I believe my girlfriend might have one of the following. bacterial vaginosis, uti, yeast infection. what diagnostic tools are used to 100% decide this?

Proper evaluation: The clinician uses history (review of events), physical exam & whatever lab testing is considered relevant to the previous two factors. That could include a urinalysis & culture,a specimen of vaginal mucous examined in the lab or other tests as guided by the findings. An evaluation for other relevant conditions may also be necessary.Failure to detect & treat the right issue could make her sterile