What is bacterial vaginosis?
Bacterial vaginosis is a condition where there is an overgrowth of bacteria in the vagina. Normally, there are many “good” bacteria and some “bad” bacteria in the vagina. In bacterial vaginosis, the balance between good and bad bacteria is disrupted. The most common symptoms are an abnormal vaginal discharge that may have a fishy odor. However, some women have no symptoms at all. Bacterial vaginosis is not a sexually transmitted infection, but it does increase a woman’s risk of acquiring STIs.
Why test for bacterial vaginosis?
Here are some key reasons to test for bacterial vaginosis:
- To find the cause of vaginal symptoms like discharge, odor, pain, itching etc.
- To screen for bacterial vaginosis in pregnancy as it can lead to complications like preterm delivery
- To check if bacterial vaginosis is the cause of vaginal infections after procedures like abortions, IUD insertions etc.
- To screen women before gynecologic procedures or surgeries to lower the risk of postoperative infections
- To monitor the response to treatment when a woman has been diagnosed with bacterial vaginosis
- As part of an evaluation for infertility issues, pelvic pain or other chronic vaginal symptoms
Detecting and treating bacterial vaginosis when present can improve a woman’s gynecologic health and prevent complications.
Who should be tested for bacterial vaginosis?
The following women should be tested for bacterial vaginosis:
- Pregnant women during the first prenatal visit. Bacterial vaginosis increases the risk for preterm labor and other complications of pregnancy.
- Women undergoing a gynecologic procedure like abortion, hysteroscopy, IUD insertion etc. Testing allows antibiotic treatment if positive to lower infection risk.
- Women with symptoms like vaginal discharge, odor, burning urination, itching, soreness or irritation.
- Women diagnosed with a sexually transmitted infection. Bacterial vaginosis makes women more susceptible to STIs.
- Women going through infertility workup and treatments. Bacterial vaginosis can affect implantation and in vitro fertilization (IVF) success rates.
Screening for bacterial vaginosis may also be done in women:
- With vaginal dryness, pain or bleeding during sex
- Before starting birth control pills or hormone therapy
- Who have had multiple female partners
- Who douche frequently
- With HIV as bacterial vaginosis is associated with higher viral loads
- Who have had a hysterectomy or pelvic radiation
When should you get tested for bacterial vaginosis?
Here are some situations when testing for bacterial vaginosis is recommended:
- During pregnancy: All pregnant women should be tested early in pregnancy, even if they have no symptoms. Bacterial vaginosis can cause pregnancy complications.
- Before any gynecologic procedure: Women undergoing procedures like induced abortion, hysteroscopy, IUD insertion, hysterectomy, egg retrieval or tubal ligation should be tested. Treatment can reduce infection risk.
- If you have symptoms: Symptoms like abnormal vaginal discharge, odor, burning, irritation warrant testing.
- After unprotected sex: Testing allows treatment if positive, reducing the chance of other infections.
- Before starting birth control: Hormonal birth control can disrupt vaginal bacteria and lead to bacterial vaginosis in some women.
- During infertility evaluation: Bacterial vaginosis reduces fertility and IVF success rates.
- Before gynecologic surgery: Preoperative screening allows antibiotic treatment to lower surgical infection risk if bacterial vaginosis is detected.
- At routine medical visits: Screening may be done at your annual exam or Pap test. Testing is recommended at least once a year for women at high risk.
- Before starting estrogen therapy: Estrogen impacts vaginal bacteria. Testing allows treatment if bacterial vaginosis is present.
Women do not need to be tested for bacterial vaginosis if they have no symptoms or risk factors. Talk to your doctor about whether you need screening.
How is testing for bacterial vaginosis done?
There are two main ways to test for bacterial vaginosis:
1. Physical Exam
The doctor first takes a medical history and asks about symptoms. The physical exam involves:
- Inspecting the vagina for discharge – its amount, color, consistency and odor
- Testing vaginal pH using pH paper placed on vaginal discharge
- Adding a drop of potassium hydroxide (KOH) to discharge on a slide and checking for fishy odor
- Looking at discharge under a microscope (wet mount) to check for clue cells
Findings that suggest bacterial vaginosis include thin white or gray discharge, elevated pH, fishy odor with KOH test, and clue cells on the wet mount.
2. Lab Tests
- Gram stain: Vaginal discharge is applied to a slide, gram stained, and viewed under a microscope. The gram stain can detect clue cells and changes in vaginal bacteria.
- Culture: Collecting discharge with a swab and growing bacteria in a culture medium. This allows identification of the specific bacteria present.
- DNA probe testing: Swabs collect vaginal discharge, which is then tested for high levels of Gardnerella vaginalis bacteria using DNA probes.
- PCR test: This polymerase chain reaction test can precisely identify bacterial DNA in discharge samples.
Lab tests are more accurate in diagnosing bacterial vaginosis than the physical exam. However, they are also more expensive. Many doctors will do in-office testing first, followed by lab tests only if the diagnosis remains uncertain.
Interpreting test results
Bacterial vaginosis is usually diagnosed based on a combination of criteria, not just one test result.
