What is the management and treatment for a patient with a perirectal abscess?

Management of Perirectal Abscess

Surgical incision and drainage is the cornerstone of treatment for all perirectal abscesses and should be performed promptly to prevent complications. 1

Diagnosis and Assessment

• A focused medical history and complete physical examination, including digital rectal examination, are usually sufficient to diagnose perirectal abscesses 2
• Check for undetected diabetes mellitus by measuring serum glucose, hemoglobin A1c, and urine ketones, as diabetes is a common comorbidity 2, 3
• For patients with signs of systemic infection or sepsis, obtain complete blood count, serum creatinine, and inflammatory markers (C-reactive protein, procalcitonin) 2, 3
• Imaging is not routinely required but should be considered in cases of: 2, 1
  • Atypical presentation
  • Suspected occult supralevator abscesses
  • Suspected complex anal fistula
  • Suspicion of Crohn's disease
• When imaging is needed, CT scan offers advantages of short acquisition time and widespread availability, though MRI provides better soft tissue resolution 2, 4

Surgical Management

• Timing of surgery should be based on the presence and severity of sepsis: 2, 1
  • Emergency drainage for patients with sepsis, severe sepsis, or septic shock
  • Emergency drainage for immunosuppressed patients, diabetics, or those with diffuse cellulitis
  • In stable patients without these factors, surgical drainage within 24 hours
• The incision should be kept as close as possible to the anal verge to minimize potential fistula length 1
• Complete drainage is essential, as inadequate drainage is associated with high recurrence rates (7.6% of cases require reoperation within 10 days) 5
• Specific management based on abscess location: 1
  • Perianal and ischioanal abscesses: drainage via overlying skin
  • Intersphincteric abscesses: drainage via rectal lumen
  • Supralevator abscesses: drainage via rectal lumen or externally via skin

Management of Associated Fistulas

• If a low fistula not involving sphincter muscle (subcutaneous fistula) is identified, perform fistulotomy at the time of abscess drainage 2, 3
• For fistulas involving any 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, 3

Antibiotic Therapy

• Antibiotics are not routinely indicated after adequate surgical drainage in immunocompetent patients 1, 3
• Consider antibiotics only in cases of: 2, 1
  • Sepsis and/or surrounding soft tissue infection
  • Immunocompromised patients
  • When indicated, empiric therapy should cover Gram-positive, Gram-negative, and anaerobic bacteria

Special Considerations

• Horseshoe abscesses have a particularly high rate (50%) of operative failures and require special attention 5
• Patients with Crohn's disease require careful evaluation as approximately one-third of Crohn's patients will develop anorectal abscesses 2, 6
• Risk factors for complications and readmission include: 7
  • Morbid obesity
  • Preoperative sepsis
  • Dependent functional status
  • Female sex
  • Steroid/immunosuppression use

Post-Procedure Care

• The role of wound packing after abscess drainage remains controversial with insufficient evidence to make definitive recommendations 2, 3
• Consider follow-up imaging in cases of recurrence, suspected inflammatory bowel disease, or evidence of non-healing wound 1