Endometriosis pain: why it stays when the lesions are gone

I am writing this text for the situation after the consultation. You are holding a report and you do not understand why the numbers in it have so little to do with your daily life. Or you have an operation behind you that went well, and the pain is there anyway. Both are known patterns, and the explanation decides where the next step is taken.

The contradiction many women with endometriosis know

Many women with endometriosis know this pattern from the waiting room. In some, the laparoscopy shows lesions in several places and a high stage, and daily life is still manageable. In others, a few small spots on the peritoneum are found, and several working days are lost in some months.

If you know this pattern, you have probably wondered whether something is wrong with you. The link between the amount of visible tissue and the strength of the pain is surprisingly weak in the data. That is not a comforting phrase, that is what the studies say.

What the data say about the link between findings and pain

A Polish series of 138 women operated on for advanced disease reached the same conclusion in 2026: no significant association between the overall intensity of pelvic pain and the rASRM stage. Where a lesion sits explains the type of pain rather well. The stage does not explain its strength. PMID: 41977023 · DOI: 10.3390/jcm15072725 [Cohort, surgical series, n=138]

Both papers have their limits. These are women who had surgery, so a selected group. Together they show one thing: the map of the findings and the map of the pain are not the same map.

The surgical assessment is a great achievement and it remains the foundation. It simply answers a different question than the one about how strong the pain is.

And now you know why that sentence from the beginning is heard so often and still does not hold.

The four sources that feed the pain

Pain in endometriosis is not a single phenomenon. It is fed by at least four sources that run at the same time and can amplify each other. That is why a single measure is often not enough.

Source one: the inflammatory stimulus at the lesion

Displaced tissue in the abdomen is a construction site for your immune system. It sends clean-up cells there, and those cells release messengers. Their actual job is repair, and along the way they can make nerve endings more sensitive.

Important for context: this is a tissue study. It describes a mechanism, it does not prove a treatment. I draw that line very strictly here, because online it often gets blurred.

Source two: the nerve fibres in the tissue itself

This is the part I consider the most underestimated. An endometriosis lesion does not simply sit in the tissue, it attracts nerve fibres. In tissue sections from the lining and the muscle layer, stained nerve fibres were clearly increased in endometriosis. So it is not only the lesion that is wired, but the lining itself.

A small Chinese series of 32 peritoneal lesions compared women with and without pain. With pain, fibre density was 3.8 plus minus 1.7 per square millimetre, without pain 1.7 plus minus 0.5. It correlated with pain intensity, reported as r equal to 0.855, and was not associated with location or stage. That is the most precise available support for the core sentence of this article, and at the same time a very small study.

In Sydney it was also shown that nerve growth factors are produced within the lesion itself. A paper from Innsbruck and Berlin found bowel lesions to be far more densely populated with fibres than peritoneal lesions.

Source three: when two organs make each other louder

Uterus, bladder and parts of the bowel report into the same section of the spinal cord. Imagine a telephone exchange in which several extensions share one line. When two ring at once, it gets loud.

Source four: when the alarm system stays turned up

And now the part that gets misunderstood most often. Pain is not a measurement, pain is an alarm. Between the stimulus in the tissue and what you feel sits an amplifier with movable controls. Under long-lasting input they can stay in a louder position.

And now you know why a single explanation for this pain falls short.

Why a long pain history changes the nervous system

Maybe you know this moment: you tell your story for the fifth time, since when it hurts and what you have already tried. And at some point you notice that the year in your story keeps sliding further back. Twelve years. Fourteen. Since school. That number is not a side note. It is a medical finding in itself.

The image carries two things at once. The sensitivity is real and measurable. And the alarm still means something. An oversensitive detector does not turn the smoke into imagination.

What the imaging shows

The same working group measured the anterior insula four years later. In endometriosis-associated pelvic pain, glutamine and glutamate levels there were raised and the connection to the medial prefrontal cortex was stronger, and in endometriosis without pain they were not. So the amplifier is measurably running louder. That is no proof that the pain comes from your head, it is proof that it is co-processed there. PMID: 26456676 · DOI: 10.1016/j.jpain.2015.09.008 [Cohort, imaging and spectroscopy]

I say this so plainly because many women have already heard the term, usually in the short version: so it is all in your head. That short version is wrong and it does damage. It makes women stop naming their pain.

