A Normal Scan Doesn’t Rule Out Endometriosis
What updated guidance could mean for earlier recognition and support
It is estimated that around 1 in 10 women in the UK are affected by endometriosis. For many women, getting an endometriosis diagnosis has historically been a long and frustrating process. Endometriosis UK’s latest 2026 report, based on the lived-experience of over 3,000 women with endometriosis, found that diagnosis takes an average of 9 years and 4 months in the UK from first presenting to a GP with symptoms, longer in Scotland, and longest overall for women from ethnically diverse communities.
It’s also worth noting in the same report, that women often experience symptoms for several years before seeking medical help. This raises important questions about how we perceive cyclical or persistent pain and other menstrual symptoms, and how easily these can become normalised until the pain or disruption to everyday life becomes difficult to tolerate.
Endometriosis UK also reports women’s lived experiences of having symptoms dismissed or not taken seriously when they do seek help. Experiences like these may further discourage women from returning for support or reinforce the belief that their symptoms are simply something they are expected to live with.
Symptoms therefore can be downplayed. Perhaps most confusingly, someone may have an ultrasound reported as normal and and then assume that endometriosis has been ruled out. Recent changes to clinical guidance changes this assumption.
In November 2024, the National Institute for Health and Care Excellence (NICE) updated its guidance on diagnosing endometriosis, including the emphasis on more timely investigation and referral. Additionally, Scotland’s new Women’s Health Plan: Phase Two 2026–2029 has subsequently committed to reviewing the existing Scottish Endometriosis Care Pathway against that updated guidance.
So, what has actually changed?
Endometriosis can present in different ways
Endometriosis occurs when tissue similar to the lining of the uterus is found elsewhere in the body. It can cause inflammation, pain and scarring, although the severity and pattern of symptoms vary considerably between individuals. NICE advise that endometriosis should be suspected in women (including young women aged 17 and under) presenting with 1 or more of the following symptoms or signs:
chronic pelvic pain (more than 6 months)
period-related pain (dysmenorrhoea) affecting daily activities and quality of life
deep pain during or after sexual intercourse
period-related or cyclical gastrointestinal symptoms, in particular, painful bowel movements
period-related or cyclical urinary symptoms, in particular, blood in the urine or pain passing urine
infertility in association with 1 or more of the above
Individual experience matters
The NICE guidance also highlights that pain is not experienced or communicated identically by everyone. Cultural background and beliefs, socioeconomic circumstances and neurodivergence can all influence how symptoms are expressed and how people experience and access healthcare.
There is also growing research into adverse childhood events or experiences (ACEs). A large 2025 Swedish cohort found a graded association between childhood adversity and later diagnosis of endometriosis, with higher risk as the number of adversities increased. This is an important area of research, but it does not mean that trauma causes endometriosis, rather the findings reinforce the importance of seeing the whole person, recognising that biological, psychological and social experiences may intersect with pain, health and healthcare access.
Ultrasound now plays an earlier role
A particularly important change in the 2024 NICE update relates to ultrasound.
NICE now recommends offering a transvaginal ultrasound to all with suspected endometriosis, even if abdominal or pelvic examination is normal. The scan can help identify ovarian endometriomas, deep endometriosis involving areas such as the bowel, bladder or ureter, and other possible causes of symptoms. It can also help determine the most appropriate referral route. If a transvaginal scan is unsuitable or declined, NICE advises considering a transabdominal pelvic ultrasound instead.
This is a change from the older pathway in which ultrasound was more likely to be considered later, for example after treatment had been unsuccessful.
Investigation, referral where indicated, and initial pharmacological treatment can take place in parallel.
Previously, the experience for some women could feel much more sequential:
Try treatment
Wait
Return
Try something else
Wait again
Eventually initiate investigation and referral to secondary care like gynaecology
Wait again
Get a diagnosis
The updated guidance recognises that these processes do not necessarily need to happen sequentially, one at a time. Investigation, referral and initial treatment can take place in parallel, theoretically supporting a more timely pathway however, NICE anticipates that the updated approach may lead to more investigations and secondary-care referrals. For me this suggests potentially a longer wait for assessment, increasing the importance of women seeking support early.
