Benign Anorectal: Abscess and Fistula

1. Benign Anorectal: Abscess and Fistula • Seema Izfar, MD 12/21/11

2. Benign Anorectal: Abscess and Fistula • anorectal abscess and fistula-in-ano represent different stages of the same disease • the abscess represents the acute inflammatory event • the fistula represents the chronic process

3. Benign Anorectal: Abscess and Fistula • diagnosis and treatment requires in-depth understanding of anorectal anatomy and spaces

5. Benign Anorectal: Abscess and Fistula • at the dentate line, the ducts of the anal glands empty into anal crypts • 80% are submucosal, 8% extend to internal sphincter, 8% to the conjoined longitudinal muscle, 2% intersphincteric, 1% penetrate internal sphincter • 90% of anorectal abscess result from crytogladular infection • Parks cryptoglandular theory - obstruction of anal glands leads to stasis and infection

6. Abscess • classified by location: perianal, ischioanal, intersphincteric, supralevator • perianal abscess most common, supralevator most rare • pain, swelling, fever hallmark symptoms • supralevator abscess may have gluteal pain • rectal pain with urinary symptoms - possibly indicate intersphincteric or supralevator abscess

7. Abscess - Etiology • nonspecific cryptoglandular (90%) • specific causes: • inflammatory bowel disease, • specific infection, ie TB, actinomycosis, lymphogranuloma venereum, • trauma or foreign body • surgery (episiotomy, hemorrhoidectomy, prostatectomy), • malignancy - carcinoma, lymphoma, radiation-related

8. Abscess - Treatment • exam under anesthesia for pain out of proportion to exam • incision and drainage - trim edges to prevent coaptation • I&D of supralevator abscess: • depends on location - intersphincteric origin then divide internal sphincter and drain into rectum; if arises from ischianal abscess can be drained through perineal skin

9. Abscess

10. Abscess

11. Abscess - Treatment • catheter drainage: stab incision to drain pus, mushroom catheter in cavity to drain pus • make stab incision as close as possible to anus • size and length of catheter should correspond to abscess cavity

12. Abscess - Treatment • primary fistulotomy • may be easier to identify tract • eliminates source of infection • decreases recurrence/need for reoperation • downsides: false passage formation with acute inflammation, 30-50% of those with abscess likely won’t develop a fistula, need for anesthesia vs. local for I & D

13. Abscess - Antibiotics • little or no role except in case of valvular heart disease, prosthetic devices, severe cellulitis, diabetes, immunosuppression

14. Abscess - Complications • Recurrence • recurrence in as many as 89% of pts • Extra-anal causes • should be evaluated for recurrent disease (hidradenitis suppurativa, Crohn’s) • Incontinence • iatrogenic (superficial external sphincter), inappropriate wound care (excessive scarring from prolonged packing)

15. Abscess - Complications • can result in necrotizing anorectal infection (rare) • resuscitation, IV abx, wide debridement to healthy tissue • need for colostomy debatable - recommended if sphincter muscle is grossly infected, immunocompromised, rectal or colonic involvement/perforation • reexamination under anesthesia • HBO - 100% O2 at 3atm over 2 hrs - promote leukocyte phagocytic function and fibroblast proliferation

16. Anal Infection and Hematologic Diseases • anorectal suppuration with acute leukemia with mortality 45-78% • neutrophil count <500 with 11% incidence of anorectal abscess • most important prognostic factor - # days of neutropenia • presenting symptoms: fever, pain, urinary retention • antibiotics vs I & D if fluctuance, sepsis, or progression of soft tissue infection after antibiotics trial

17. Anal Infection & HIV • HIV+ pts have increased risk of perianal sepsis • can be associated with in situ neoplasia • surgery + antibiotics 2/2 immunosuppression • make incison site small bc pts at risk for poor wound healing

18. Fistula-in-ano • abnormal communication between any two epithelium-lined surfaces • Parks classification:

19. Intersphincteric Fistula-in-ano • most common type of fistula - 70% • results from perianal abscess • variations: • simple low tract • high tract with rectal opening or blind tract • extrarectal extension • pelvic disease tracking

20. Transsphincteric Fistula • approx 23% fistulas • results from ischioanal absecesses • rectovaginal fistula is a form of transsphincteric fistula • operative mgt with setons if sphincter preservation in question

