Introduction and objective: Trichomonas vaginalis, a flagellate’s pathogen protozoon, that is the cause of most common types of vaginitis may serve as a cofactor in HIV, associated with adverse pregnancy outcomes and predispose pregnant women to premature rupture ofmembranes and early labour. The prevalence range of disease is from 5% to more than 50% in different populations. In this study, we documented the prevalence of it in the enrolled population and determined the frequency distribution of trichomoniasis in health centers of Ardakan, Meibod, Yazd cities, and evaluation of diagnosis methods in 2006-2008.

Materials and methods: A total of 551 pregnant women were studied in health centers of Ardakan, Meibod and Yazd cities. Two sterile swabs were used to collect vaginal samples from each subject. The first one was used for making smear for Giemsa staining method and the second swab was specifically meant for culture. For obtaining some demographic information about the age, gender and marital status of the patients, structured questionnaires were administered to all the subjects examined, while in depth interviews were conducted on some subjects where questionnaires were not helpful. Data obtained were analyzed statistically by using chi-squared test (c2) and students' T-test. 

Results: Of 270 subjects studied in Ardakan, 16 cases (5.9%) had infection. In addition, of 181 subjects studied in Meibod, nine cases (5%), showed infection, and of 100 subjects studied in Yazd, two cases (2%) had infection. Clinically, 307 cases out of 551 subjects (55.7%) lacked any type of clinical symptoms. The rest of the patients showed clinical demonstration of whom 244 cases (44.3%) had vaginal discharge. There was no statistically significant correlation between trichomoniasis and factors such as gender, level of literacy, and number of pregnancies (P value=0.05). Most of the subjects belonged to the age group 21-25 year, this being consistent with more sexual activity. In addition all of the studied cases were at pregnancy age that, the incidence of infection is naturally insignificant for those at the middle years of pregnancy age range.

Conclusion: Mere microscopic diagnosis should be avoided since inexperienced pathologists readily mistake white or colorless vaginal discharge for semen. Additionally, obstetricians and midwives should instruct their patients in this regard and notify the sexuality transmitted disease pathogens to medical lab personnel.