Endometriosis · the figures

89 months. That's the median, not the exception.

Endometriosis is often dismissed as rare or vague. The figures tell a different story: it is one of the most common gynecological disorders, with a diagnosis process that structurally takes years.

How common it is

Bigger than you think

89 months

median time between the onset of the symptoms and the diagnosis in Dutch research: more than 7 years.

400,000 to It is estimated that 500,000

women in the Netherlands have endometriosis: the Endometriosis Foundation itself consistently mentions 1 in 10 women.

~10.000

women visited the GP for endometriosis in 2022, possibly an underestimate due to how the diagnosis is registered.

That last figure shows the problem at a glance: if 10,000 women visit the GP per year compared to an estimated 400,000 to 500,000 with the condition, then the vast majority are not, not yet, or never visible. The NVOG now explicitly recognises the problem: at the beginning of 2025, the professional association launched its own platform with the explicit mission to shorten the diagnosis process from 7 to 1 year.

What is striking

The delay is in three phases

The Dutch study reports separate medians of 7 months for patient delay, 35 months for GP delay and 5 months for gynaecologist delay. The median for the complete route was calculated separately and is 89 months. The phase medians come from different distributions and therefore cannot be added to obtain the median total. The 42-month difference is not a separate unexplained phase. Women who wanted to have children received a diagnosis faster than women who presented with pain. Gynaecologists confirmed in early 2024 that a diagnostic route of around 7 years still occurs, although several hospitals were seeing more referrals.

“From a few months to up to 30 years. That's how much time there can be between the first complaint and the diagnosis.”

Why it was missed is

It is not in the patient, but in the look

Menstrual pain is considered normal

Severe pain is often seen as something that is simply part of having a period, rather than a signal.

GPs underestimate the occurrence

Research confirms that GPs underestimate both the prevalence and the degree of delay.

Not a simple test

Only keyhole surgery makes the diagnosis with certainty. A normal gynecological examination or an ultrasound is often not enough.

What the numbers do not tell

What does and does not count

Yes counted

What is visible

Women who are ultimately diagnosed
Treatment results in specialized endometriosis centers
Direct healthcare costs of laparoscopy and hormone therapy

Not counted

What is invisible remains

Anyone who is still in the middle of the years-long process sits
Who has now come to see the pain as chronic and normal
Missed school days, working days and fertility opportunities due to the delay

Sources

Where these figures come from

Median of 89 months and separate phase medians

Staal, Van der Zanden and Nap retrospectively studied 139 patients with endometriosis. They reported a median total duration of 89 months and separate medians of 7, 35 and 5 months for patient, GP and gynaecologist delay. These phase medians cannot statistically be added to obtain the median total. See PubMed.

Diagnostic route still around 7 years, confirmed in 2024/2025

NOS, gynecologists from UMC Groningen and Catharina Hospital about persistent diagnosis delays. See nos.nl. The NVOG launched Endometriosis Wiser in 2025 with the aim of shortening the process from 7 to 1 year. See nvog.nl.

1 in 10 women, 400,000 to 500,000 in the Netherlands

Endometriosis Foundation, the Dutch patient organization, information page compiled with the NVOG endometriosis working group. See endometriose.nl.

~10,000 GP visits in 2022, possible underestimate

NIVEL report on women-specific conditions, commissioned by ZonMw and the Ministry of Health, Welfare and Sport, with the explicit note that endometriosis falls under an ICPC subcode. See nivel.nl.

Delay divided among patient, GP and gynecologist

Zorgkrant.nl, summary of Van der Zanden's thesis. See zorgkrant.nl.

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