width at the apex.

35. Outcome of Endorectal advancement flap A variety of endoanal advancement flap techniques exist and, in experienced hands, have low-to-moderate recurrence rates (0 to 40 percent), depending in part on patient population, and tolerable incontinence rates ranging from 0 to 12.5 percent  van Koperen PJ , Wind J, Bemelman WA, Bakx R, Reitsma JB , Slors JF . Long-term functional outcome and risk factors for recurrence after surgical treatment for low and high perianal fistulas of cryptoglandular origin. Dis Colon Rectum. 2008 Oct;51(10):1475-81. doi : 10.1007/s10350-008-9354-9. Epub 2008 Jul 15. PMID : 18626715.

36. LIFT (ligation of the intersphincteric fistula tract) Sphincter-preserving procedure, first described in 2006 for trans-sphincteric fistulae. The technique involves disconnection of the internal opening from the fistula tract at the level of the intersphincteric plane and removal of the residual infected glands without diving any part of the sphincter complex. The tract is then ligated and divided , the internal part is removed and the external part of the track is curretted out and drained. Success in terms of healing have been quoted at anything from 47% to 95%.

37. LIFT LIFT can be used to treat both simple and complex fistulas. Fistula tract longer than 3 cm, previous procedures, and obesity have been associated with LIFT failure Outcomes data vary depending on the type of fistulas. Meta-analyses report that the standard LIFT procedure achieved fistula healing in 61 to 94 percent of patients in four to eight weeks, with low morbidity (14 percent) and rare fecal incontinence (1.4 percent)  Hong KD , Kang S, Kalaskar S, Wexner SD. Ligation of intersphincteric fistula tract (LIFT) to treat anal fistula: systematic review and meta-analysis. Tech Coloproctol . 2014 Aug;18(8):685-91. doi : 10.1007/s10151-014-1183-3. Epub 2014 Jun 24. PMID : 24957361.

38. POST OPERATIVE COMPLICATIONS Bleeding Fecal impaction Recurrence Incontinence Anal stenosis

39. Take home message Confirmation of the anatomy of the fistula Surgical management is the mainstay of therapy Use staged procedure Reduce to a simple tract- using draining seton Use non diversion technique Patients with a recurrent fistula require a pelvic magnetic resonance imaging (MRI) scan to clarify anatomy and a seton for drainage Reassess the situation after each intervention

40. REFERENCES Bailey and love textbook of surgery, 27th edition Sabiston’s textbook of surgery-21 st Edition Schwartz textbook of surgery, 11th edition. Uptodate

41. THANK YOU ! ANY QUESTION?