By Gabrielle Gleeson-Solomon, CEO of Tota
Scientific Review by Dr Nick Parkinson, PhD
On vaginal swab testing.
Being told your test is normal when you still have symptoms can be incredibly frustrating. You're left knowing something doesn't feel right, but without an explanation for why.
But you’re not alone. When researchers tested 290 women with vaginal symptoms, four in ten of them didn't have thrush, BV or trichomoniasis.
So why can a test leave you without an answer? In fact, why can multiple tests still leave you with no answers?
Here's what a standard swab covers, why symptoms can persist alongside a normal result, and what else might be worth considering.
What does a standard vaginal swab actually test for?
Most vaginal swabs in the UK are looking for a relatively short list of common conditions, including bacterial vaginosis (BV), thrush and trichomoniasis. Depending on your symptoms, your healthcare professional may also arrange separate tests for sexually transmitted infections such as chlamydia or gonorrhoea.
That approach exists for good reason. These are some of the most common causes of vaginal symptoms, and routine testing is quick, accessible and works well in straightforward cases. The current European guideline for vaginal discharge recommends this targeted approach as the starting point for investigating vaginal symptoms.
But that's also where the limitation comes in.
If your symptoms aren't being caused by one of those conditions, the test can tell you what you don't have. It can't always tell you the whole story or give you a detailed view of what is there.
Why can symptoms continue when your swab is normal?
There isn't one single explanation, but three things are worth understanding.
1. Not every vaginal symptom is caused by an infection
A swab is designed to detect infections.
But vaginal symptoms can also be caused by hormonal changes, skin conditions, irritation, inflammation and other non-infectious causes. If that's what's happening, the result may come back normal because the test has done exactly what it was designed to do.
A clear result doesn't mean your symptoms aren't real. It simply means the test didn't find an infection. That's one reason some women experience vaginal burning but no infection.
2. Your vaginal microbiome fluctuates
Your vagina isn't static.
Its bacterial community, known as the vaginal microbiome, naturally fluctuates throughout your menstrual cycle, during pregnancy, around menopause, after antibiotics, with different types of contraception and even following sex.
A swab captures what's happening on one particular day.
3. "Normal" doesn't always mean normal for you
This is perhaps the most important point.
Laboratories have to compare your sample against established reference criteria. That's essential for diagnosing any disease, but people aren't identical.
When researchers analysed the vaginal microbiomes of almost 400 healthy women, they found several different microbiome profiles among women with no symptoms at all. There wasn't one single version of a healthy vaginal microbiome.
That doesn't mean every microbiome is equally protective. We know that microbiomes dominated by Lactobacillus bacteria are generally associated with better vaginal health.
But it does remind us that biology is always more individual and more personal than a simple "normal" or "abnormal" result suggests.
Why scientists have started looking beyond routine swabs
Routine vaginal swabs have been an important part of diagnosing infections for decades, and they remain a valuable tool for identifying common conditions like BV, thrush and trichomoniasis.
But our understanding of the vaginal microbiome has changed dramatically over the last 20 years. Routine testing hasn’t caught up.
As DNA sequencing technology has improved, researchers have discovered many bacteria living in the vagina that couldn't be identified using traditional laboratory methods. They've also learnt that some vaginal symptoms aren't always caused by a single infection. Instead, they can be linked to changes across the wider bacterial community, known as the vaginal microbiome.
That means there's a strong argument that traditional testing methods no longer tell the whole story.
Traditional tests are excellent at finding the bacteria which cause conditions they were designed to detect. But many women continue to have symptoms because the cause sits outside that relatively short list of conditions. In some cases, it's simply something those tests were never developed to identify because they were developed before we knew many of these organisms and microbiome patterns even existed.
Rather than replacing what already exists, advances in DNA sequencing have given researchers another way to investigate what's happening when the answers aren't straightforward.
What can a vaginal microbiome test tell you?
If your symptoms continue despite a normal swab, it's worth asking whether the test looked for everything that could be causing them. A normal swab test typically confirms whether one particular condition is present or absent.
That's where looking at your vaginal microbiome can be helpful. Rather than checking for a handful of known organisms, a vaginal microbiome test identifies the bacteria and fungi present in your sample and shows how abundant they are. That creates a fuller picture to explore.
For women experiencing unusual discharge but tests are normal, vaginal burning but no infection, or other recurring vaginal imbalance symptoms, that extra information can sometimes give you and your healthcare professional more to explore, when routine testing hasn't provided an answer.
A vaginal microbiome test looks at more than a single suspected organism. Your results can show you:
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Which bacteria and fungi are present
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How much of each organism is there
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Whether protective Lactobacillus bacteria are dominant
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Whether your microbiome resembles patterns that researchers have associated with different vaginal conditions
It's important to say that no single test can explain every cause of vaginal symptoms. Hormonal changes, skin conditions and other medical conditions can all cause similar symptoms, which is why microbiome testing shouldn't replace medical advice.
But if you've been left wondering why your symptoms continue despite a normal swab, understanding your vaginal microbiome may provide another piece of the puzzle and give you and your healthcare professional more information to decide what to do next.
The bottom line
If you've been searching for vaginal symptoms but swab normal, the most important thing to remember is this:
A normal result doesn't necessarily mean nothing is happening. It means the test didn't find one of the specific conditions it was designed to look for.
If you’re still having symptoms but tests say everything is normal, it doesn't mean your symptoms aren't real, and it doesn't mean you have to simply accept not knowing what’s going on.
The understanding of the vaginal microbiome has advanced enormously over the last two decades, giving researchers and healthcare professionals new ways to investigate symptoms that previously couldn't be fully explained.
The more complete the picture, the better informed the decisions about what to do next can be. Understanding what's actually happening is the first step towards knowing what to do about it.
Sources
- Hillier SL, Austin M, Macio I, Meyn LA, Badway D, Beigi R. Diagnosis and treatment of vaginal discharge syndromes in community practice settings. Clin Infect Dis. 2021;72(9):1538-1543. PubMed: 32350529
- International Union against Sexually Transmitted Infections (IUSTI). 2023 IUSTI guideline for the management of vaginal discharge. IUSTI PDF
- Ravel J, Gajer P, Abdo Z, Schneider GM, Koenig SSK, McCulle SL, et al. Vaginal microbiome of reproductive-age women. Proc Natl Acad Sci U S A. 2011;108(Suppl 1):4680-4687. PNAS
- Fredricks DN, Fiedler TL, Marrazzo JM. Molecular identification of bacteria associated with bacterial vaginosis. N Engl J Med. 2005;353(18):1899-1911. NEJM
- Redelinghuys MJ, Geldenhuys J, Jung H, Kock MM. Bacterial vaginosis: current diagnostic avenues and future opportunities. Front Cell Infect Microbiol. 2020;10:354. Frontiers
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.
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