Perianal abscess & Anal fistulae By Rajeev Suryavanshi Dept of General Surgery.

Perianal abscess Definition - Infection of the soft tissue surrounding the anal canal, with formation of discrete abscess cavity. Often cavity is associated with fistulous tract.

Anorectal anatomy Rectum develops from hind gut at 6 weeks Anal canal formed at 8 weeks – ectoderm. Dentate line transition from endo to ecto. Rectum has inner – circular. outer – longitudinal. Anal canal – 4cm, pelvic diaphragm to anal verge.

Anatomy External Sphincter- - U shaped , continuation of levator ani - deep segment is continuous with puborectalis muscle and forms anorectal ring felt on DRE. - striated muscle - voluntary control - 3 components - sub mucous, superficial and deep.

Anatomy- Internal sphincter- - smooth muscle - autonomic control - extension of circular muscles of rectum. - contracted at rest.

Anatomy 4-8 anal glands drained by respective crypts, at dentate line. Gland body lies in intersphincteric plane. Anal gland function is lubrication. Columns of Morgagni 8-14 long mucosal fold.

Pathophysiology Infection starts in crypto glandular epithelium lining the anal canal. Internal anal sphincter a barrier to infection passing from gut to deep perirectal tissue. Duct of Anal gland penetrate internal sphincter into intersphincteric space. Once infection sets in intersphincteric space it can spread further.

Pathophysiology

Frequency Common in 3rd and 4th decade of life Male > female (2:1) 30% present with previous episodes. Increase incidence during summer and spring. Common in infants , poorly understood mechanism , fairly benign and majority settle with simple drainage.

Etiology Abscess initially forms in the intersphincteric space and spreads along adjacent potential spaces. Common organisms- * E.Coli * Enterococcus species * Bacteroides species.

Etiology Less common causes - Crohn’s Disease. Cancer. Tuberculosis. Trauma. Leukemia. Lymphoma.

Clinical features Symptoms- Pain Perianal movement ↑ pressure ↑ Pruritis Generally unwell. Fever Chill and rigor. Signs- Swelling Cellulitis induration Fluctuation Subcutaneous mass, near Perianal orifice. DRE- fluctuation at times in ischorectal.

Classification of Anorectal abscesses Perianal 60% Ischiorectal 20% Intersphincteric 5% Supralevator 4% Submucosal 1%

Classification Perianal – pus underneath skin of anal canal, do not traverse external sphincter. Ischiorectal – suppuration traversing external sphincter into Ischiorectal space. Intersphincteric – suppuration between external and internal sphincter. Horse shoe abscess - uncommon circumferential infiltration of pus with in intersphincteric space.

Investigation & Imaging No specific test required Patients with diabetes , immunosuppresed will need lab evaluation. Imaging – role in only deep seated, Supralevator or intersphincteric abscesses. CT Scan , MRI or Anal ultrasonography.

Management Mainly surgical Antibiotics in diabetics & immunocompromised individuals. Early drainage is indicated as delay can cause- * prolong infection * tissue destruction ↑ * chances of sphincter dysfunction ↑ * Promote fistula formation.

Management Perianal abscess - superficial ones can be drained in office under L.A Incision Pus culture & sensitivity Packing with iodophor gauge. Laxative & Sitz bath. Review & follow up 2-3 weeks to see for healing & fistula formation.

Management Organism culture is important. Abscess with intestinal organisms have a 40% chance of forming fistula. Cultures growing Staphylococcus species –Perianal skin infection and have no risk of subsequent fistula formation. 2. Ischiorectal abscess - GA Cruciate incision over max swelling.

Management Pus drained and cultured Disrupt loculi Drain placed. 3. Intersphincteric abscess - Transverse incision in anal canal below the dentate line, posteriorly. Abscess opened, leave drain, prevents premature closure.

Management Supralevator abscess - Location & etiology determines its drainage technique. Evaluation with CT Scan & MRI . Abdominal pathology –deal with cause If extension of Ischiorectal –drainage through the space indicated. Anterior Supralevator are superficial and more common in females.- transanal or transvaginal approach can be used.

Anal fistula- “Fistula-in-ano” Definition - Hollow tract, lined with granulation tissue connecting a primary opening inside the anal canal to a secondary opening in the Perianal skin. Treatment of fistula-in-ano can be challenging.

Fistula-in-ano Magnitude of problem- Prevalence rate - 8.6 / 100,000 population. Male : Female = 2 : 1 Mean age = 38 Years.

Etiology * Following Anorectal abscess. * Other causes - Sec. to trauma - Crohn’s disease - Anal fissures - Carcinoma - Radiation therapy - Tuberculosis, Actinomycosis.

Pathophysiology

Clinical presentation History – Recurrent Swelling, Discharge, Pain and Surgery for an Abscess. Symptoms – - Perianal discharge - Pain - Swelling - Bleeding - External opening

Clinical presentation Past medical history- * Inflammatory bowel disease. * Diverticulitis * Previous pelvic radiation * Tuberculosis * Steroids therapy * HIV infection

Clinical presentations Physical examination - * Look at entire perineum, * An open sinus or elevation of granulation tissue. * Discharge may be seen. * DRE- fibrous cord, or cord beneath the skin. * Voluntary squeeze pressures & sphincter tone should be assessed.

