To diagnose trichomoniasis, a physician will compile a patient’s medical history and perform a complete physical examination. Female patients will undergo a pelvic examination, during which the physician will open the walls of the vagina and look for small red sores inside the vagina or on the cervix.

A sample of vaginal fluid will be obtained and examined under a microscope to determine the presence of parasites. Additional tests that may be performed include a vaginal culture or DNA test. Physicians frequently also perform tests for other sexually transmitted diseases (STDs) such as gonorrhea and chlamydia, which may accompany trichomoniasis. A Pap smear may be performed to look for changes in cervical surface tissues that are sometimes associated with a prolonged trichomoniasis infection.

Trichomoniasis is often more difficult to diagnose in male patients. Special culture techniques may be necessary to make a definitive diagnosis. Male sexual partners of females infected with trichomoniasis are often assumed to be infected as well.