CIN in pregnancy: antepartum and postpartum cytology and histology.

Objective: To determine the rates of antepartum and postpartum cervical intraepithelial neoplasia (CIN) 2 or worse in pregnant women with abnormal cervical cytology.

Study Design: A prospective, cohort study of 283 pregnant women referred for colposcopy between 1992 and 1999 for the evaluation of abnormal Pap smears. In this analysis, the population was stratified by severity of referral cytology (atypical squamous cells of undetermined significance [ASCUS] or low grade squamous intraepithelial lesion [LSIL] versus high grade squamous intraepithelial lesion [HSIL] and atypical glandular cells of undetermined significance [AGUS]).

Results: Sixty-seven women (24%) had ASCUS, 147 (52%) LSIL, 67 (24%) HSIL and 2 (0.7%) AGUS. As compared to women with HSIL or AGUS, women with ASCUS or LSIL were less likely to undergo antepartum biopsy (relative risk [RR] .34, 95% CI .23-.51) and if biopsied, less likely to have CIN 2 or worse (OR .49, 95% CI .24-.99). Women with antepartum ASCUS or LSIL were less likely to have postpartum HSIL (OR .29, 95% CI, .17-.52) and tended to have fewer histologically severe biopsies as compared to women with antepartum HSIL (OR .55, 95% CI .31-1.05).

Conclusion: Among those biopsied, pregnant women with mildly abnormal cytology (ASCUS or LSIL), as compared to pregnant women with HSIL, were less likely to have either antepartum or postpartum CIN 2 or worse.