Biopsy site selection during colposcopy and distribution of cervical intraepithelial neoplasia.

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. chi 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.