When a woman reports an unusual vaginal discharge, the doctor will ask her a series of routine questions to help distinguish mild from more serious conditions. Additional issues that might indicate the presence of a more serious condition include fever, pelvic pain, new or multiple sexual partners (especially with unprotected intercourse), and a history of sexually-transmitted infections.
In addition to these questions, the doctor will perform a pelvic exam. During the exam, the doctor notes the appearance of the vaginal lining and cervix. The doctor will also perform a manual exam of the ovaries and uterus. The cervix is examined for tenderness, which might indicate a more serious infection. The doctor may collect samples to check for chlamydia or gonorrhea infection.
Examining the vaginal discharge under the microscope can help distinguish bacterial vaginosis from yeast vaginitis (candidiasis) and trichomonas (a type of sexually transmitted infection). A sign of bacterial vaginosis under the microscope is an unusual vaginal cell called a clue cell. Clue cells are believed to be the most reliable diagnostic sign of bacterial vaginosis. In addition to clue cells, women with bacterial vaginosis have fewer of the normal vaginal bacteria, called lactobacilli. A vaginal pH greater than 4.5 is also suggestive of bacterial vaginosis.
Finally, the doctor may perform a "whiff test" with potassium hydroxide (KOH) liquid. When a drop of KOH testing liquid used in the "whiff test" contacts a drop of the discharge from a woman with bacterial vaginosis, a certain fishy odor can result.
