Objective: To analyze the incidence of negative cone biopsies and evaluate the significance of the findings.
Study design: The study population consisted of women who underwent cervical conization at a university teaching hospital from February 1996 to December 2001. Three modalities were used for conization: CO2 laser, large loop excision of the transformation zone and needle excision of the transformation zone. Negative cones were defined as those not showing evidence of human papillomavirus infection, intraepithelial neoplasia of squamous or glandular origin, or invasive disease.
Results: During the study period, 817 conizations were performed. Of these, 206 (25%) were negative. Less than half the patients (41.7%) had a punch biopsy that matched the subsequent cone biopsy specimen. The negative cone rate in women with a punch biopsy showing cervical intraepithelial neoplasia (CIN) 1 was 60% in contrast with those who had a biopsy indicating CIN 2-3; the latter percentage was 16.5%, and the difference was statistically significant.
Conclusion: Close adherence to international guidelines during workup of an abnormal smear, meticulous colposcopy performed by a certified colposcopist and careful evaluation of punch biopsies by pathologists might help to decrease the negative cone rate.