Stepwise Diagnosis of Trichomonas vaginalis Infection in Adolescent Women

Abstract

ABSTRACT The objective of this study was to examine the effects of clinical factors and of the type and timing of a secondary test in improving the sensitivity of Trichomonas vaginalis detection in young women over that of a wet mount alone. For this purpose, sexually active adolescent women ( n = 345) were recruited from a hospital teen clinic or emergency department. Following an interview and a pelvic exam, four primary T. vaginalis tests (wet mount, culture, a rapid test, and a nucleic acid amplification test [NAAT]) were performed on vaginal swabs. If the wet-mount result was negative, two secondary tests (culture and a rapid test) were performed on the used wet-mount swab and saline. A positive result by any of the four primary tests was considered a true T. vaginalis -positive result. The prevalence of T. vaginalis was 18.8% overall and 8.8% in the 307 wet-mount-negative women. There was 100% concordance between primary and secondary rapid tests. Secondary culture was 80% sensitive compared to primary culture. The likelihood of a positive rapid test increased with increasing time between specimen collection and testing. A wet mount followed by a rapid test was the most sensitive strategy using two tests (86.4%; confidence interval [CI], 75.3 to 93.4%). Limiting secondary testing to those with multiple partners resulted in a lower sensitivity (73.9%; CI, 61.5 to 84%) that was not significantly better than that of the wet mount alone (58.5%; CI, 45.6 to 70.6%). We conclude that a rapid test can be delayed or performed on a used swab with no loss of sensitivity. Until a NAAT for T. vaginalis is commercially available, a stepwise approach using an additional rapid test for wet-mount-negative women is recommended for adolescent women regardless of clinical factors.