How do you know (at home) if you have trichomoniasis vs. bacterial vaginitis?

You don't: As a med student, many thought they could tell by the odor, but the way to be sure includes an exam with testing.

Test: There are swabs taken from the vaginal discharge that chemically can distinguish whether the discharge comes from BV or trichomonas or both. One can also tell from looking at a smear on a glass slide under the microscope, whether the discharge comes from either one or both. At home there is no reliable way to tell. Neither infection does harm to a woman's body if she is not pregnant.