A normal ultrasound does not mean that endometriosis has been ruled out.
NICE specifically advises healthcare professionals not to exclude endometriosis simply because the examination and ultrasound are normal. Referral may still be needed if symptoms persist or significantly affect everyday life. Laparoscopy may also still be considered where endometriosis is suspected even if ultrasound or MRI has not shown disease. That does not mean everyone with pelvic pain needs surgery. It does mean that imaging is one part of the diagnostic picture rather than a simple yes/no test.
In Scotland, the Women’s Health Plan: Phase Two 2026–2029, published in January 2026, includes endometriosis as part of a broader commitment to improve gynaecological and reproductive healthcare. The Centre for Sustainable Delivery has been asked to review Scotland’s existing Endometriosis Care Pathway against the updated NICE guidance, identify gaps and opportunities for improvement, and to support the development of clinical pathways with patient-friendly versions.
What I find encouraging in the new plan is the recognition that support should not depend entirely on reaching a definitive diagnosis.
Believe the symptoms, support the person and investigate appropriately, rather than making support conditional on having a diagnostic label first.
The plan describes the possibility of a working diagnosis in primary care, followed where necessary by confirmation in secondary care. It also acknowledges that not everyone will want an invasive procedure if their symptoms can be appropriately managed without one.
I was asked about aspirin and endometriosis?
You may have seen aspirin, particularly low-dose or “baby aspirin”, discussed online in relation to endometriosis and fertility. There is some theoretical plausibility behind the interest: aspirin affects inflammatory and prostaglandin pathways and these pathways are also implicated in endometriosis, so the connection makes sense.
A 2024 systematic review found that research specifically examining aspirin and endometriosis was sparse however, concluding that currently there is insufficient evidence to recommend aspirin as a treatment for endometriosis. A more recent laboratory research study produced interesting findings around endometrial cell function, but these studies cannot tell us whether taking aspirin improves endometriosis symptoms or fertility in real women's bodies.
Low-dose aspirin acts primarily as an antiplatelet medicine, reducing the ability of platelets to clump together and has an established evidence-base for its use for some people e.g. with established cardiovascular disease, and for some pregnancies where there is an increased risk of pre-eclampsia. Aspirin may also increase bleeding risk in some people. Some women with endometriosis experience heavy menstrual bleeding, which can increase their risk of iron deficiency and anaemia, aspirin could increase blood loss for some women.
Over the counter medicines like aspirin, can sometimes lead to the assumption that they are harmless or appropriate for everyone, however as aspirin can increase bleeding risk and interact with other medicines, I’d always recommend speaking to a healthcare professional like your GP if you are considering if it would be helpful for you.
What about histamine and mast cells?
Endometriosis involves a complex inflammatory environment, and researchers are increasingly interested in the role of mast cells. These immune cells are found in increased numbers and appear more activated within some endometriotic lesions. When activated, mast cells can release histamine, inflammatory cytokines, prostaglandins and other compounds that may contribute to inflammation and sensitise nearby pain nerves.
There may also be interaction between prostaglandin, oestrogen and mast-cell signalling, however, this is an emerging area of research. It does not currently mean that endometriosis is a “histamine condition”, nor is there sufficient evidence to recommend routine antihistamines or a low-histamine diet as endometriosis treatments, however where symptoms co-exist, an assessment of what might be contributing to this symptom is always warranted.
What about nutrition and lifestyle?
There is growing interest online in “endometriosis diets”, supplements and anti-inflammatory protocols. Endometriosis is an inflammatory, hormone-responsive condition, but its causes remain incompletely understood and are likely to be multifactorial, with genetic, hormonal, immune and environmental factors potentially contributing. This means there is currently no particular food, diet or supplement that has been proven to treat or reverse endometriosis.
Nutrition and lifestyle medicine still has a role in supporting health, nutritional adequacy and some associated symptoms, but that is different from treating the disease itself. Nutritional therapy therefore sits alongside appropriate medical assessment and treatment and does not replace it.
