Objective. To determine if sites selected for colposcopic biopsy and histologically proven cervical intraepithelial neoplasia are distributed randomly across the cervix.
Materials and Methods. Data were evaluated from all patients who visited the Walter Reed Army Medical Center Colposcopy Clinic during a 20-month period. χ2 analysis was performed to assess the randomness of distribution of biopsies and cervical intraepithelial neoplasia.
Results. In 303 patients, 479 biopsies were performed. The 11-, 12-, and 1-o'clock positions were selected for 190 of 479 (40%) of biopsies, whereas the 6- and 12-o'clock positions were chosen for 186 of 479 (39%) of biopsies (p < 0.0001). Of 479 specimens, 161 (34%) were diagnosed as low-grade and 57 (12%) were diagnosed as high-grade. The 6-, 11-, and 12-o'clock positions accounted for 32 of 57 (56%) high-grade biopsies (p < 0.0001). The 6- and 12-o'clock positions accounted for 61 of 161 (38%) low-grade biopsies (p < 0.0001).
Conclusions. Loci selected for biopsy and histologically confirmed cervical intraepithelial neoplasia are not randomly distributed across the cervix. There is a predilection for the locations anterior and posterior to the cervical os.