Hot-knife conization of the cervix: clinical and pathologic findings from a study introducing a new technique.

Objective: To introduce an alternative method for conization of the cervix using a Teflon-coated hot knife and to evaluate thermal distortion, adequacy of excision, operating time, blood loss, and short- and long-term effects of this method.

Methods: Between 1987-1993, 88 patients underwent cervical conization using a Teflon-coated hot knife at temperatures ranging from 110-130C. Histopathologic slides were reviewed simultaneously by two pathologists, who assessed thermal distortion, adequacy of excision, and interpretability of the surgical margins. Clinical information was obtained prospectively, including operating time, blood loss, and depth and volume of the excised cone. In addition, data were accumulated retrospectively from 40 randomly selected patients who underwent cold-knife conization between 1985-1990. Short- and long-term data were assessed for healing and scarring and the adequacy of postoperative Papanicolaou smears in the hot-knife patients.

Results: Thermal injury was minimal, with 300 mu or less in 83 patients (92%) and 350-600 mu in four patients. One patient had thermal distortion of 1500 mu. All slides were interpreted adequately. Blood loss was mild to moderate in 84 of 88 patients (95%) in the hot-knife group and in 34 of 40 patients (85%) in the cold-knife group. No patient in the hot-knife group needed blood transfusion or hospitalization. Operating time was reduced by as much as 67% when the hot knife was used. Thirteen percent of the hot-knife patients developed stenosis of the external os. No patient in the hot-knife group developed recurrence within 2 years of surgery.

Conclusion: Using a Teflon-coated hot knife for conization of the cervix produces adequate surgical margins and reduces blood loss and operating time over that with cold-knife conization. Long-term follow-up reveals no increase in cervical stenosis and demonstrates adequate cytologic smears in the hot-knife patients.