BV is a mild infection of the vagina caused by an imbalance in the growth of the bacteria that normally populate the vagina - it is not known exactly why this imbalance in bacterial growth occurs. This condition used to be called Gardnerella vaginitis, because Gardnerella is a type of bacteria that sometimes causes the infection. We now know that overgrowth of other types of bacteria can also cause BV.
- Lactobacillus spp. is the most frequently isolated genus of bacteria found in the healthy vaginal flora - they play a role in maintaining the balance of the normal vaginal flora by producing hydrogen peroxide.
Unlike sexually transmitted infections:
- Infection results from bacteria that are normally found in the vagin a
- A woman does not get the infection from a sex partner - It is most common in sexually active women, but women who are not sexually active also can develop the condition.
Problems caused by BV - include premature labor, premature birth, infection of the amniotic fluid, and infection of the uterus after delivery. Screening for bacterial vaginosis and treatment if necessary during pregnancy can help prevent these complications.
It is important to first exclude other serious infections - since vaginal discharge is also a symptom of other more dangerous infections, such as gonorrhea and chlamydia.
Medical Diagnosis Tests and Criteria for BV
- 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.
- Whiff Test - 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.
- The Hay/Ison criteria :
• Grade 1 (Normal): Lactobacillus morphotypes predominate.
• Grade 2 (Intermediate): Mixed flora with some Lactobacilli present, but Gardnerella or Mobiluncus morphotypes also present.
• Grade 3 (Bacterial Vaginosis): Predominantly Gardnerella and/or Mobiluncus morphotypes. Few or absent Lactobacilli. Hay et al., 1994
- The Amsel criteria: At least three of the four criteria should be present for a confirmed diagnosis
1. Thin, white, yellow, homogeneous discharge
2. Clue cells on microscopy
3. pH of vaginal fluid >4.5
4. Release of a fishy odor on adding alkali—10% potassium hydroxide (KOH) solution.
For more in-depth information, please read this Bacterial Vaginosis article.
