Laser Treatment of Cervical Intraepithelial Neoplasia and the Endocervical Button

A prospective randomized clinical trial was undertaken to investigate the relationship between the shape of cervical tissue vaporized with CO 2 laser and the postoperative location of the squamocolumnar junction. It has been suggested that a button of columnar epithelium may be everted onto the exocervix by vaporizing a shallow 1 mm trench around the endocervical canal after the evaporization cone has been completed. Eighty-eight patients with cervical intraepithelial neoplasia (CIN) suitable for treatment by CO 2 laser were randomized into two groups. The transformation zone was ablated to 6 mm in all patients. In the flat group (n = 45), the base of the cervical defect was flat. In the contour group (n = 43), an additional 1 mm trench was vaporized at the periphery of the defect. Both groups were similar with respect to age, use of oral contraceptives, parity, operative complications, degree of CIN, and volume of tissue ablated. On follow-up at 6 months, significantly more patients in the contour group had an endocervical button of columnar epithelium compared to the flat group. No difference was seen at 3 and 12 months. There was a moderate relationship between the volume of tissue vaporized and the area of the button in the contour groups (p less than 0.001) but not in the flat group. The presence of squamous metaplasia tends to increase with time. There were 2 recurrences of CIN at 1 year follow-up.