Post-treatment observation requires long-term monitoring, with most recurrent and persistent CIN seen 1-5 years after treatment, and cytology for persistent or recurrent CIN, combined with HPV and cytology testing. Colposcopy and cervical canal sampling are appropriate for cytologic ASCUS or higher cytologic findings, or for HPV-positive patients. If HPV negative, or two consecutive negative cytology tests, routine screening every 12 months is recommended and should be maintained for at least 20 years.