A comparative study of two methods of large loop excision of the transformation zone.

Objective: To determine whether the conventional large loop excision of the transformation zone (CLLETZ) and the "top-hat" technique (THLLETZ) differ in (a) completeness of excision of the cervical lesion, (b) depth of cervical tissue excised and (c) adequacy of follow up by cytology and colposcopy.

Design: Retrospective case review.

Setting: University Teaching Hospital, London.