Cytologic predictors of cervical intraepithelial neoplasia in women with an ASCUS Pap smear.

To identify cytologic parameters on Pap smears of women with an atypical squamous cells of undetermined significance (ASCUS) diagnosis that could help cytologists to indicate whether a particular ASCUS case is most likely related to cervical intraepithelial neoplasia (CIN) grade 1 or 2/3.A total of 360 eligible women diagnosed with ASCUS and referred to the colposcopy clinic of Saint-Sacrement Hospital participated in the study. Eligible women were those aged 18-50 years, newly diagnosed with ASCUS, with no history of cervical biopsies or treatment, and not pregnant at the time of the visit. Colposcopically directed biopsies of lesions were obtained. All Pap smears were reviewed according to 36 different cytomorphologic criteria. The regression logistic model was used to estimate the odds ratios (ORs) for the associations between cytologic criteria observed in smears and the diagnosis of CIN made on biopsies. All cytologic criteria significantly (P < .05) associated with CIN were entered in the models, and a backward selection was done to determine independent cytologic predictors of CIN 1 and 2/3.Biopsies revealed that 22.2% of the study population had concurrent CIN. CIN I and 2/3 were identified in 61 (16.9%) and 19 women (5.3%), respectively. Clear perinuclear spaces (OR = 2.5, P = .002) and moderate nuclear atypia (OR = 4.4, P = .02) were two cytologic criteria independently associated with CIN 1. Four independent predictors of CIN 2/3 were identified: the presence of clear perinuclear spaces (OR = 5.9, P = .004), hyperchromasia (OR = 3.9, P = .04), moderate anisokaryosis (OR = 13.1, P = .01 and increased nuclear volume of metaplastic cells (OR = 5.1, P = .007).These observations may help cytologists to better categorize ASCUS lesions as intraepithelial ones and will also contribute to improving the Bethesda definition of ASCUS. Further studies are planned to validate these observations.