Anal Fistula2

Anatomy Recall Illustration

Anal Disorders Fistula-in-Ano Background A fistula-in-ano is a hollow tract lined with granulation tissue connecting: a primary opening inside the anal canal to a secondary opening in the perianal skin Secondary tracts may be multiple

Anal Disorders Fistula-in-Ano Background A symptomatic fistula-in-ano requires surgery, because spontaneous healing is very rare The objective of fistula surgery is to cure the fistula: with the lowest possible recurrence rate and with minimal, if any, change in

Anal Disorders Fistula-in-Ano Background To accomplish this, the surgeon must understand the ramifications of fistulous tracts The classification system described by Parks and colleagues serve as a guide to surgical treatment

Anal Disorders Fistula-in-Ano Background Frequency: The prevalence rate is 8.6 cases per 100,000 population The prevalence: In men is 12.3 cases per 100,000 population In women, it is 5.6 cases per 100,000 population

Anal Disorders Fistula-in-Ano Background Etiology Fistula-in-ano is nearly always caused by a previous anorectal abscess Anal canal glands situated at the dentate line afford a path for infecting organisms to reach the intramuscular spaces

Anal Disorders Fistula-in-Ano Background Etiology Other fistulae develop secondary to: trauma Crohn disease anal fissures carcinoma radiation therapy actinomycoses tuberculosis and chlamydial infections

Anal Disorders Fistula-in-Ano Background Pathophysiology The cryptoglandular hypothesis states that: (1) an infection begins in the anal gland and (2) progresses into the muscular wall of the anal sphincters to cause (3) an anorectal abscess

Anal Disorders Fistula-in-Ano Background Pathophysiology Following surgical or spontaneous drainage in the perianal skin, occasionally a “granulation tissue–lined tract” is left behind, causing recurrent symptoms Multiple series have shown that the formation of a fistula tract following anorectal abscess occurs in 7- 40% of cases

Anal Disorders Fistula-in-Ano Clinical History Signs and symptoms; in order of prevalence 1) Perianal discharge 2) Pain 3) Swelling 4) Bleeding 5) Diarrhea 6) Skin excoriation 7) External opening

Fistula-in-Ano Clinical Past medical history * Inflammatory bowel disease * Diverticulitis * Previous radiation therapy for: prostate or rectal cancer * Tuberculosis * Steroid therapy * HIV infection

Anal Disorders Fistula-in-Ano Clinical Review of symptoms Abdominal pain Weight loss Change in bowel habits

Anal Disorders Fistula-in-Ano Clinical Physical examination Physical examination findings remain the mainstay of diagnosis

Anal Disorders Fistula-in-Ano Clinical Physical examination The examiner should observe the entire perineum, looking for an external opening that appears as: an open sinus or elevation of granulation tissue

Anal Disorders Fistula-in-Ano Clinical Physical examination Spontaneous discharge via the external opening may be: apparent or expressible upon digital rectal examination

Anal Disorders Fistula-in-Ano Clinical Physical examination Digital rectal examination may reveal: a fibrous tract cord beneath the skin or acute inflammation that is not yet drained

Anal Disorders Fistula-in-Ano Clinical Physical examination The examiner should determine the relationship between the anorectal ring and the position of the tract before the patient is relaxed by anesthesia

Anal Disorders Fistula-in-Ano Clinical Physical examination The sphincter tone and voluntary squeeze pressures should be assessed before any surgical intervention to delineate whether preoperative manometry is indicated Anoscopy is usually required to identify the internal opening

Anal Disorders Fistula-in-Ano Clinical Differential diagnoses The following do not communicate with the anal canal: Hidradenitis suppurativa Infected inclusion cysts Pilonidal disease Bartholin gland abscess in females

Anal Disorders Fistula-in-Ano Indications Therapeutic intervention is indicated for symptomatic patients If patients are without symptoms and a fistula is found during a routine examination, no therapy is required

Anal Disorders Fistula-in-Ano Parks Classification System The Parks classification system defines 4 types of fistula-in-ano that result from cryptoglandular infections