What I still take from the Swedish paper: duration counts. Someone who gets a treatment that is taken seriously early on has a better starting point than someone who hears for ten years that this is normal. If many years have already passed in your case, that is not a failing on your part. It describes how long your pain was not taken seriously enough, and it rules out none of what is still possible now. The 2025 Canadian guideline on primary dysmenorrhea says exactly that: period pain is frequently undertreated, and untreated persistent period pain can develop into a chronic pain syndrome.

And now you know why the question about the duration of your pain sits right at the front of a good history.

What that means for surgery, honestly said

The appointment came, the operation went well technically. And three months later you are sitting there with the same pain. That is the most common disappointment I hear on this topic, and it almost always arrives together with a feeling of having failed.

One sentence up front that applies to this whole section. Nothing here is an argument against an operation that has been recommended to you. Surgery can be necessary in endometriosis, it clarifies the diagnosis and can protect organ function. That decision is made by your gynaecological team together with you. What follows is only about the question of what an operation does to your pain system and what it does not.

And now you know why an honest clarification of expectations is part of a good preparation for surgery.

The accompanying problems that keep the pain going

Many women know this experience. You go in because of the lower abdomen and mention in passing that you have to get up three times at night, that your belly is bloated all the time and that your back hurts too. And then the conversation stays with the lower abdomen. Those passing remarks are not side notes. They are often the part where something can actually be moved.

The pelvic floor

The pelvic floor is muscle. Muscles that tense against pain for years stay tense. Points develop in them that can trigger a radiating pain under pressure.

In a Canadian paper on 163 women with endometriosis, 37 percent had both severe deep dyspareunia and tenderness at the bladder or pelvic floor. This group had the highest scores in the sensitization questionnaire, 51.3 versus 30.9. That is an association, not a causal chain, but a good reason to look for it.

The bladder

Bladder pain syndrome sits anatomically right next to the uterus and in the same spinal segment. An Italian review compiled frequencies from ten years of literature: a hypertonic pelvic floor disorder in an estimated 50 to 87 percent, and in women with chronic pelvic pain a bladder pain syndrome in 61 percent, endometriosis in 70 percent and both together in 48 percent.

These numbers come from specialist clinics, not from the general population. That is why I name them explicitly with this context. They justify a question in the consultation, not a percentage that applies to you personally.

In an American registry of 431 people with bladder pain syndrome, 19 percent also had a diagnosis of endometriosis. This group less often had the typical bladder wall changes and instead more often had irritable bowel syndrome, fibromyalgia and vulvodynia. So when both occur together, the problem often sits less in the bladder wall than in the system that supplies the bladder.

The bowel

Endometriosis and irritable bowel syndrome are regularly confused with one another and regularly occur together. You know the mechanics from the section on spinal segments. There is more on this in Endometriosis and the bowel and in Irritable bowel syndrome: finding the causes.

Fibromyalgia and the family of overlapping pain conditions

Sometimes a woman with endometriosis says a sentence that changes everything: actually, something hurts everywhere. That is the point where I ask about the order of events. What came first, what was added, in which year.

A narrative review describes six conditions that frequently occur together in chronic pelvic pain: endometriosis, bladder pain syndrome, vulvodynia, myofascial pain, irritable bowel syndrome and primary dysmenorrhea. That is a map, not a proof. If you have whole-body pain, Fibromyalgia and mould describes one of the perspectives that we add in our practice.

And now you know why the apparent side remarks in a conversation are sometimes the decisive trail.

Pain in unfamiliar places: legs, ovulation, after the period

Three questions come up particularly often, and they share the same root. I answer them together, because they explain each other.

Why endometriosis can pull into the legs

There are two routes for this, a common one and a rare one.

