What Is Endometriosis? A Complete Evidence-Based Guide

If you've been told your endometriosis is "just periods gone wrong" or "just tissue outside the uterus," I need to stop you right there. That definition has hurt more people than it's helped—including me.

When I was 24, a surgeon told me my endometriosis was "not that bad" during a diagnostic laparoscopy. I was told to take birth control and essentially get over it. By 27, I was having a second surgery. By 28, I was being pushed toward a hysterectomy. I was barely married. I wasn't broken. But medicine was treating me like I was.

It wasn't until I got deeper into the research—and understood what was actually happening inside my body—that everything changed. Not just my symptoms, but my sense of being seen and believed in my own care.

Let me tell you what endometriosis actually is.

Beyond the "Tissue in the Wrong Place" Definition

Yes, endometriosis involves endometrial-like tissue growing outside the uterus. But that's like defining a car as "metal in a shape." Technically true, completely useless.

What's actually happening is far more complex. Endometriosis is a chronic, progressive, multi-system inflammatory condition. The tissue growing outside your uterus isn't just passively sitting there—it's actively secreting inflammatory molecules, creating adhesions, recruiting immune cells, and rewiring your nervous system. It's less like a weed in the wrong garden, and more like a systemic alarm system that's stuck in the "on" position.

And here's the part that matters: the inflammation isn't localized to your pelvis. It ripples through six interconnected systems that control how you move, digest, feel pain, and live.

The Six Systems Endometriosis Affects

Think of endometriosis less like a gynecological disease and more like a disease that happens to involve the reproductive system.

1. The Immune System

In endometriosis, your immune system is fundamentally dysregulated. You have too many macrophages in your peritoneal fluid (the fluid around your organs). These cells are supposed to clean up debris—but instead, they're releasing pro-inflammatory cytokines like IL-6, IL-8, and TNF-alpha. In simple terms: your body's security guards are overstimulated and seeing threats everywhere. This hyperactivation is why you might have autoimmune features alongside your endo.

2. The Nervous System (Central Sensitization)

About 41.4% of people with endometriosis develop central sensitization—a state where your nervous system amplifies pain signals. Imagine your body's volume knob is stuck on maximum. A stimulus that would cause mild discomfort in someone without endo feels like a 9 out of 10 to you. This isn't psychological. It's a measurable change in how your spinal cord and brain process pain. Surgery doesn't fix this. Only nervous system rehabilitation does.

3. The Gut and Microbiome

Your gut bacteria are dramatically different when you have endometriosis. The "good guys" are depleted, and dysbiotic species thrive. This creates a leaky gut, which lets bacterial lipopolysaccharides (LPS) into your bloodstream—triggering more systemic inflammation. It's a vicious cycle: endo causes dysbiosis, dysbiosis worsens endo. This is why your IBS symptoms might have shown up around the same time as your period pain. They're probably connected.

4. The Hormonal System (Progesterone Resistance)

Women with endometriosis have "progesterone-resistant" endometrial tissue. Progesterone is supposed to tell your uterine lining: "calm down, don't proliferate, don't bleed heavily." But in endo, the tissue doesn't listen. The progesterone receptor is either not expressed properly or mutated. This is why birth control sometimes doesn't work—you're not treating the underlying resistance, just adding more hormones to a system that won't respond to them.

5. The Pelvic Floor Muscles

Chronic pain causes muscle guarding—your pelvic floor tightens to protect against pain signals. But then that tension creates more pain, more guarding, and you're trapped. Adhesions from endo physically restrict muscle movement. Add central sensitization on top, and your pelvic floor becomes hypertonic (perpetually tight), contributing to sexual pain, urinary urgency, and even more gut dysfunction.

6. Sexual Health and Pelvic Function

Dyspareunia (painful intercourse) affects up to 50% of people with endometriosis. It's not just about the lesions being in the wrong place during penetration. It's also the pelvic floor tightness, the visceral hypersensitivity, the anxiety around sex triggering pain. And then there's the shame—the silent devastation of not being able to be intimate with your partner. We don't talk about this enough in the clinic, which is exactly why it festers.

The Accelerated Aging Model

Here's something many clinicians don't explain: endometriosis is associated with accelerated cellular aging. Two mechanisms matter here.

mTOR Dysregulation: mTOR is a cellular "growth switch." In endo, this pathway is overactive, meaning your endo tissue is growing faster than it should. But this also triggers cellular stress and aging pathways. It's like your cells are running a marathon when they should be jogging.

NLRP3 Inflammasome Activation: This is a molecular complex that, when activated, unleashes IL-1β and IL-18—potent inflammatory molecules. Emerging research suggests the NLRP3 inflammasome is hyperactive in endometriosis, driving both local and systemic inflammation. This might explain why some people with endo have elevated inflammatory markers that don't match their imaging findings.

The takeaway: Your cells are aging faster, and your inflammation is deeper than a pelvic ultrasound can see.

Why Surgery Alone Isn't Enough

I've had two excision surgeries. They helped. But they didn't fix my dysbiosis, my nervous system sensitization, or my progesterone resistance.

A skilled excision surgeon can remove the visible lesions—and that matters. But they cannot normalize your immune system. They cannot rewire your central nervous system. They cannot restore your microbiome. They cannot fix progesterone resistance. They cannot undo years of pelvic floor guarding.

Surgery is one tool. Often a necessary one. But endometriosis is a multi-system disease, and it requires a multi-system approach. This is why the best outcomes I've seen come from combining surgical excellence with nutritional medicine, nervous system regulation, pelvic floor therapy, and immunological support.

How Common Is This, Really?

The prevalence of endometriosis is estimated at 1 in 10 women of reproductive age. But that's likely an underestimate—it depends on whether we're counting only diagnosed cases or including the millions of people living with undiagnosed, undertreated disease.

What's undeniable: millions of people are suffering in silence while being told their pain is normal.

What Changes When You Really Understand This

Understanding endometriosis at this level—as a systemic, multi-system disease—changes everything about how you approach your own care.

It means you're not "just" a gynecology patient. You're a patient with systemic inflammation, nervous system dysregulation, and immune dysfunction. This is why your gastroenterologist needs to understand your endo. Why your pain management specialist needs to address central sensitization. Why your pelvic floor therapist is not optional. Why your nutritionist isn't a nice-to-have—it's essential medicine.

It also means you stop blaming yourself. You're not weak. You're not dramatic. You're not "just" dealing with bad periods. Your body is dealing with a multi-system inflammatory disease, and it's doing its best to survive it.

You deserve care that sees all of you. That connects the dots between your symptoms. That treats the whole system, not just the pelvis.

That's what we're building here at Luteal Health. Not another "endo surgery recovery" program. But a complete reimagining of what endometriosis care looks like when you actually treat it as the systemic disease it is.