Trichomoniasis can be diagnosed by looking at a sample of vaginal fluid for women or urine for men under a microscope. If the parasite can be seen under the microscope, no further tests are needed. If this test isn’t conclusive, tests called rapid antigen tests and nucleic acid amplification may be used.
https://www.mayoclinic.org/diseases-conditions/trichomoniasis/diagnosis-treatment/drc-20378613