The further evaluation of patients whose Papanicolaou smears show atypical squamous cells of undetermined significance (ASCUS) or low-grade squamous intraepithelial lesions (SIL) remains controversial. Selecting the optimal management strategy is complicated because the incidence of high-grade dysplasia in these women varies. Kobelin and colleagues conducted a retrospective chart review to determine the clinical predictors of significant dysplasia in patients with minimally abnormal Pap smears.

The charts of more than 400 women referred for colposcopy because of Pap smears interpreted as showing ASCUS or low-grade SIL were reviewed. Exclusion criteria included women who were pregnant or in the post-partum period and those with a history of in utero exposure to diethylstilbesterol, lower genital tract dysplasia or human immunodeficiency virus infection. All colposcopic examinations were conducted by the same examiner, and all specimens were examined by the same team of pathologists.

The median age of the study participants was 30 years. Sixty percent of the women were nulliparous, 17 percent were smokers and 32 percent used oral contraceptives. No cases of invasive cervical cancer were diagnosed at colposcopy. A total of 137 women (34 percent) had either low-grade SIL or high-grade SIL. Colposcopy confirmed low-grade SIL in 47 of the 203 women (23.2 percent) with SIL on Pap smear. An additional 42 women with low-grade SIL on Pap smear (20.7 percent) had high-grade SIL at colposcopy. Of the 203 women with ASCUS on Pap smear, low-grade SIL was diagnosed by colposcopy in 31 (15.3 percent), and high-grade SIL was diagnosed by colposcopy in 17 (8.4 percent).

The strongest independent predictor of histologic high-grade SIL at colposcopy was age younger than 35 years. These women were 2.6 times more likely than women older than 35 years to have histologic high-grade SIL by colposcopy. The next strongest predictor was low-grade SIL on Pap smear and a history of condyloma. Patients with low-grade SIL on Pap smear were 2.5 times more likely to have histologic SIL at colposcopy than patients whose Pap smears were reported as ASCUS. The subgroup of women with ASCUS who were 35 years or older had the lowest incidence of SIL at colposcopy (14 percent). The subgroup of women younger than age 35 with low-grade SIL on Pap smear had the highest incidence of SIL (51 percent) and high-grade SIL (24 percent) at colposcopy.

The authors conclude that colposcopy should be considered for use in all women with minimally abnormal Pap smears because of the high prevalence of SIL. However, the optimal approach to management of these women remains unknown. The authors suggest that since age and histologic status of the Pap smear are predictive of dysplasia, these factors could be used to identify patients at particularly high risk of cervical dysplasia.