Endometriosis: What It Is, Why Diagnosis Is Often Delayed - and How to Advocate for Yourself

It’s Endometriosis Awareness Month, but awareness only matters if we understand what we’re looking for.

Endometriosis affects around 1 in 10 women. Yet in the UK, the average time to diagnosis is still around 8–9 years.

That means many women spend years living with symptoms before receiving answers.

I know this first-hand. I wasn’t diagnosed with endometriosis until I was 40.

Looking back, there were signs much earlier - but like many women, I assumed severe symptoms were simply something I had to tolerate.

They weren’t.

What is endometriosis?

Endometriosis is a chronic inflammatory condition where tissue similar to the lining of the uterus grows outside the uterus.

This tissue still responds to hormones such as oestrogen throughout the menstrual cycle. But because it is located outside the uterus, it can trigger inflammation, irritation of surrounding tissues, and over time the formation of scar tissue and adhesions - sometimes described as sticky bands that can cause organs to attach to each other.

These adhesions may affect structures such as the ovaries, bowel, bladder, or pelvic lining, which helps explain why symptoms can vary so widely between individuals.

While hormones play a role in driving the activity of the tissue, research increasingly shows that immune and inflammatory processes are also central to the development and persistence of endometriosis.

This is one reason the condition can be complex to diagnose and manage.

How endometriosis can show up

One of the reasons endometriosis is so often missed is that it does not look the same in every woman. For some, it begins as severe period pain that is easy to dismiss as “just part of being a woman”. For others, the first signs are heavy bleeding, bloating, pain during sex, bowel symptoms around their period, or a growing sense that their cycle is taking over too much of their month. That variation matters, because endometriosis is not defined by one single symptom pattern.

Common symptoms include painful periods, chronic pelvic pain, heavy menstrual bleeding, pain during sex, painful bowel movements or urination, bloating, nausea, fatigue, and fertility difficulties.

Symptoms are often cyclical at first, meaning they tend to flare around ovulation or in the days before and during a period. Over time, though, pain can become more persistent and less clearly linked to the cycle. That shift can happen as inflammation becomes more established, pelvic tissues become more sensitised, and the nervous system starts to stay on higher alert. This is one reason some women eventually describe a constant background ache, pressure, or fatigue even when they are not bleeding.

Another important point is that symptoms do not always reflect severity in a simple way. Some women with relatively limited visible disease have debilitating pain, while others with more extensive lesions may have fewer symptoms. Pain can be influenced not only by where lesions are found, but also by inflammation, immune activity, adhesions, pelvic floor tension, and changes in pain processing over time. So if your symptoms feel significant, they deserve to be taken seriously regardless of what a scan shows or whether someone else appears to be “worse” on paper.

In practice, what I want women to notice is not just whether periods are painful, but whether their cycle is interfering with normal life. Are you cancelling plans each month? Missing work? Losing sleep? Needing stronger and stronger pain relief? Feeling wiped out by bleeding, bloating, pelvic pain or bowel symptoms? Those patterns matter. Endometriosis is becoming more common, underdiagnosed, and still too often normalised. If symptoms are recurring month after month, especially if they are escalating or affecting fertility, they are worth investigating properly.

Why diagnosis is often delayed

Despite affecting millions of women worldwide, endometriosis is still frequently misdiagnosed or overlooked.

Symptoms may be attributed to:

• “Just painful periods”

• Irritable bowel syndrome

• Hormonal fluctuations

• Stress or anxiety

  
  

Another challenge is that endometriosis does not always appear on ultrasound, and normal blood tests do not rule it out.

Because of this, diagnosis often requires

referral to a specialist.

This is one of the reasons the average diagnosis delay in the UK remains 8–9 years.

Earlier recognition and investigation can help women access appropriate care sooner.

When symptoms shouldn’t be ignored

A useful way to think about symptoms is to consider their impact on your life, rather than just their presence.

For example:

• Are you regularly cancelling plans because of pain or fatigue?

• Do your periods disrupt work, sleep, or daily activities?

• Are you relying heavily on pain relief to get through each cycle?

• Are symptoms getting worse over time rather than improving?

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These patterns can indicate that something more than typical menstrual discomfort may be happening.

If symptoms are recurring month after month, it is reasonable to seek further investigation.

Preparing for a GP appointment

If you suspect endometriosis, preparing for your GP appointment can help you communicate your symptoms clearly.

To make this easier, I’ve created a simple Endometriosis GP Checklist that you can take with you to your appointment.

The checklist helps you:

• Identify key symptoms

• Explain how symptoms are affecting your life

• Ask clear questions about referral and next steps

• Understand what tests can and cannot rule out

  
  

You can download the checklist here:

Download the Endometriosis GP Appointment Checklist here.

A final note

Medical diagnosis and appropriate clinical care are essential when managing endometriosis.

But support does not stop at diagnosis.

Alongside medical treatment, there are evidence-informed ways

to support inflammation, hormonal regulation, and overall resilience. These approaches work best when combined with appropriate medical guidance.

If you recognise these symptoms in yourself, please don’t ignore them.

Endometriosis is common, underdiagnosed, and often misunderstood - but earlier recognition can make a real difference.