21. Suprasphincteric Fistula • 5% of fistulas • result from supralevator abscesses • tract arises from intersphincteric abscess, travels above puborectalis, then downward lateral to external sphincters in ischioanal space

22. Extrasphincteric Fistula • 2% of fistulas - rarest form • from rectum above the levators, through them, to the perianal skin • trauma, foreign body, Crohn’s carcinoma • most common cause is iatrogenic from probing during fistulotomy surgery

23. Fistula-in-ano: Physical Examination • Goodsall’s rule: • transverse line across the perineum - • posterior external openings have internal openings in the posterior midline • anterior external openings have tract radially toward the nearest crypt • greater distance from anal margin with more variability • more accurate rule for posterior fistulas

24. Fistula-in-ano: Treatment • eliminate fistula, • prevent recurrence, • preserve sphincter function

25. Fistula-in-ano: Treatment • identification of internal opening • passage of probe • injection of dye, milk, or hydrogen peroxide • following granulation in fistula tract • noting puckering of crypt with traction on fistula tract

26. Fistula-in-ano: Operative Management • Lay-open technique: identification of tract with unroofing tract +/- marsupialization • appropriate for simple interspincteric and low transsphincteric

27. Fistula-in-ano: Operative Management • Seton - placement of non-absorbable suture material in fistula tract • indications for setons: • promote fibrosis around fistula tract that encircles entire sphincter mechanism • mark the site of fistula in massive anorectal sepsis • anterior high transsphincteric fistulas in women • HIV pts with poor wound healing and high transsphincteric fistulas • Crohn’s • any time continence is questioned

28. Fistula-in-ano: Operative Management • high-transphincteric fistulas can be treated with combination lay-open technique and seton placement - division of internal sphincter to level of external opening and then seton placement • cutting setons can convert high fistulas to low fistulas • second-stage fistulotomy ~ 8 wks later

29. Fistula-in-ano: Operative Management • suprasphincteric fistula - tract involves external sphincter and puborectalis - • can manage with division of internal sphincter and superficial external sphincter with seton around remaining ES • or internal sphincterotomy, seton, opening of fistula tracts without division of external sphincter

30. Fistula-in-ano: Operative Management • Anorectal Advancement Flap • internal opening closed with absorbable suture, full-thickness flap of rectal mucosa/submucosa/IAS raised - adv 1 cm beyond internal opening • base of the flap should be twice the width of the apex • pros: reduction in healing time, reduced pain, little potential damage to sphincters, lack of deformity to anal canal • poor outcomes in Crohn’s, pts on steroids, smokers, o/w success reported in up to 90% of pts

31. Fistula-in-ano: Operative Management • Fibrin Glue - used in conjuntion with AAF or alone • technique: internal and external openings identified, tract curetted, fistula tract injected through connector from external opening until glue visible in internal opening, slowly withdrawn • can be repeated several times without compromising continence

32. Fistula-in-ano: Operative Management • Fibrin Glue - Followup: • short-term follow-up with good success 70-80% • longer follow-up with success falling to 60% and even 14% in pts with complex anal fistulas

33. Fistula-in-ano: Operative Management • bioprosthetic fistula plug made from surgisis • technique - identification of internal and external opening with placement of plug over probe using suture similar to seton placement • plug secured at primary opening using absorbable suture

34. Fistula-in-ano: Operative Management • technique works best with long tracts without active inflammation or sepsis • short-term follow up (3months) with higher success rate for Crohn’s fistulas when compared to fibrin glue • long-term follow up - high failure rate

35. Crohn’s and Anal Fistulas • the most common perianal manifestation and occur in 6-34% Crohn’s pts - pts with colonic Crohn’s with higher incidence, rectal Crohn’s with 100% fistula formation • conservative approach to treatment as 38% heal without surgery

36. Crohn’s and Anal Fistulas • medications for treatment: cipro/flagyl, immunomodulators (steroids, 6MP, azathioprine, infliximab) • 6-MP and azathioprine only effective in 1/3 pts with fistulizing Crohn’s • Infliximab associated with 62% reduction • combination 6MP and infliximab may prolong effect of treatment • selective seton placement with infliximab + maintenance med with healing in 67%

37. Crohn’s and Anal Fistulas • operative intervention: seton placement, rectal advancement flap if rectal-sparing, poss fibrin glue/plug • avoid cutting sphincter - incontinence reported in pts with Crohn’s proctitis even without anal surgery