[Is the Papanicolaou smear useful as aid for diagnosing some sexually transmitted infections?]

We undertook this study to assess the validity of cytologic diagnosis of sexually transmitted infections like: bacterial vaginosis (BV), tricomoniasis and candidiasis using the Papanicolaou (Pap) smear.

Prospective, descriptive transverse study.

The present study was carried out in the Health Center Dr. José Castro Villagrana in Tlalpan, México, D.F. from January 1997, to February 2000.

Routine Pap smears and vaginal secretion smears were collected from two hundred and seventy one patients ranged from age 16-66 years, with cervicovaginitis diagnosis.

Of the 271 patients, 92 (33.9%) had bacterial vaginosis diagnosed by Amsel criteria, 47 (17.3%) had candidiasis by culture and 5 (1.8%) had tricomoniasis by wet smear. The Bethesda system for diagnosing BV on Pap smear had 66% sensitivity and a specificity of 86%. The respective positive predictive and negative predictive value were 79% and 84%. Therefore, compared to the Candida culture, cervical cytologic test results had a sensitivity of 21% and specificity of 99%. The predictive positive predictive and negative predictive values were 90% and 85%.

Specificity tended to be higher than sensitivity, in other words cytology tended to be more efficient in identifying women without sexually transmitted infection than in identifying those with infection. In summary, the Pap smear should not be used in lieu of more effective diagnostic test for sexually transmitted disease, and treatment should not be based on cytologic findings alone.