Objective: To determine the distribution of cervical intraepithelial neoplasia 2 or 3 on the uterine cervix.
Materials and methods: During two screening studies, 5,060 women underwent colposcopy with biopsy. If a cervical quadrant had no lesion, a random biopsy at the squamocolumnar junction was obtained.
Results: Cervical intraepithelial neoplasia 2 or worse was more common on the posterior (426/806; 52.9%) than on the anterior (380/806; 47.2%) cervix (p < .05) and was equally likely on the right (411/806; 51.0%) and left (395/806; 49.0%) sides of the cervix. More quadrants with colposcopically detected lesions of human papillomavirus or worse came from the anterior (1,338; 57.5%) than posterior (991; 42.6%) cervix (p < .05), whereas similar numbers of these lesions were found on the left (1,163) and right (1,166) sides of the cervix.
Conclusions: Cervical intraepithelial neoplasia 2 or worse is slightly more common on the posterior cervix. Using colposcopically detected lesions as a surrogate for cervical intraepithelial neoplasia 2 or worse inflates the prevalence of cervical intraepithelial neoplasia on the anterior cervix.