What is the treatment for perianal abscess with fistula in ano?

Treatment of Perianal Abscess with Fistula in Ano

Surgical drainage of the abscess is the definitive treatment for perianal abscess with fistula in ano, with appropriate management of the fistula based on its anatomical characteristics. 1, 2

Initial Management

• Surgical approach with incision and drainage is the definitive treatment for all anorectal abscesses 1, 2
• Timing of surgery should be based on the presence and severity of sepsis; patients with sepsis, immunosuppression, diabetes, or diffuse cellulitis require emergent drainage 1
• In fit, immunocompetent patients with small perianal abscesses without systemic signs of sepsis, outpatient management can be considered 1
• The incision should be kept as close as possible to the anal verge to minimize the length of a potential fistula while providing adequate drainage 1

Management of Associated Fistula

• If a low fistula not involving sphincter muscle (subcutaneous fistula) is identified, fistulotomy can be performed at the time of abscess drainage 2
• For fistulas involving sphincter muscle, place a loose draining seton rather than performing immediate fistulotomy to prevent incontinence 2, 3
• Avoid probing to search for a fistula if one is not obvious, as this may cause iatrogenic complications 2
• Meta-analysis shows significant reduction in recurrence, persistent abscess/fistula, or need for repeat surgery when fistula is treated at the time of abscess drainage (RR=0.13,95% CI=0.07-0.24) 4

Antibiotic Therapy

• Antibiotics are not routinely indicated for adequately drained anorectal abscesses in immunocompetent patients 2
• Antibiotic administration is recommended in the presence of sepsis or for immunocompromised patients 2
• When indicated, empiric broad-spectrum antibiotic therapy should cover Gram-positive, Gram-negative, and anaerobic bacteria 2

Post-Procedure Care

• Clean the perianal area gently after each bowel movement using warm water without harsh soaps 3
• Sitz baths with warm water for 10-15 minutes, 2-3 times daily to keep the area clean and reduce inflammation 3
• For patients with setons in place, ensure the seton remains properly positioned to maintain drainage of the fistula tract 3
• High-fiber diet and adequate fluid intake to promote soft, regular bowel movements and prevent constipation 3

Follow-up Care

• Regular follow-up appointments are essential to monitor healing and determine appropriate timing for seton removal if placed 3
• Monitor for signs of recurrent abscess formation, which requires immediate medical attention 3
• For complex fistulas, a combination of drainage and medical therapy may be used as maintenance therapy 3

Special Considerations

• The risk of recurrence after drainage alone can be as high as 44%, emphasizing the need for complete and accurate drainage 1
• Imaging (MRI, CT, or endosonography) is not routinely required but should be considered in cases of atypical presentation, suspected occult supralevator abscesses, or perianal Crohn's disease 2
• For patients with Crohn's disease, ensure appropriate medical therapy is continued to control disease-related inflammation 3

Potential Complications

• Inadequate drainage, loculations, horseshoe-type abscess, and delayed time from disease onset to incision are risk factors for recurrence 1
• Trading radical surgery for conservative procedures (non-sphincter cutting) such as draining seton, fibrin sealant, anal fistula plug, or advancement flap results in more recurrence/persistence requiring repeated operations in many cases 5