The common route is referred pain. An organ has no address of its own in consciousness. It reports through a spinal segment, and that segment also supplies areas of skin and muscle. In a heart attack it is the left arm, for the uterus it is the sacrum, the buttocks and the thighs. In the Italian paper this referred muscle tenderness was measured directly. It is not a feeling, it has a pressure threshold.

The rare route is direct involvement of nerves. Endometriosis outside the lesser pelvis is rare. For a location behind the peritoneum including the region of the sciatic nerve, magnetic resonance imaging is the method of choice, not laparoscopy. A case report from Ghent documents involvement of the pudendal nerve and the sciatic nerve with muscle wasting as a consequence.

Why it can hurt around ovulation

Around ovulation several things change at the same time. Blood flow in the lesser pelvis increases, tissue tension changes, and the peritoneal fluid has a different composition than the week before. At normal sensitivity this stays below the perception threshold. With a lowered threshold it is enough.

In the ENDO study the overall pain picture in women with endometriosis was broader than in women without this finding. I do not derive a statement about ovulation in particular from this, because the study did not analyse it that way.

A new, very severe one-sided pain in mid-cycle still belongs in a prompt assessment. Not because it is usually dangerous, but because the few cases in which it is leave no time.

Why the pain does not stop after the period

As long as the pain comes mainly from the stimulus at the tissue, it follows the menstrual cycle. As soon as the alarm system has become more sensitive, that rhythm no longer applies.

The 2025 Berlin paper examined cyclical and non-cyclical pain separately. Hypersensitivity to cold and to blunt pressure was more pronounced in non-cyclical pain. That fits what women describe themselves: first it was the period. Then it was the days before. Then at some point it was almost always.

And now you know why a pain diary sometimes says more about the direction of treatment than another scan.

Treatment paths with an honest look at the evidence

Now the part you probably came for. I do not sort the paths by popularity, but by what the studies support. A text that makes everything look equally good is of no use to you at your next decision.

One sentence up front: there are no dosages and no protocols here. And no sentence that invites you to change an ongoing treatment on your own. Every adjustment belongs under medical guidance.

Non-steroidal anti-inflammatory drugs: surprisingly thinly researched

Online this is often shortened into a headline: painkillers do nothing in endometriosis. That is not what it says. What is missing are good trials. That is a statement about the research, not about your medication.

Hormonal options: first line in the guidelines, and still not the whole pain

The German S2k guideline of 2025 recommends primary hormonal treatment as the first-choice approach, complemented by surgical and multimodal approaches. That is the frame your gynaecological team works within, and it is well founded.

So why does a hormonal treatment still not always take the pain away? Because it acts on two of the four sources and not on the other two. It influences the stimulus at the tissue and the cyclical dynamics. It does not turn back any control in the spinal cord, does not relax a pelvic floor and does not calm an irritated bladder.

Gabapentin: a large trial that came out negative

A word on opioids

Opioids are an important tool in acute pain and in cancer medicine. In chronic pain without a cancer cause, pain medicine has become clearly more reserved, among other reasons because tolerance, side effects and a possible increase in pain sensitivity can play a role with longer use. I deliberately do not name a number here, because I have not checked a source specifically on chronic pelvic pain. If an opioid is part of your treatment, that belongs in specialist pain care, and never in a change you make on your own.

Pelvic floor physiotherapy: clinically established, study base thin

Here I have to be honest, even though it goes against what you might expect from an integrative practice. I searched specifically for randomised trials on pelvic floor physiotherapy in endometriosis and found none that I could cite with a clear conscience.

A muscle that tenses against pain for years changes. Relaxing it is mechanistically plausible and low-risk in experienced hands. That is clinical tradition with good reasoning, but not a proven treatment in the sense of a randomised trial.

Multimodal pain therapy: the best studied concept

Important for honesty: these data come from back pain research. The transfer is a transfer, and I name it as such. What carries the bridge: the German S2k guideline of 2025 names multimodal approaches in endometriosis itself, and its authorship includes pain medicine and psychosomatic medicine alongside gynaecology.

