Prognosis after simple incision and drainage for a first-episode acute pilonidal abscess.

During a 3-year period 73 patients were treated consecutively for a first-episode acute pilonidal abscess with simple incision and drainage under local anaesthesia. In all cases the treatment relieved symptoms and all patients returned to work immediately after treatment. Healing per primam occurred in 42 patients (58 per cent; 95 per cent confidence limits: 45-69) within 10 weeks after treatment. These patients had significantly fewer pits and lateral tracts compared with patients who developed excessive granulation tissue after incision and who required definitive surgical treatment later. Nine patients (21 per cent; 95 per cent confidence limits: 10-37) with healing per primam developed recurrence of their pilonidal disease during the prospective follow-up period (median follow-up period was 60 months, range 36-84 months). Actuarial analysis of the data revealed a constant cure rate of 76 per cent (95 per cent confidence limits: 57-95) after 18 months.