By Gabrielle Gleeson-Solomon, CEO of Tota
Scientific Review by Dr Nick Parkinson, PhD
Understanding BV and why it might keep coming back.
58% of women treated for BV with the standard course of antibiotics have it again within a year.
That's a staggeringly high recurrence rate for a condition we've known about for decades. It suggests that while antibiotics can treat BV in the short term, and do work for some women, they don't always address the root cause and what's allowing it to come back.
This is why researchers are starting to look beyond individual bacteria which can cause BV and towards the vaginal microbiome as a whole.
How common is recurrent BV?
BV is the most common vaginal condition in women of reproductive age. Estimates vary depending on who’s being studied, but it’s generally reported to affect between 10 and 30% of women in countries like the UK, and the World Health Organisation puts the global figure at 23 to 29%.
Recurrent BV is usually defined as three or more episodes in a year. You'll also see it called chronic BV.
But that definition doesn’t always reflect how it feels in real life. For many women, even one or two episodes a year can feel like BV keeps coming back, especially if it means another course of treatment, disrupted plans or worrying about when it might happen again.
Whether you meet the medical definition or not, recurring BV can have a real impact on day-to-day life. And despite how common it is, researchers are still trying to understand why some women experience it again and again.
How doctors test for BV
Most BV diagnoses in the UK happen in one of two ways: either clinically, based on your symptoms and an examination, or by sending a vaginal swab to a laboratory to be examined under a microscope.
The microscope method is called Nugent scoring. A lab scientist stains the sample, counts the different bacterial shapes visible on the slide and scores it from 0 to 10. A low score suggests a healthy balance of bacteria, while a high score is consistent with BV.
This is a genuinely useful test and it’s been the standard for decades for good reason. It’s quick, inexpensive and it catches straightforward cases well. But It's designed to answer one specific question: does this sample look like BV or not? Often, that’s not the whole story.
Why your BV test results don't always match your symptoms
This is where many women get stuck. You have vaginal symptoms but your swab is normal, or the results come back inconclusive, leaving you with no explanation for why you still don't feel right. It's a surprisingly common situation and an incredibly frustrating one to be in.
There are a few reasons why this can happen.
-
10% of standard swabs fall into a grey area called "altered flora". This means the balance of bacteria doesn't look completely typical, but it doesn't clearly meet the criteria for BV either. This leaves both you and your doctor without a clear answer or obvious next steps.
-
Routine swab tests are designed to identify the bacteria linked to BV, rather than the wider vaginal microbiome. That means changes that could be contributing to your symptoms can go unnoticed and undiagnosed.
-
Not every vaginal symptom is caused by BV, thrush or trichomoniasis. Vaginal symptoms can also be caused by hormonal changes, skin conditions, irritation and other non-infectious causes, so a normal swab doesn't always mean nothing is wrong.
That's why some women are left with symptoms but no clear explanation, and why researchers are increasingly looking beyond traditional testing to understand the vaginal microbiome as a whole.
Why BV often comes back
Researchers have several theories about why BV often comes back after treatment. Three of the strongest are:
The bacteria don’t fully clear
Some BV-associated bacteria form a biofilm, a sticky protective layer that sits on the vaginal wall and shelters the bacteria inside it. One study took samples from women after they’d completed standard antibiotic treatment and found the biofilm was still there. Symptoms often improve because the number of bacteria falls, but some remain protected within the biofilm. And sadly those bacteria are lurking, waiting for a chance to come back and multiply.
The protective bacteria don’t come back
Antibiotics reduce the problematic bacteria, but they don’t restore Lactobacillus, the bacteria that keep the vagina slightly acidic and make it harder for disruptive bacteria to take hold. If Lactobacillus doesn't recover after treatment, BV-associated bacteria have an opportunity to grow again, increasing the risk of recurrence.
Something else may have been missed
Since standard swab tests are designed to look for a small number of conditions, if another imbalance or organism contributing to your symptoms wasn't identified, treating BV alone may not fully address the underlying problem.
These explanations all point to the same idea: recurrent BV isn't always about a single infection. Sometimes it's about what's happening across the wider vaginal microbiome.
If your BV keeps coming back
If your BV keeps coming back, knowing you have it again might not be that useful. A vaginal microbiome test can give you and your healthcare provider a fuller picture to explore, including whether protective Lactobacillus bacteria have recovered and what other organisms are present.
What you can do
If your BV keeps coming back, it's not a sign you're doing anything wrong. Recurrent BV is common and while there isn't a guaranteed way to prevent it, there are a few things supported by current evidence that may help reduce the risk of it returning:
-
Always finish your full course of treatment, even if your symptoms improve sooner.
-
Avoid douching and internal cleansing products, which can disrupt your vaginal microbiome.
-
Use condoms if sex seems to trigger your BV, and clean sex toys thoroughly between uses.
-
Wipe from front to back after using the toilet.
-
Change tampons, pads and menstrual cups regularly.
-
If you smoke, consider stopping, as smoking is linked to recurrent BV.
When BV keeps coming back, doing the same thing you did the last time isn’t always the full picture... Sometimes understanding your vaginal microbiome can add a missing piece that can help to understand why BV keeps coming back.
Sources
- Bradshaw CS, Morton AN, Hocking J, Garland SM, Morris MB, Moss LM, Horvath LB, Kuzevska I, Fairley CK. High recurrence rates of bacterial vaginosis over the course of 12 months after oral metronidazole therapy and factors associated with recurrence. J Infect Dis. 2006;193(11):1478-1486. PubMed: 16652274
- Bilardi JE, Walker S, Temple-Smith M, McNair R, Mooney-Somers J, Bellhouse C, et al. The burden of bacterial vaginosis: women's experience of the physical, emotional, sexual and social impact of living with recurrent bacterial vaginosis. PLoS One. 2013;8(9):e74378. PubMed: 24040236
- World Health Organization. Bacterial vaginosis. WHO Fact Sheets. WHO
- 2019. Molecular diagnosis of vaginitis: comparing quantitative PCR and microbiome profiling approaches to current microscopy scoring. J Clin Microbiol. 2019;57:e00300-19. ASM Journals
- Redelinghuys MJ, Geldenhuys J, Jung H, Kock MM. Bacterial vaginosis: current diagnostic avenues and future opportunities. Front Cell Infect Microbiol. 2020;10:354. Frontiers
- British Association for Sexual Health and HIV (BASHH) / UK Health Security Agency. Vaginal discharge: treatment guidance. GOV.UK. GOV.UK PDF
- Muzny CA, et al. Understanding and preventing recurring bacterial vaginosis: important considerations for clinicians. Sex Transm Dis. 2020;47(7):441-449. PubMed: 37581202
This article is for general information and does not replace medical advice. If you're experiencing new, severe, persistent or worsening symptoms, please speak to a GP or another qualified healthcare professional.
0 comments