Can a Saliva Test Help Diagnose Endometriosis?

Endometriosis has historically been a difficult condition to diagnose, with the average wait time now reaching 9 years in the UK. A newer endometriosis saliva test, Ziwig Endotest®, is now available through My Atlas as an additional diagnostic option for women with symptoms suggestive of the condition.

For some women, symptoms are severe and persistent. For others, they may be intermittent, overlap with gastrointestinal or urinary symptoms, or initially be attributed to something completely different.

Investigations may include clinical assessment, ultrasound, MRI and, in some circumstances, laparoscopy.

Ziwig Endotest® uses a saliva sample to analyse a molecular signature associated with endometriosis.

So, how does an endometriosis saliva test work - and where could it fit within the wider diagnostic process?

Holly Devine

28 Sep 2026

Endometriosis saliva test Ziwig Endotest for women with suspected endometriosis

Quick Facts

Sample: Saliva
Age: 18–43 years
Technology: Salivary microRNA analysis
Method: Next-generation sequencing + artificial intelligence
Result: Positive or negative
Blood draw required: No
Can be performed during hormonal treatment: Yes
Can be performed throughout the menstrual cycle: Yes
Medical authorisation required: Yes
Endotest® is an in-vitro diagnostic medical device used on medical prescription for women aged 18–43 with symptoms suggestive of endometriosis.

What is Endometriosis?

Endometriosis is a condition where tissue similar to the lining of the uterus is found elsewhere in the body.

It commonly affects structures within the pelvis, but the symptoms and location of disease can vary considerably.

Symptoms associated with endometriosis can include:

Painful periods
Persistent or recurrent pelvic pain
Pain during or after sex
Pain during bowel movements
Pain when urinating
Cyclical bowel or bladder symptoms
Rectal bleeding or blood in the urine associated with menstruation
Difficulty conceiving
Pain extending into other areas, including the shoulder in some presentations

Importantly, the severity of someone’s symptoms does not necessarily tell us the location or extent of their endometriosis.

Why can diagnosing endometriosis be difficult?

Endometriosis diagnosis in the UK can involve a combination of symptom assessment, ultrasound, specialist imaging and, in some cases, laparoscopy.

There isn’t one symptom that identifies endometriosis.

Pelvic pain, changes in bowel habits, painful periods, urinary symptoms and fatigue can overlap with several other conditions.

Imaging also isn’t perfect.

Current NICE guidance recommends trans-vaginal ultrasound for people with suspected endometriosis, but specifically advises clinicians not to rule out endometriosis simply because an examination or ultrasound is normal.

Specialist ultrasound, MRI or laparoscopy may subsequently be considered depending on the individual case.

This is one reason there is growing interest in biological tests capable of providing additional information during the diagnostic pathway.

What is Ziwig Endotest®?

Ziwig Endotest® is different from a hormone blood test.

It doesn’t measure oestrogen, progesterone or other reproductive hormone concentrations.

Instead, it looks for a specific pattern of microRNAs within saliva.

MicroRNAs – often shortened to miRNAs – are small RNA molecules involved in regulating gene expression, essentially tiny molecules that help control how your genes are switched on and off.

Researchers have found that patterns of these molecules can contain information associated with different biological and disease processes.

Endotest® uses this information to identify a molecular signature associated with endometriosis.

How does the endometriosis saliva test work?

The process begins with a specialist saliva sample.

In the laboratory, the microRNAs present within the sample are analysed using next-generation sequencing, often abbreviated to NGS.

This produces a large amount of molecular data.

Artificial intelligence is then used to analyse the resulting microRNA profile and identify whether the pattern associated with endometriosis is present.

The laboratory result is reported as either:

Positive

Negative

Ziwig describes the technology as combining high-throughput salivary microRNA sequencing with artificial-intelligence analysis.

How accurate is Ziwig Endotest®?

This is where clinical context matters.

Ziwig reports validation performance of:

Sensitivity: greater than 97%
Specificity: greater than 93%

within the clinical validation data it references.

Sensitivity broadly describes how effectively a test identifies people who have the condition, while specificity relates to correctly identifying those who do not.

However, diagnostic performance should always be interpreted within the population in which a test has been studied.

A test result should therefore never replace the wider clinical picture.

Does Endotest® replace an ultrasound or MRI?

No.

With the wait times continuously growing for gynaecology referrals within the UK healthcare system – this is an important distinction.

An Endotest® result can provide information about whether the molecular signature associated with endometriosis has been detected.

It cannot show:

Where lesions are located
How large lesions are
Whether deep endometriosis is present
Which organs may be affected
The anatomical extent of disease
Imaging therefore has a different job.

NICE currently recommends ultrasound as part of the investigation of suspected endometriosis, with specialist ultrasound or MRI considered when deep endometriosis is suspected.

Think of these investigations as providing different pieces of information rather than competing with one another.

What if my ultrasound was normal?

A normal ultrasound does not necessarily mean your symptoms should simply be dismissed.

NICE specifically states that the possibility of endometriosis should not be excluded purely because pelvic examination and ultrasound are normal.

Where symptoms remain persistent or significantly affect daily life, further assessment or referral may still be appropriate.

This is also one of the situations in which additional diagnostic information may be particularly useful.

Who is Ziwig Endotest® suitable for?

The current intended population is women aged 18–43 years with symptoms suggestive of endometriosis.

Potential symptoms include:

Chronic pelvic pain
Painful periods
Deep pain during sex
Painful urination
Pain during bowel movements
Menstrual rectal bleeding or blood in the urine
Shoulder-tip pain
Infertility

The test can be performed while using hormonal treatment and at any point during the menstrual cycle.

When is Ziwig Endotest® not suitable?

Current contraindications include:

Pregnancy
A history of cancer
HIV
An active infection at the time of collection
Poor saliva collection conditions can also interfere with sample quality.

Food, toothpaste, lipstick, tobacco, chewing gum, blood and nasal secretions can all potentially contaminate the saliva sample.

Full collection instructions should therefore be followed carefully.

What happens after a positive result?

A positive result indicates that the molecular signature associated with endometriosis has been detected.

It does not provide anatomical mapping of the disease.

Further clinical review and imaging may therefore still be appropriate to understand the potential location and extent of endometriosis and to discuss treatment options.

And what happens after a negative result?

A negative result indicates that the molecular signature has not been detected.

However, symptoms should still be taken seriously.

No investigation exists in isolation.

Your symptoms, medical history, examination, imaging and other relevant investigations all contribute to the wider clinical picture.

Where symptoms remain significant or persistent, further medical assessment may still be appropriate.

Where does Endotest® sit within UK endometriosis care?

This is an evolving area.

Current NICE NG73 guidance continues to recommend clinical assessment and imaging within the investigation of suspected endometriosis.

Separately, NICE is currently carrying out an early-use assessment of technologies for the rapid diagnosis of endometriosis, which specifically includes Endotest.

The final NICE guidance is currently expected on 8 October 2026.

Until then, it is more accurate to think of Endotest® as an additional private diagnostic option rather than a replacement for established endometriosis pathways.