Endometriosis Excision: What Are Systemic Causes of Pain After Surgery?

Endometriosis excision surgery is in your rear-view mirror, and you were hoping it was heading into the past. Yet—you still hurt. Sometimes the pain is the same. Sometimes it’s different: burning at the vaginal opening, pain with sex, widespread aching, flares that feel allergic or inflammatory, or a body that seems stuck in “high alert,” yet fatigued.

This primer, and part of our series covering "Why Do I Still Hurt?", focuses on one specific set of reasons pain can persist after endometriosis surgery: systemic and immune–nerve factors that can keep pain circuits activated even when visible disease is treated. I’m drawing here from multiple recent research reviews plus a mechanistic study in humans and mice that together paint a consistent theme: for some people, pain is driven not only by lesions, but by neuro-immune signaling (immune cells talking to nerves), hormonal influences, and overlapping conditions like vulvodynia and other chronic pain syndromes.

This is not about blaming pain on one thing or another under a general theme of “stress." It’s about expanding the map—so you and your care team can investigate what else might be contributing.

First: is this “autoimmune,” “systemic,” or something else?

Patients often use “autoimmune” as shorthand for “my immune system is overreacting.” True autoimmune diseases involve the immune system attacking the body’s own tissues in a specific way (and they have their own diagnostic criteria and treatments). Endometriosis itself is usually described as inflammatory and immune-influenced, not classically autoimmune.

What matters for persistent pain after surgery is that research increasingly supports a neuroendocrine–immune model: hormones, immune cells, and nerves form feedback loops that can maintain pain even after a good operation. Reviews focused on endometriosis-associated pain describe inflammatory mediators (like IL-1β, IL-6, TNF-α, prostaglandins, and neurotrophins such as NGF/BDNF) alongside structural nerve changes in and around lesions—changes that correlate with pain more consistently than “endometriosis stage” does.

So if you’re still in pain, one important question becomes:

Is my pain being maintained by an ongoing “immune + nerve sensitization” loop, by overlapping pain conditions, or by a body-wide dysregulation pattern (like dysautonomia)?

Mast cells: why allergy-type immune cells keep showing up in pain research

Mast cells are immune cells best known for their role in allergies: they release histamine and many other biochemical mediators. But across multiple lines of evidence, mast cells are also increasingly implicated in chronic pelvic pain biology—including endometriosis and vulvar pain conditions.

What the combined evidence suggests

Across endometriosis-focused reviews, mast cells are repeatedly described as accumulating in lesions and interacting closely with nerves, potentially amplifying pain signaling. One mechanistic study examining human endometriotic lesions found a mast-cell-supportive environment in lesion tissue compared with a patient’s own eutopic endometrium (the normal uterine lining), including higher mast-cell-related markers and higher levels of stem cell factor (SCF)—a key survival/growth signal for mast cells. In that same work, mast-cell-conditioned media drove endometriosis-related epithelial and stromal cells to produce IL-6 and IL-8, suggesting a plausible “two-way conversation” where mast cells increase inflammation and inflamed tissue further recruits/activates mast cells.

Recent reviews go a step further and propose a specific pain mechanism: mast cell mediators (especially histamine) may sensitize peripheral pain nerves and contribute to central sensitization (an over-responsive spinal cord/brain pain system). Even more illuminating is that estrogen can activate mast cells through estrogen receptors and related pathways, creating a feed-forward loop: estrogen and inflammation support local estrogen production and mast cell activity, which may worsen pain sensitivity over time.

What this could look like in real life after surgery

If mast-cell-driven signaling is part of your pain picture, you might notice:

• Flare patterns (sudden spikes after triggers)
• Symptoms that feel “inflammatory” or “allergic” (though not always)
• Pain that seems disproportionate to findings on imaging or exam
• Multiple systems involved (skin, GI, bladder, sinuses, headaches)

Important nuance: even the papers that strongly argue mast cells are important also acknowledge a key limitation—we still don’t have endometriosis-specific clinical trials proving that mast-cell-targeting medications reliably reduce endometriosis pain. This is a “promising mechanism,” not a proven treatment pathway yet.

Why pain can persist even when tissue “looks normal”: sensitized nerves and immune cross-talk

A recurring message across pain-focused endometriosis literature is that pain severity often correlates weakly with disease stage. Instead, studies repeatedly link pain to:

• Aberrant innervation (increased sensory nerve fibers in lesions and sometimes altered autonomic nerve patterns)
• Neurotrophins like NGF and BDNF (which can encourage nerve growth and hypersensitivity)
• Ongoing inflammatory signaling that keeps nerves “turned up”

This matters after surgery because removing lesions may reduce one source of inflammation—but if nerve pathways have become sensitized, or if immune signaling remains active, the pain system may continue to fire. In other words: surgery can be necessary and can help quite a bit, but still not be sufficient for every pain driver. This does not mean surgery is or was not something to pursue. It is still a cornerstone of effective treatment in most patients, but not in everyone and not completely. But it is almost impossible to tell if this will be the case or not before surgery. It's a matter of being prepared and doing everything possible to alleviate multiple pain triggers.

Vulvodynia (especially vestibulodynia): a common “overlapping neighbor” to consider

If your post-surgery pain includes burning at the vaginal opening, pain with insertion (tampons, pelvic exams), or pain with penetration that feels more like surface burning/sharpness than deep pelvic pressure, it’s worth discussing localized provoked vestibulodynia (LPV) with your clinician.

