What Else Could It Be? Ruling Out Other Causes

Pelvic pain that flares with your cycle can feel like a giant neon sign pointing to endometriosis. And sometimes it is. But many people discover—often after months or years of “maybe endo?” appointments—that the real answer is more complicated: endometriosis may be only part of the picture, or something else entirely.

This matters because treatment choices depend on what’s actually driving your symptoms. Hormonal suppression may help one cause, physical therapy may help another, and surgery may not help at all if the main generator is bladder pain, pelvic floor overactivity, or centralized pain processing.

This post pulls together findings from multiple recent reviews and clinical papers on chronic pelvic pain to help you understand the differential diagnosis—the process of ruling conditions in and out—so you can have clearer, more productive conversations with your clinician.

First: “Is this primary dysmenorrhea, or secondary dysmenorrhea?”

A useful starting point is separating primary dysmenorrhea (period pain without pelvic disease) from secondary dysmenorrhea (period pain caused by an underlying condition). A clinical overview in RBGO Gynecology & Obstetrics describes primary dysmenorrhea as pain that is typically predictable cycle-to-cycle, often worst on days 1–2 of bleeding, and usually lasts hours to a few days. The biology is largely tied to higher prostaglandins, which can drive uterine cramping and reduced uterine blood flow—painful, but not due to endometriosis.

What pushes clinicians to look beyond “primary cramps” and evaluate for endometriosis or other causes? Patterns like:

• pain that starts later (not soon after periods begin),
• symptoms that change or escalate over time,
• pain that lasts outside bleeding days, or
• additional symptoms such as abnormal bleeding or deep pain with sex.

That same overview also gives a practical “checkpoint”: if first-line treatment (typically NSAIDs and/or hormonal contraception) hasn’t helped after about 3 months, it’s reasonable to re-evaluate for secondary causes—endometriosis is often top of the list, but it’s not the only one.

Why “endometriosis symptoms” aren’t specific

One reason diagnosis takes so long is that the symptom set—pelvic pain, painful periods, pain with sex, bowel/bladder discomfort, fatigue—overlaps with many conditions. A broad review on chronic pelvic pain in the International Journal of Women’s Health emphasizes that chronic pelvic pain is frequently multifactorial (overlapping contributors are common), and a substantial minority of patients may have no single clear pelvic disease identified. That doesn’t mean the pain isn’t real—it means the body can generate persistent pain through multiple pathways.

The same review highlights an important concept if you’ve had treatment but still hurt: pain can become partly neuropathic or nociplastic (often discussed as central sensitization). In that situation, removing or suppressing a lesion may not fully turn off the pain system. This is one reason “I treated the endo but the pain stayed” is a real and recognized experience—not a personal failure and not “in your head.”

Common endometriosis “look-alikes” (and frequent co-travelers)

Bladder pain syndrome (IC/BPS): when pelvic pain is also a bladder condition

If you have pelvic pain plus urinary urgency/frequency, pain with bladder filling, or burning discomfort—especially when endometriosis treatment hasn’t fully helped—interstitial cystitis/bladder pain syndrome (IC/BPS) deserves consideration.

A 2024 systematic review and meta-analysis in Healthcare found reported overlap between endometriosis and IC/BPS ranging widely across chronic pelvic pain studies (partly because clinics define and test differently). Even with mixed pooled statistics, the overall message is consistent: coexistence is common enough that it should be on the radar, particularly in persistent or “refractory” pelvic pain.

A 2025 clinical consensus in Neurourology and Urodynamics reinforces a key point patients often get told incorrectly: finding endometriosis does not rule out IC/BPS, and “classic endometriosis symptoms” are not enough to distinguish the two. The consensus also notes something many patients find validating: some people can have IC/BPS-type findings even without obvious urinary symptoms, and bladder pain can still worsen around periods—so cycle linkage doesn’t automatically mean the bladder is innocent.

What this means in practice: if you’ve done hormonal therapy or surgery for suspected/known endometriosis and bladder symptoms persist, it’s reasonable to ask for a bladder-focused evaluation (often with urology/urogynecology involvement) rather than assuming “the endo must be back.”

Adenomyosis: similar symptoms, different “home base”

Adenomyosis can mimic endometriosis because it often causes heavy bleeding, severe cramping, and pelvic pressure, but the tissue is located within the uterine muscle rather than outside the uterus. In dysmenorrhea guidance, adenomyosis is explicitly listed among key causes of secondary dysmenorrhea, alongside endometriosis.

Emerging biology research (for example, a 2025 paper in mSystems) suggests adenomyosis and endometriosis may share some inflammatory/metabolic features while also showing distinct tissue signatures. For patients, the take-home isn’t that there’s a new test you can order tomorrow—there isn’t—but that “endo-like” symptoms can come from different underlying processes, and it can be reasonable to discuss adenomyosis explicitly when symptoms include heavy bleeding, an enlarged/tender uterus on exam, or ultrasound features that raise suspicion.

Pelvic congestion syndrome (PCS): pelvic varicose veins and aching pain

Pelvic congestion syndrome is often described as pelvic pain related to dilated pelvic veins. It can overlap with endometriosis-like symptoms and is sometimes missed.

