Pilonidal Abscess

A pilonidal abscess is acute infection of a pilonidal sinus producing a painful collection within the natal cleft.

The immediate problem is pus under pressure. Definitive sinus reconstruction can usually wait until acute inflammation has resolved.

There is acute sacrococcygeal pain with a tender fluctuant swelling.

The surrounding skin may be red and indurated.

Spontaneous rupture produces foul or purulent drainage and rapid reduction in pressure pain.

Diagnosis is clinical.

Imaging is unnecessary for a typical superficial abscess.

The definitive acute treatment is incision and drainage, including recurrent abscesses.

Use adequate local anaesthesia, evacuate pus and break down obvious loculations.

Antibiotics alone are inadequate.

Routine antibiotics after adequate drainage are unnecessary unless there is substantial cellulitis, immunosuppression or systemic infection.

A practical regimen when cellulitis requires therapy is:

Amoxicillin clavulanate 875 mg/125 mg orally every 12 hours for approximately 5 to 7 days.

Do not perform unnecessarily extensive excision through acutely inflamed tissue during routine abscess drainage.

After inflammation settles, reassess for persistent midline pits and chronic sinus disease. Many patients require subsequent definitive treatment, particularly after recurrent episodes.