Goodsall rule – Perianal fistula Transverse line drawn across the anal verge Anterior external opening associated with straight tract to anal canal or rectum. Posterior ext. opening follows curved tract, entering posterior midline. Exception 3cm

Park Classification system- Intersphincteric Transsphincteric Suprasphincteric Extrasphincteric

Fistula-in-ano Fistula with probe

Fistula-in-ano A. Intersphincteric - Via internal sphincter to intersphincteric space then to perineum. 70% B. Transsphincteric - Via internal and external sphincter into Ischiorectal fossa and then to perineum. 25%

Fistula-in-ano Transsphincteric fistula.

Fistula-in-ano C. Suprasphincteric – Via intersphincteric space superiorly to above puborectalis muscle into Ischiorectal fossa then perineum. 5% D. Extrasphincteric - From Perianal skin through levator ani muscles to the rectal wall completely outside sphincter mechanism. <1%

Imaging Studies Not indicated for routine evaluation Performed when external opening is difficult to identify, recurrent or multiple fistulae. Fistulography- - involves injection of contrast via the opening and taking images in different planes. - 15- 48% accuracy.

Imaging studies 2. Endo Anorectal Ultrasonography - - Transducer 7-10 MHz. - Installation of H2O2 can help location of internal opening . - not widely used. 3. MRI - - Study of choice - 80-90% concordance with oper.finding. - good for primary course and sec extensions.

Imaging 4. CT Scan – - Good for perirectal inflammation disease, delineating fluid pockets. - Needs oral and rectal contrast. - poor delineation of muscular anatomy. 5. Barium enema / Small bowel series - - Useful in multiple fistulae or recurrent disease, also to rule out IBD.

fistula imaging MRI showing intersphincteric fistula anteriorly Prm-puborectalis muscle.

Other investigations Anal Manometry- Pressure evaluation of sphincter mechanism help in some cases - - Decreased tone in preop evaluation - previous fistulectomy - obstetrical trauma - high transsphincteric or suprasphincteric fistula - very elderly patient. If decreased, avoid - surgical division of any portion of sphincter.

Diagnostic procedures A. E U A- Examination of perineum, DRE, anoscopy. To look for internal opening techniques- - Inject - H2O2, Milk, Dilute methylene blue - Traction on external opening may help - Probing gently can help. B. Proctosigmodoscopy / Colonoscopy- Rigid sigmoidoscopy to rule rectal disease.

Management 1. Fistulotomy / Fistulectomy - - laying open technique is useful in 85-95% of primary fistulae. - overlying skin, subcutaneous tissue, internal sphincter divided with electrocautry, curette tract to remove granulation tissue. - complete fistulectomy creates bigger wound with no advantage in minimizing recurrence. - perform biopsy of firm or suggestive tissue.

Management 2. Seton Placement – - Alone, in combination with fistulectomy or as a stage procedure- Useful in – Complex fistulae Recurrent fistulae after fistulectomy Anterior fistulae in females Poor preop sphincter pressure. Immunosuppresed patients.

Seton placement- Seton defines sphincter muscles Promotes - Drainage - Fibrosis. Material used- - Silk suture - Silastic vessel markers - Rubber bands

Seton Single stage (cutting) Passing seton through tract and tightened down with separate silk tie. Fibrosis above sphincter muscles seen as it cuts the muscles. Tightened in office over weeks 2. Two Stage (draining / fibrosis) Pass seton through deep portion of external sphincter. Seton left loose here. When superficial wound is healed , seton bound muscle is divided. Studies support 2 stage procedure using 0-nylon.

3.Mucosal Advancement Flap - In chronic high fistula , indication same as seton. Total fistulectomy , removal of primary and secondary tract with internal opening Rectal mucomuscular flap is raised . Internal muscle defect is closed with absorbable suture and flap is sewn down over internal opening. Single stage procedure Poor success in Acute infection and Crohn’s.

Follow up Sitz bath Analgesia Stool bulk agents (bran) Frequent office visits to ensure healing. Healing in 6 weeks.

Complications Early- Urinary retention Bleeding Fecal impaction Thrombosed hemorrhoids. Delayed - Recurrence Incontinence stool) Anal stenosis Delayed wound healing.

Outcome & Prognosis Following Rate of Recurrence Incontinence of stool Standard Fistulotomy 0 -18% 3 -7 % Seton 0 – 17% 0 -17 % Mucosal advancement flap 1- 10% 6 – 8%

Newer Developments Biotechnical advances are producing many new tissue adhesives. - some reports suggest 60% success with 1 year follow-up ,using fibrin glue in treatment of fistula-in-ano. - less invasive & ↓ postop morbidity.

Newer developments Recurrent fistulous disease to rectum and perineum with Anorectal sepsis – indication for surgery Recent reports suggest 50-60% response rate with infiximab - the monoclonal antibody to TNFα for Perianal fistulae.

Thank you