Trichomoniasis is the most common non-viral sexually transmitted infection (STI) globally, caused by the microscopic parasite Trichomonas vaginalis. This single-celled organism primarily infects the genital area, typically the urethra in men and the vagina in women. The infection is often silent, with approximately 80% of infected individuals showing no symptoms, allowing the parasite to be unknowingly transmitted. Untreated trichomoniasis can increase the risk of acquiring or transmitting other STIs, including HIV. Laboratory testing is therefore an important step for diagnosis and public health.
Collecting the Necessary Samples
The initial step in laboratory testing is obtaining a suitable sample that is likely to contain the Trichomonas vaginalis parasite. The type of sample collected depends on the individual’s anatomy and the specific test method used. For women, a vaginal or endocervical swab is the most common and preferred method, collecting fluid from the lower genital tract.
In men, the parasite is usually found in the urethra, so a first-catch urine sample is frequently used. This involves collecting the initial urine stream, which contains cells and discharge from the urethra. A urethral swab may also be collected. Patients are often instructed not to urinate for at least one hour before sample collection to ensure a concentrated specimen.
The Different Laboratory Analysis Techniques
Once a sample is collected, it is analyzed using one of several laboratory methods. The traditional and quickest method is microscopy, often called a wet mount. This technique involves placing the fresh sample on a slide with saline solution and immediately examining it under a microscope to look for the parasite’s characteristic jerky, motile movement. While inexpensive and providing results in minutes, wet mount has a low sensitivity, often missing infections, especially in men or when the parasite load is low.
Another, more sensitive method is culturing, where the sample is introduced into a specialized medium designed to encourage the parasite’s growth. If the parasite is present, it multiplies. Culture is a highly sensitive method for women, but it is slow, requiring the sample to be incubated and checked over several days, sometimes up to seven.
The most accurate diagnostic approach available today is the Nucleic Acid Amplification Test, or NAAT. NAATs detect and amplify the parasite’s specific genetic material, its DNA or RNA, rather than relying on finding a live parasite. This molecular technique offers the highest sensitivity and specificity, allowing for reliable detection even when very few organisms are present. NAATs can be performed on various sample types, including vaginal swabs and urine, and can often be used for simultaneous testing of other STIs.
Understanding the Results and Timing
Test results for trichomoniasis are typically reported as either positive or negative, indicating the presence or absence of the Trichomonas vaginalis parasite. A positive result confirms an infection and indicates that antibiotic treatment is necessary. A negative result suggests the parasite was not detected, but a negative wet mount may sometimes lead to follow-up testing with a more accurate NAAT if symptoms persist.
The wait time for results is linked to the analysis technique used. A wet mount provides results at the point of care, often within 10 to 15 minutes. For culture, results can take between three to seven days as the organism needs time to grow. NAAT results are usually processed faster than culture, with most laboratories providing the outcome within one to three days. Once a diagnosis is confirmed, effective antibiotic treatment can be started to prevent its spread to sexual partners.