What is the management plan for an intersphincteric abscess?

Management of Intersphincteric Abscess

Intersphincteric abscesses should be surgically drained into the rectal lumen, often requiring a limited internal sphincterotomy for adequate drainage and prevention of recurrence. 1

Diagnosis and Assessment

• Clinical presentation: Pain is the most common symptom, with varying degrees of swelling, cellulitis, and tenderness depending on the location
• Imaging:
  • MRI is the gold standard for assessing anorectal abscesses and associated fistula tracts 2
  • Endoanal ultrasound is highly effective for localizing intersphincteric abscesses 3
  • CT with IV contrast may be needed for deeper abscesses to assess location and extent 2

Surgical Management

Primary Treatment Approach

1. Surgical drainage is the definitive treatment for intersphincteric abscesses 1

   • Unlike perianal and ischioanal abscesses (which are drained through the skin), intersphincteric abscesses should be drained into the rectal lumen 1
   • A limited internal sphincterotomy is often required for adequate drainage 1

2. Timing of surgery depends on clinical condition:

   • Emergent drainage is indicated in patients with sepsis, immunosuppression, diabetes mellitus, or diffuse cellulitis 1
   • In the absence of these factors, surgical drainage should ideally be performed within 24 hours 1

Specific Techniques Based on Abscess Location

• Low intersphincteric abscesses: De-roofing of the abscess and division of the internal sphincter up to the level of the dentate line 3

• High intersphincteric abscesses (with extension into intermuscular planes):

  • Often require staged procedures 3
  • Temporary transanal mushroom catheter (de Pezzer catheter) placement is effective 3, 4
  • For abscesses with high upward extension to the puborectal muscle level, consider transanal advancement flap repair combined with drainage 5

• Alternative minimally invasive approach: Endoanal ultrasound-guided needle aspiration under anesthesia has been reported as a simple and safe method with good outcomes 6

Management of Associated Fistulas

• If an obvious fistula is identified during abscess drainage:
  • For low fistulas not involving sphincter muscle (subcutaneous): Perform fistulotomy at the time of drainage 1
  • For fistulas involving any sphincter muscle: Place a loose draining seton 1
  • Avoid probing to search for fistulas if not obvious, as this may cause iatrogenic complications 1, 2

Antibiotic Therapy

• Antibiotics are indicated in the following scenarios 1, 2:

  • Presence of sepsis or systemic infection
  • Surrounding soft tissue infection
  • Immunocompromised patient
  • Inadequate source control

• When indicated, use empiric broad-spectrum antibiotics covering Gram-positive, Gram-negative, and anaerobic bacteria 1, 2

  • Consider MRSA coverage as prevalence can be up to 35% in some locations 2
  • For immunocompetent patients with adequate source control: 4-day course
  • For immunocompromised patients: Up to 7-day course based on clinical condition 2

Post-Procedure Care and Follow-up

• Wound care:

  • Clean the wound with warm water/saline 2-3 times daily
  • Consider sitz baths for perianal region
  • Use non-adherent absorbent dressings 2

• Follow-up schedule:

  • First follow-up within 48-72 hours after drainage
  • Subsequent follow-ups every 1-2 weeks until complete healing
  • Monitor for signs of recurrent abscess, fistula development, delayed healing, or persistent infection 2

• For patients with seton placement:

  • Maintain seton for 1-2 months until resolution of induration and suppuration
  • Consider staged tightening of cutting setons in monthly intervals 2

Complications and Pitfalls

• Recurrence risk: Inadequate drainage, loculations, horseshoe-type abscess, and delayed time from disease onset to incision increase recurrence risk 1

• Fistula development: Up to one-third of perianal abscesses may manifest a fistula-in-ano, increasing the risk of abscess recurrence 1

• Sphincter damage: Excessive division of the internal anal sphincter carries a risk of fecal incontinence, particularly with high intersphincteric abscesses 3, 5

• Supralevator extension: Intersphincteric abscesses with supralevator extension are more challenging to treat and may require multiple procedures for complete healing 5