The false negative rate of cervical smears in high risk HIV seropositive and seronegative women.

We undertook a prospective study of cytology and concurrent colposcopically directed biopsies of both Human Immunodeficiencey Virus seronegative (HIV-) and seropositive (HIV +) women at high risk for cervical intraepithelial neoplasia (CIN) to determine the accuracy of Pap smears in this population. Women were recruited from a sexually transmitted disease clinic and a women's prison in eastern Massachusetts. All were interviewed, blood was tested for HIV with CD4 counts done in 101 of the 102 HIV + women, and all received a pelvic exam that included a conventional Pap smear, a Thinprep test, and colposcopy with directed biopsies and endocervical curettage. A total of 184 women volunteered. 82 were HIV- and 102 were HIV+. The prevalence of CIN in HIV+ women was 37%, more than twice the 17% prevalence of CIN in HIV-women (P = 0.002). When Atypical Squamous Cells of Undetermined Significance (ASCUS) findings were included with "negative" cytology, the conventional Pap smear false negative rates for HIV- and HIV+ women were 21% and 37%, respectively. When ASCUS was included with "positive" cytology, the false negative rates dropped to 14.3% for HIV- women and 10.5% for HIV+ women. We conclude that ASCUS diagnoses comprised the majority of false negatives in HIV+ women.