Diagnosing human papillomavirus of the female lower genital tract: failure of the Pap smear as a sole screening test

Of 197 patients referred for colposcopy who underwent repeat Pap smears and colposcopic biopsies (when indicated), histologic evidence of human papillomavirus (HPV) infection involving the endocervix, cervix, or vagina or all three sites was documented in 109 biopsies. Sixty-six (61%) had normal Pap smears at the time of colposcopy. Despite a specificity of 92% for detecting HPV, the Pap smear demonstrated a low sensitivity (39%), with a positive and negative predictive test value of 88% and 50%, respectively. In patients with biopsies revealing HPV infection without associated dysplasia, false negative Pap smears were found most often in women with strictly vaginal HPV (74%) (P less than 0.05), followed by those with coexistent cervical and vaginal HPV (65%), and then by those with solely cervical HPV (51%). We question the use of the Pap smear for the detection of lower genital tract HPV, particularly in patients with only vaginal involvement, especially when the smear is repeated at the time of colposcopy. Benefits and disadvantages of other screening tests for HPV are discussed.