Mandatory screening to identify C. trachomatis recommended for pregnant women by the United States Centers for Disease Control and Prevention (CDC), the American College of Obstetrics and Gynecology and the US Public Health Center. Since traditionally, the use of urine samples to detect C. trachomatis is carried out in men and non-pregnant women, initially the researchers were not positive on the effectiveness of this method diagnosis in pregnant women.

Doubts have been associated, first of all, with the possible presence in pregnant women of urine of inhibitors of nucleic acid amplification in the urine, which can be the cause of false negative results and, by Therefore, lead to a decrease in the sensitivity of the method when using urine samples. However, the results of the study refuted these concerns.

A comparative analysis of the effectiveness of the two examination options was performed by a research team led by Dr. Scott Roberts of the University of Texas Southwestern Medical Center (Dallas, USA). During 4 months of 2018, women with a gestational age of 35 to 37 weeks, observed in family planning and obstetric complications clinics, were examined to identify C. trachomatis by the method of amplification of nucleic acids (Aptima Combo 2 Assay) using vagina and urine samples as material for the study of smears.

The average age of study participants was 26.9 years. In endocervical secretion smears and urine samples C. trachomatis was detected in 4.3% and 4.1% of cases, respectively. The sensitivity of the examination when using urine samples in relation to endocervical smears was 96.5% (95% confidence interval 90.1-99.3%), the relative specificity was 100% (95% CI 99.8-100%).

According to the researchers, a detailed analysis of the cost of each screening method is important in order to have a clear idea of the real reduction in costs by replacing the Pap test with urine samples.

The study authors in no way diminish the importance of having a vaginal exam which, in certain situations, is necessary. However, there is no question about the validity of taking any opportunity to do a urinalysis instead of taking a Pap smear. To date, in the clinics where the study was conducted, the method of amplifying nucleic acids using a urine sample to detect C. trachomatis is administered to all pregnant women.