Smooth Muscle Actin Immunostain is Useful for the Diagnosis of Trichomonas Vaginalis in Vaginal Smears

Objective The parasite Trichomonas vaginalis (T. vaginalis) causes one of the most common non-viral sexually transmitted infections in humans. T. vaginalis is notorious for its inconspicuous appearance in vaginal smears. It can be missed under the microscope. Method In the present study, we investigate the immunoreactivity of T. vaginalis to smooth muscle actin (SMA) in the vaginal smear. Result T. vaginalis trophozoite and pseduocyst are immunoreactive for SMA in all of the study group cases (n = 21) and in none of the control group cases (n = 21). Thus, SMA immunostain is a sensitive method for the demonstration of T. vaginalis. Moreover, the protozoan attains a conspicuous and unique appearance. By SMA immunohistochemical stain, the apperance of T. vaginalis floated freely or located in the cytoplasm of the epithelial cells is easily identified. Conclusion We recommend performing SMA immunostain in every vaginal smear with clinical or pathologic suspicion of trichomoniasis.