Management of 4 cm Pilonidal Abscess
For a 4 cm pilonidal abscess, incision and drainage is the primary treatment, with antibiotics (cephalexin plus metronidazole for 7 days) recommended only if systemic signs of infection, extensive surrounding cellulitis, or immunocompromise are present. 1
Primary Treatment Approach
Incision and drainage is the definitive first-line treatment for acute pilonidal abscess, regardless of size 1. The surgical approach should include:
- Curettage of the abscess cavity is superior to simple drainage alone, with healing rates of 96% versus 78.7% for drainage alone 1, 2
- Avoid immediate primary closure during acute drainage, as this is associated with a 14% recurrence rate compared to secondary healing 1, 3
- All surgical wounds should be laid open with daily warm sitz baths recommended postoperatively 2
Antibiotic Indications
Antibiotics are NOT routinely necessary for simple pilonidal abscesses after adequate drainage in immunocompetent patients without systemic signs 1. However, antibiotics ARE indicated when:
- Systemic signs of infection are present (fever, tachycardia, hypotension) 1
- Extensive cellulitis surrounds the abscess 1
- Patient is immunocompromised 1
- Source control is incomplete 4
Antibiotic Regimen
When antibiotics are indicated, empirical coverage should target both aerobic and anaerobic pathogens 1:
- Cephalexin PLUS metronidazole for 7 days is the recommended regimen 1, 5
- Alternative: Amoxicillin-clavulanate (provides both aerobic and anaerobic coverage) 6
The rationale for dual coverage is that pilonidal abscesses harbor mixed flora including skin flora, anaerobes (Prevotella, Peptostreptococcus), and occasionally Actinomyces species 6.
Alternative Approach for Selected Patients
Aspiration followed by antibiotics may be considered in highly selected patients without diabetes, immunosuppression, overlying skin necrosis, or perforation 5:
- Success rate of 83% with aspiration plus cephalexin and metronidazole for 7 days 5
- High patient satisfaction (median VAS score 9/10) 5
- Only 10% required subsequent incision and drainage 5
Definitive Management
After resolution of acute inflammation (8-14 days), plan elective excision of the pilonidal sinus 1:
- Recommended delay is approximately 9 weeks after initial drainage 1
- Excision with Limberg flap technique has the lowest recurrence rate (2.6%) and acceptable complication rate (10.4%) 1
- This staged approach prevents the high recurrence rates (up to 42%) associated with drainage alone 2
Common Pitfalls
- Do not perform primary closure during acute abscess drainage—this increases recurrence to 14% 1, 3
- Do not rely on antibiotics alone without drainage—source control is mandatory 4
- Do not forget to plan definitive excision—simple drainage has a 40% recurrence rate without subsequent definitive surgery 2