37 professional societies, organisations and patient support groups contributed to the 2025 version. If you want to address more than one level in your treatment, you are moving inside this guideline and not beside it. PMID: 41684533 · DOI: 10.1055/a-2760-4867 [Guideline, consensus guideline, S2k]

Psychological approaches: work on the alarm system, not on an imagination

I know that many women close the text at this point. Too often the offer of psychological support was the polite version of there is nothing to be found. This here is something else. If your alarm system is turned up, working on that system is part of the treatment. The pain itself is never in question. It is taken as given.

A special case is understanding itself. A meta-analysis with nine studies and 1,038 people with chronic low back pain found short-term effects of pain education on pain intensity and catastrophising as well as lasting effects on fear of movement. The confidence intervals are wide, and again: back pain, not endometriosis.

Movement, heat, TENS and acupuncture

Movement was examined in a Cochrane overview of 21 reviews with 381 studies and 37,143 participants. Physical function improved significantly in 14 reviews, and for pain intensity the results were inconsistent. Specifically in endometriosis, a 2025 meta-analysis could pool only two of six studies, with better scores for quality of life and sense of control. No miracle solution for the pain score, but very low-risk.

Heat appears in almost every guide. I found no verifiable trial on local heat specifically in endometriosis. It therefore remains low-risk self-help that many women describe as pleasant, without my being able to offer you a number for it.

Acupuncture has the comparatively best data base among the complementary approaches, and even that is thin. A review with 15 studies and 1,018 patients reported a reduction in period pain of 2.40 points on average on the visual analogue scale compared with sham acupuncture, but calls the overall effectiveness insufficiently supported in its conclusion. A second meta-analysis with 331 participants found an advantage for pelvic pain at low certainty of evidence.

Several reviews, all with effects, all with small studies, and the authors themselves stay reserved. I do not derive a recommendation for every woman from this, only that a trial is defensible at good tolerability once the basics are in place.

On vagus stimulation at the ear there is a pilot study with 15 patients with endometriosis-associated pelvic pain. A trend towards lower evoked pain intensity was found, as well as a significant decrease in anxiety. The word proven does not belong here, n equal to 15 is too small for that. The approach is described in more detail in The gut-brain axis and vagus stimulation.

And now you know why a good treatment in this field rarely consists of a single measure.

The central sentence and what follows from it

What a good consultation on this topic should deliver

This is explicitly not a criticism of gynaecology. In a field that covers everything from routine care to cancer screening, time is short and the training focus lies elsewhere. The gynaecological assessment remains the foundation. What a pain medicine perspective can contribute comes on top of it and not in its place.

Where the environmental perspective fits, and where it does not

In our practice we also ask about environmental factors in hormonal complaints, about mould in the home, about heavy metals, about substances that can dock onto hormone receptors. For some of these substances there are good mechanistic data, and the basics are described in Xenoestrogens in everyday life and in Endometriosis: an integrative look at the causes.

For this article, though, a clear boundary applies. None of the three current guidelines recommends a search for environmental factors in endometriosis pain, and that reticence is understandable. What is missing are intervention studies in humans showing that targeted environmental testing or an elimination approach measurably lowers the pain. And it explicitly does not follow that every hormonal disorder has an environmental cause. For me the environmental perspective belongs to the search for causes, not to pain therapy.

Three levers you can start with

• Keep a simple pain diary for two menstrual cycles. One score per day, plus a keyword on bladder, bowel and sleep. That shows you whether your pain still hangs on the cycle or has already uncoupled from it.
• Bring up bladder, bowel and back yourself at your next appointment. Not at the end, but early. Otherwise these complaints slip to the back of the conversation.
• Actively ask for an examination of the pelvic floor. It is part of the international research standard and costs nothing but time.

What is deliberately not on this list: anything about your medication. Neither a pill nor hormone replacement therapy, a GnRH analogue or a painkiller gets changed because of a blog article. Those conversations belong in the consultation.

And now you know why so many questions are asked about endometriosis pain that at first glance have nothing to do with the uterus.

Frequently asked questions about endometriosis pain

Where this topic connects to the rest of your body

Endometriosis pain rarely stands alone. Depending on which part is loudest in you right now, the next step leads in a different direction.