Viruses sometimes cause mild lesions ( LSIL, low grade ) which often heal on their own (through immunity) and sometimes more serious lesions ( HSIL, high grade ) which require local treatment. Treatments are effective against these lesions but do not eliminate all viruses. There may therefore be recurrences (5 – 10%) after the treatments.

A biopsy (more details) is necessary before treatments . Lesions of uncertain origin (ASCUS) usually only require careful examination (colposcopy).