- Thin gray or white vaginal discharge
- Fishy odor when potassium hydroxide is added to discharge
- pH of discharge above 4.5
- Clue cells visible on wet mount microscopy
- Positive whiff test detecting fishy odor
- Gram stain showing shift in vaginal bacteria
- Elevated levels of Gardnerella vaginalis or other anaerobes on culture
A positive DNA probe or PCR test for Gardnerella also confirms bacterial vaginosis.
A diagnosis of bacterial vaginosis typically requires at least 3 of the above criteria. How the diagnosis is made also depends on whether the woman has symptoms or not.
Women with symptoms
In women who have symptoms like odor and discharge, bacterial vaginosis can often be diagnosed in the medical office through a combination of pH testing, microscopy and the whiff test. Lab tests may only be needed if the diagnosis remains uncertain.
Women without symptoms
Women without vaginal symptoms require more accurate lab testing to diagnose bacterial vaginosis. This includes gram stain, DNA probe or PCR testing. Vaginal cultures may also be done.
False positive and false negative results
No test is perfect. False positive results can occasionally happen if another condition causes similar findings. Yeast infections, Trichomonas vaginalis and cervical infections can sometimes mimic bacterial vaginosis.
False negative results may occur if lab samples are not collected and processed properly. Insufficient discharge or cells will fail to detect bacterial vaginosis. Repeat testing is advised if negative results conflict with strong clinical evidence of the condition.
At-home testing
A few at-home tests for bacterial vaginosis are now available including:
- BVBlue test: This is a colorimetric test that mixes vaginal fluid with reagent drops. A resulting blue-green color indicates elevated pH and positive bacterial vaginosis.
- Pipette tests: These use a pipette to collect vaginal fluid. The sample is added to a testing card or cup which changes color if bacterial vaginosis is present. Examples are the BV Controll Test Kit, FemiClear and Luvena Prebiotic Plus BV Test.
- OSOM BVBlue: This Rapid Trichomonas Test can detect Gardnerella vaginalis antigens. About 30 minutes provides results.
Such tests are relatively inexpensive and convenient. However, they are not as accurate as lab testing. At-home tests may be useful for screening, but diagnosis still requires confirmatory clinical testing. Discuss home test results with your doctor.
Do I need to be tested again after treatment?
Yes, follow up testing is recommended after treatment for bacterial vaginosis. This allows your doctor to confirm:
- The antibiotics have worked effectively and the infection is cured
- The normal vaginal bacteria have been restored
- The risk of recurrence is lower
Retesting is typically done at the end of the treatment course or within 1-2 weeks. Lab tests like gram staining, DNA probes or cultures may be repeated.
Since bacterial vaginosis can recur, periodic screening is a good idea, especially if you are at high risk or pregnant. Discuss retesting frequency with your doctor. Some general guidelines include:
- Every 3-6 months in pregnant women
- Before gynecologic procedures or starting birth control or hormone therapy
- Whenever symptoms return
- Annually if you have HIV or multiple female partners
- Every 6-12 months if infertility is an issue
Early detection by retesting allows prompt retreatment and lowers complications. Inform partners and avoid douching or irritants to help prevent recurrence.
Can bacterial vaginosis be cured permanently?
Usually, bacterial vaginosis recurs after some time despite treatment. Very few women are cured permanently after a single course of antibiotics. Recurrence is common for several reasons:
- Antibiotics may not fully eradicate all the bacteria from the vagina and rectum.
- It is difficult to restore the normal balance between good and bad bacteria
- The vaginal environment encourages overgrowth of bacteria
- Sexual partners are often not treated, allowing reinfection
However, there are some steps you can take to achieve long-term cure and prevent recurrence:
- Seek care early as soon as you notice symptoms
- Take the full antibiotic course as prescribed
- Avoid irritants like douches, scented soaps, deodorant tampons
- Use only water and mild soap to gently wash the genital area
- Wear cotton underwear and avoid tight clothes
- Limit the number of sexual partners
- Ensure partners get treated simultaneously
- Consider probiotic supplements to restore healthy vaginal bacteria
- Request follow up testing after treatment
- Attend regular screenings as recommended by your doctor
While bacterial vaginosis keeps returning for many women, following these measures optimizes your chance for long term cure.
Takeaway
Here are some key takeaways about bacterial vaginosis testing:
- All pregnant women should be tested, even without symptoms
- Testing is recommended before gynecologic procedures and surgeries
- See your doctor if you notice foul vaginal odor or unusual discharge
- Screening can be done during annual exams for at-risk women
- Diagnosis requires a combination of clinical tests and lab cultures
- Get a follow up test after finishing treatment to confirm bacterial vaginosis is cured
- Consider periodic screenings as bacterial vaginosis often recurs
- Discuss appropriate testing frequency with your doctor based on individual risk factors
Detecting and treating bacterial vaginosis at the earliest is important to relieve symptoms, improve reproductive health, and avoid complications. Work with your doctor to determine if you need to be tested based on your medical history and risk factors. Testing allows timely treatment when bacterial vaginosis is found.