A 2023 review on vulvodynia highlights a pattern that mirrors endometriosis pain research: immune-and-nerve mechanisms can produce pain that persists even when the tissue looks relatively normal on exam. In summarized clinical and experimental findings, vulvar/vestibular tissues in some patients appear to have an amplified inflammatory response to yeast-related stimuli, and mast cells are repeatedly implicated in biopsies and animal models of persistent vulvar sensitivity—sometimes lasting beyond obvious inflammation.

Why this matters for endometriosis patients

Dyspareunia is often attributed to endometriosis alone, but evidence suggests it can be multifactorial. In a survey study of people with Ehlers–Danlos syndromes (EDS) and hypermobility spectrum disorders (HSD), dyspareunia was very common, and half screened positive for probable vulvodynia using a standardized questionnaire. Many participants also reported endometriosis, underscoring a practical reality: more than one diagnosis may be contributing to pain with sex.

So if you had endometriosis surgery and deep pain improved but entry pain did not—or if pain shifted toward burning at the opening—adding a vulvodynia/vestibulodynia evaluation can be a major missing puzzle piece.

Dysautonomia and “body-wide” amplification: when the autonomic nervous system is involved

The autonomic nervous system (ANS) helps regulate heart rate, blood pressure, digestion, temperature, and “fight/flight” responses. Endometriosis pain reviews discussing autonomic–inflammation interactions propose that inflammation and nerve remodeling may influence sympathetic/parasympathetic signaling in ways that affect pain perception and potentially other symptoms (like bowel/bladder function and global sensitivity). The exact causal pathways remain uncertain, but the pattern—nerves + inflammation moving together—shows up repeatedly.

Some people also live with dysautonomia conditions (such as POTS) that can overlap with chronic pain syndromes. While the papers here don’t specifically review dysautonomia, they support a broader framework: pain can be maintained by system-level regulation issues, not only by local pelvic disease.

Why connective tissue and chronic pain clusters matter (EDS/HSD, fibromyalgia, IC)

Overlapping conditions can change both symptoms and treatment strategy. In the EDS/HSD vulvodynia survey, higher odds of screening positive for vulvodynia were seen alongside other chronic pain comorbidities (for example, fibromyalgia and interstitial cystitis in that sample). This doesn’t prove one causes the other—but it does support a “clustering” reality many patients already live: pelvic pain can sit inside a wider pain and sensitivity landscape.

If you recognize yourself in that—joint hypermobility, widespread pain, bladder pain, TMJ issues, migraines, IBS-type symptoms—it may be a signal to pursue multidisciplinary care rather than putting it all on a failed incomplete surgery or even aggressive recurrent endo.

Treatment implications

Because much of this evidence is mechanistic and review-based, the most useful “next steps” are often better targeting and triage, not a single miracle medication or intervention.

Here are the most practical directions that fit the evidence without overpromising:

• Clarify pain type(s): deep pelvic pain vs entry pain/burning vs bladder pain vs bowel pain vs widespread pain. Different patterns point to different contributors.
• Screen for vulvodynia/vestibulodynia when penetration/tampon pain or vestibular burning is prominent—especially if pelvic imaging/surgery doesn’t explain it.
• Discuss mast-cell pathways carefully: mast cells and histamine are compelling targets in theory, and estrogen–mast cell interactions may matter, but endometriosis-specific trials of antihistamines/mast cell stabilizers were noted as lacking in recent reviews. If you and your clinician consider a trial, frame it as symptom-guided and individualized, not as a proven endometriosis treatment.
• Address nervous system “set point”: the neuroendocrine–immune framework supports interventions that calm sustained threat signaling (pain education, graded activity, sleep optimization, pelvic PT, and—when appropriate—medications for neuropathic pain or centralized pain). These approaches don’t deny biology; they aim to change it.

Practical takeaways: questions to ask your doctor

• “Can we break down my pain into deep pelvic vs entry/vestibular vs bladder/bowel vs widespread components?”
• “Given my symptoms, should we evaluate for vulvodynia/vestibulodynia in addition to endometriosis?”
• “Do my symptoms suggest central sensitization or an overlapping pain condition like IC/BPS or fibromyalgia?”
• “Do I have signs that warrant looking into dysautonomia (for example, lightheadedness, palpitations, heat intolerance) or hypermobility/EDS?”
• “If we suspect immune–nerve amplification, what are our stepwise options—pelvic PT, topical therapies for vestibular pain, neuropathic pain strategies, hormonal options, and (if appropriate) carefully monitored trials of other agents?”

What we still don’t know

The research linking mast cells, estrogen signaling, nerve remodeling, and pain is biologically compelling, and some human tissue studies support it directly. But major gaps remain:

• Many conclusions come from reviews, correlations, and animal models, which can’t perfectly predict individual patient outcomes.
• Even when mast cells are increased in lesions, we still can’t say: “Your mast cells are the reason you hurt” or “this medication will fix it.” The level of increased activity is also critical, as is how and when to accurately test for that.
• Overlapping conditions (vulvodynia, bladder pain, hypermobility, dysautonomia, fibromyalgia) can coexist, making it hard to identify the primary driver without a structured evaluation plan.

Still, the combined evidence supports a validating message: persistent pain after endometriosis surgery doesn’t automatically mean the surgery “failed.” It may mean the pain system is being maintained by system-level immune and nerve biology, and it’s worth expanding the investigation accordingly.

In the next (final) post in this series, we’ll put all of these possibilities—recurrence, adhesions, sensitization, muscle dysfunction, “neighbors,” and systemic overlap—into a step-by-step plan you can take to your care team.