Is outpatient incision and drainage (I&D) appropriate for a patient with a pilonidal abscess or should they be referred to a general surgeon?

Outpatient I&D for Pilonidal Abscess

For a pilonidal abscess in a fit, immunocompetent patient without systemic signs of sepsis, outpatient incision and drainage is appropriate and does not require referral to general surgery. 1

Patient Selection for Outpatient Management

You can safely manage this in the outpatient setting if the patient meets ALL of the following criteria:

• Young and fit with no significant comorbidities 1
• Immunocompetent (no immunosuppression, HIV, chemotherapy, or chronic steroids) 1, 2
• No diabetes mellitus (check serum glucose, HbA1c if not recently done) 1
• No systemic signs of sepsis (no fever, tachycardia, hypotension, or altered mental status) 1
• No extensive cellulitis or surrounding soft tissue infection 1
• No overlying skin necrosis or perforation 2

When to Refer to General Surgery

Refer immediately if ANY of the following are present:

• Sepsis, severe sepsis, or septic shock - requires emergent drainage in the OR 1
• Immunosuppression of any kind 1
• Diabetes mellitus (controlled or uncontrolled) 1
• Diffuse cellulitis extending beyond the immediate abscess area 1
• Complex anatomy (horseshoe abscess, suspected supralevator extension, or multiple loculations) 1, 3
• Suspected Crohn's disease (history of IBD, recurrent abscesses, or atypical presentation) 1, 3

Outpatient I&D Technique

For appropriate candidates, perform the following:

• Incision and drainage under local anesthesia is the primary treatment 1
• Keep the incision as close to the anal verge as possible to minimize potential fistula length while ensuring adequate drainage 1
• Complete drainage is essential - inadequate drainage leads to recurrence rates as high as 44% 1, 3
• Consider curettage of the cavity in addition to simple drainage, as this reduces recurrence from 42% to 11% and improves healing rates from 79% to 96% 4
• Unroofing and curettage can be performed as a single-stage definitive procedure in the outpatient setting with excellent results 5, 4

Alternative Approach for Selected Patients

Aspiration followed by antibiotics (cephalexin and metronidazole for 7 days) is effective in 83% of carefully selected patients and has high satisfaction rates, but this is less definitive than I&D with curettage 2

Post-Procedure Management

• No routine antibiotics are needed after adequate drainage unless there is surrounding cellulitis or the patient is immunocompromised 1
• Wound packing is controversial - evidence suggests it may be costly and painful without adding benefit, though this data is primarily from perianal abscesses 1, 3
• Daily warm sitz baths and local wound care 4
• Return to work in 7-10 days is typical 4
• Complete healing takes 4-10 weeks in most cases 5

Follow-Up and Recurrence

• Recurrence rates are 14-21% even with adequate initial drainage 5, 4
• Risk factors for recurrence include inadequate drainage, loculations, horseshoe-type abscess, and delayed treatment 1, 3
• Curettage at initial drainage reduces recurrence significantly compared to simple drainage alone 4
• Imaging is not routinely needed unless there is recurrence, suspected IBD, or non-healing wound 1, 3

Common Pitfalls to Avoid

• Do not probe for fistulas during acute abscess drainage - this causes iatrogenic complications 1
• Do not underestimate the extent - if you suspect complex anatomy or multiple loculations, refer to surgery 1, 3
• Do not perform simple drainage alone when curettage can be done safely - this significantly reduces recurrence 4