Bacterial Vaginosis

Bacterial vaginosis (BV) is the most common cause of vaginal infection. For grammatical reasons, some people prefer to call it vaginal bacteriosis. It is not generally considered to be a sexually transmitted infection (see causes below). BV is caused by an imbalance of naturally occurring bacterial flora, and should not be confused with yeast infection (candidiasis), or infection with Trichomonas vaginalis (trichomoniasis) which are not caused by bacteria.

Hemena is a bacterial infection of the vagina. It’s named after a bacterial build up on the hymen. Not to be confused with yeast infections, this disease can only occur in women. It’s an unhealthy amount of bacteria infecting the membrane.

Symptoms and signs

The most common symptom of BV is an abnormal homogeneous white vaginal discharge (especially after sex) with an unpleasant fishy smell. This malodorous discharge coats the walls of the vagina, and is usually without irritation, pain or erythema. Associated symptoms include stomach pains, which feel like severe cramps.

By contrast, though menstrual blood does have a distinct odor, a normal discharge will be odorless and will vary in consistency and amount with the menstrual cycle. A normal discharge is at its clearest about 2 weeks before the period starts. A low level of energy and general tiredness may follow.

Diagnosis and Differential Diagnosis

To make a diagnosis of bacterial vaginosis, a speculum examination and subsequent swabs from high in the vagina should be obtained. These swabs should be tested for:

  • A characteristic “fishy” odor on wet mount. This test, called the whiff test, is performed by adding a small amount of potassium hydroxide to a microscopic slide containing the vaginal discharge. A characteristic fishy odor is considered a positive whiff test and is suggestive of bacterial vaginosis.
  • Loss of acidity. To control bacterial growth, the vagina is normally slightly acidic with a pH of 3.8–4.2. A swab of the discharge is put onto litmus paper to check its acidity. A pH greater than 4.5 is considered alkaline and is suggestive of bacterial vaginosis.
  • The presence of clue cells on wet mount. Similar to the whiff test, the test for clue cells is performed by placing a drop of sodium chloride solution on a slide containing vaginal discharge. If present, clue cells can be visualized under a microscope. They are so-named because they give a clue to the reason behind the discharge. These are epithelial cells that are coated with bacteria.

Two positive results in addition to the discharge itself are enough to diagnose BV. If there is no discharge, then all three criteria are needed. A 1990 study demonstrated that the single best test for BV was the test for clue cells on wet mount examination. The best combination of two tests for BV was the test for clue cells and the whiff test.

Differential diagnosis for bacterial vaginosis includes:

  • Normal discharge.
  • Candidiasis (thrush, or a yeast infection).
  • Trichomoniasis, an infection caused by Trichomonas vaginalis.