Someone living with endometriosis may also be dealing with altered appetite, bowel symptoms, fatigue, disrupted sleep, mood issues, pain, restricted eating where particular foods appear to worsen symptoms, or difficulties maintaining a nutritionally adequate diet. Heavy, frequent or prolonged menstrual bleeding can also contribute to iron deficiency. Scotland’s new Women’s Health Plan includes an action asking healthcare professionals to consider full blood count and ferritin testing (iron stores) where women or girls present with heavy, frequent or prolonged menstrual bleeding.
Nutritional Therapy is personalised and I believe individual assessment matters far more than imposing a generic “endometriosis diet”.
As a Functional NT I would consider:
· Your current diet and assess for niutritional repletenes and antoxidant intake
· The whole-body microbiome (the gut, oral and vaginal)
· Detoxification pathways
· The diurnal circadian rhythm alongside sleep and stress
· Current exposure to endocrine disrupting chemicals (EDCs)
· Any symptoms such as histamine intolerance
· Functional testing support
When should you ask for help?
Pain that repeatedly interferes with work, school, relationships, sleep, exercise or everyday life deserves attention. The same applies to significant cyclical bowel or bladder symptoms, persistent pelvic pain or painful sex.
Periods can be uncomfortable. They should not routinely stop you living your life.
Don’t delay asking your GP or healthcare provider for assessment. Even if you have previously been told that a normal ultrasound means you cannot have endometriosis, the updated guidance is very clear that a normal scan does not exclude endometriosis.
NICE recommends keeping a pain and symptom diary if endometriosis is suspected, as this can help identify patterns and support discussions with your healthcare professional. It can also be useful to note where symptoms occur in relation to your menstrual cycle.
I’d also encourage reading the NICE guidance and going to your appointment with a clear record of the symptoms that concern you. If you are experiencing heavy, frequent or prolonged menstrual bleeding, Scotland’s Women’s Health Plan recommends that healthcare professionals consider a full blood count and ferritin measurement to identify or exclude iron deficiency, and even if not in Scotland, advise your healthcare provider of heavy, prolonged bleeding and ask if an assessment of your blood count and iron status can be done if you're concerned.
Being informed about the guidance can be really helpful. It’s absolutely reasonable to say: “I’m wondering whether this could be endometriosis because I’m experiencing…” and describe the symptoms and how they are affecting your life. It’s OK to advocate for your own body and to ask questions.
In my experience of working in the NHS for more than 38 years, collaborative conversations are often very helpful. NICE emphasises shared decision-making and that healthcare professionals listening to your views and concerns, and discuss options with you.
At Lynda Mutter Health, nutritional therapy can complement your medical care by exploring nutrition, digestive health, energy, eating patterns, mood, lifestyle, individual health history, and sometimes functional testing. It does not replace assessment or treatment from your GP or gynaecology team, but it can form a personalised approach to support your health and wellbeing helping you thrive with endometriosis.
References
NICE. (2024). Endometriosis: diagnosis and management (NG73). Updated 11 November 2024. Recommendations | Endometriosis: diagnosis and management | Guidance | NICE
Scottish Government. (2026). Women’s Health Plan: Phase Two 2026–2029. https://www.gov.scot/publications/womens-health-plan-phase-two-2026-2029
Scottish Government. Endometriosis: illnesses and long-term conditions. https://www.gov.scot/policies/illnesses-and-long-term-conditions/endometriosis
NHS Scotland Right Decisions. Integrated Endometriosis Referral Care Pathway. https://www.rightdecisions.scot.nhs.uk/ggc-primary-care/womens-health/womens-health-referral-guidance/endometriosis/endometriosis
Mikhaleva, L, M., et al. (2021).Current Knowledge on Endometriosis Etiology: A Systematic Review of Literature ResearchGate
Monnin, N., Fattet, A, J., Koscinski, I. (2023). Endometriosis: Update of Pathophysiology, (Epi) Genetic and Environmental Involvement. https://pmc.ncbi.nlm.nih.gov/articles/PMC10046867
McCallion, A., et al. (2022). Estrogen mediates inflammatory role of mast cells in endometriosis pathophysiology. https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.961599
Duraj, J., et al. (2026). Immune-nutritional interactions in endometriosis: current evidence and future perspectives in disease management. https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2026.1940772
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