Parks Classification System Intersphincteric Common course - Via internal sphincter to the intersphincteric space and then to the perineum Simple intersphincteric fistula * 70% of all anal fistulae

• Parks Classification System (Fistula-in-Ano) • Intersphincteric Other possible tracts a)Intersphincteric fistula with a high blind tract

b) Intersphincteric fistula with high tract opening into the lower rectum c) High intersphincteric without a perineal opening d) Intersphincteric fistula from pelvic disease

Fistula-in-Ano Parks Classification System Transsphincteric Common course - Low via internal and external sphincters into the ischiorectal fossa and then to the perineum

25% of all anal fistulae Other possible tracts: * High tract with perineal opening * high blind tract

Fistula-in-Ano Parks Classification System Suprasphincteric Common course - Via intersphincteric space superiorly to above puborectalis muscle into ischiorectal fossa and then to perineum

5% of all anal fistulae

Anal Disorders Fistula-in-Ano Background Parks Classification System Extrasphincteric Common course The tract begins at the rectum or sigmoid colon and extend downward, passes through the levator ani muscle and then to perineum around the anus 1% percent of all anal fistulae

Anal Disorders Fistula-in-Ano Contraindications: Surgery for fistula-in-ano should not be performed for definitive repair of the fistula in the setting of anorectal abscess i.e. unless the fistula is superficial and the tract is obvious)

Anal Disorders Fistula-in-Ano Workup Lab studies No specific laboratory studies are required The normal preoperative studies are performed based on: age and comorbidities

Anal Disorders Fistula-in-Ano Imaging Studies Radiologic studies: These are not performed for routine fistula evaluation They can be helpful when 1) the primary opening is difficult to identify or in the case of 2) recurrent or 3) multiple fistulae to identify secondary tracts or missed primary openings

Anal Disorders Fistula-in-Ano Background Imaging Studies Fistulography This involves injection of contrast via the internal opening, which is followed by x-ray images to outline the course of the fistula tract

Imaging Studies Endoanal/endorectal ultrasound These studies help to define muscular anatomy differentiating: * intersphincteric from * transsphincteric lesions CT scan A CT scan is more helpful: * in the setting of perirectal inflammatory disease than * in the setting of small fistulae

Anal Disorders Fistula-in-Ano Background Imaging Studies MRI Is becoming the study of choice when evaluating complex fistulae It has been shown to improve recurrence rates by providing information on otherwise unknown extensions

Anal Disorders Fistula-in-Ano Background Imaging Studies A barium enema This is useful for patients with: multiple fistulae or recurrent disease to help rule out IBD

Other Tests Anal manometry Pressure evaluation of the sphincter mechanism is helpful in certain patients 1) Decreased tone observed during preoperative evaluation 2) History of previous fistulotomy 3) History of obstetrical trauma 4) High transsphincteric or suprasphincteric fistula (if known) 5) Very elderly patients

Anal Disorders Fistula-in-Ano Diagnostic Procedures Examination under anesthesia An examination of the perineum: * digital rectal examination and * anoscopy are performed after the anesthesia of choice is administered

Diagnostic Procedures This examination is necessary before surgical intervention, especially if outpatient evaluation causes: 1) discomfort or 2) has not helped delineate the course of the fistulous process Several techniques have been described to help locate the course of the fistula and, more importantly, identify the internal opening

Anal Disorders Fistula-in-Ano Diagnostic Procedures Inject hydrogen peroxide milk or dilute methylene blue into the external opening and watch for egress at the dentate line

Anal Disorders Fistula-in-Ano Diagnostic Procedures Insertion of a blunt-tipped crypt probe via the external opening may help outline the direction of the tract

Anal Disorders Fistula-in-Ano Diagnostic Procedures * Proctosigmoidoscopy * Colonoscopy * Rigid sigmoidoscopy can be performed at the initial evaluation to help rule out any associated disease process in the rectum

Anal Disorders Fistula-in-Ano Treatment Medical therapy No definitive medical therapy is available

Anal Disorders Fistula-in-Ano Treatment Surgical therapy Fistulotomy/fistulectomy/seton

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