A 2018 systematic review in Acta Obstetricia et Gynecologica Scandinavica found that certain ultrasound findings (like pelvic varicoceles) showed high sensitivity in small studies, while other signs (like a vein >5 mm crossing the uterine body) were highly specific but not sensitive—meaning if it’s present it can support PCS, but if it’s absent you still might not be in the clear. MRI-based approaches sometimes looked sensitive too, but specificities could be modest, raising the risk of false positives.

Practical implication: imaging can be part of the work-up, but PCS is rarely a “one scan = definite answer” situation. If your pain is worse after standing, worse later in the day, or associated with pelvic heaviness, it’s reasonable to ask your clinician whether PCS belongs in your differential—and what imaging in your setting is actually good at detecting it.

Pelvic floor overactivity and vulvar pain: when muscles and nerves become pain generators

The 2025 IC/BPS gynecologic consensus emphasizes that pelvic pain often involves overlapping findings such as overactive pelvic floor muscles, vulvar pain/vestibulodynia, and sexual pain conditions. These are not “either/or” with endometriosis. They can be consequences of long-term pain, separate diagnoses, or both.

This is one reason why pelvic floor physical therapy can be part of a comprehensive plan even while the diagnostic process continues.

GI conditions (like IBS): common overlap, similar symptoms

Even though the papers you’re reading here focus more heavily on gynecologic and bladder drivers, chronic pelvic pain research repeatedly notes overlap with bowel-related pain syndromes and other chronic pain conditions. The 2024 IC/BPS–endometriosis review reports higher rates of conditions like IBS and fibromyalgia in people with coexisting pain diagnoses, supporting what many patients experience: bloating, constipation/diarrhea, and bowel pain can be part of the pelvic pain puzzle.

If your “endo symptoms” are strongly bowel-patterned—pain relieved by bowel movements, major stool changes, food-triggered flares—it’s reasonable to ask whether you need parallel GI evaluation, not as a dismissal of endometriosis, but as part of ruling in/out multiple contributors.

PID (pelvic inflammatory disease): not always an STI story

PID is another potential mimic for pelvic pain, and it’s often thought of as purely STI-related. A 2025 review in Microorganisms highlights that PID can also involve non‑STI microorganisms with different clinical patterns. For patients, the relevance is simple: if symptoms include fever, significant new discharge, cervical motion tenderness, or acute worsening pain—especially with risk factors—PID belongs on the “rule out urgently” list, even if STI testing is negative.

How clinicians actually “rule things out” (and why it can feel slow)

Many patients expect one definitive test. But for endometriosis and most pelvic pain conditions, medicine is still largely a combination of pattern recognition + targeted testing + response to treatment.

A 2019 paper describing how a specialized endometriosis center structures evaluation shows what thorough work-up can look like: standardized symptom history and questionnaires, focused pelvic ultrasound, and selective use of additional imaging/tests (for example, MRI in specific scenarios). Importantly, that paper underscores that ultrasound can help identify certain findings (like endometriomas or signs that suggest adenomyosis), but a normal ultrasound doesn’t rule out endometriosis, especially superficial disease.

That same “center model” also hints at why patients can feel whiplash: in a surgical subgroup already selected because suspicion was high, endometriosis was confirmed in a large majority. That does not mean surgery is the right next step for everyone; it means careful selection matters, and your clinician should be weighing alternative diagnoses and overlapping pain drivers at the same time.

If you’re seeing “new blood test” headlines, here’s the reality

It’s true that researchers are hunting for noninvasive diagnostics. A 2023 review in Biomedicines summarizes proteomics work (protein patterns in blood, peritoneal fluid, tissue, and more) in endometriosis and adenomyosis. And the 2025 mSystems study reports striking separation of groups using endometrial metabolite and microbiome signatures.

But across these papers, the common thread is that this work is early-stage: promising for future panels, not something most clinics can use today to definitively rule in/out endometriosis, adenomyosis, or overlapping bladder pain. If you’ve felt misled by simplified headlines, you’re not alone—the biology is complex, and any eventual test will likely be a validated multi-marker panel, not one magic molecule.

Practical takeaways: how to talk about “what else could it be?”

Use your visit time to make the differential diagnosis explicit. You’re not asking your clinician to “guess better”—you’re asking them to show their reasoning and plan.

Here are questions that tend to move the conversation forward:

• “Based on my symptom pattern, what are the top 3 diagnoses you’re considering besides endometriosis—for example adenomyosis, IC/BPS, IBS, pelvic floor dysfunction, or pelvic congestion syndrome?”
• “What findings would make you more suspicious for a bladder pain syndrome, and what would evaluation look like?”
• “Does my bleeding pattern and uterine exam/imaging raise concern for adenomyosis?”
• “Are there signs of pelvic floor overactivity on exam—and would pelvic floor PT be appropriate while we continue the work-up?”
• “If we try NSAIDs/hormonal treatment, what’s our timeline to reassess and what’s the next step if I’m not better?” (Some dysmenorrhea guidance suggests re-evaluating after about 3 months if symptoms don’t improve.)
• “Before considering major surgery, what other pain generators do we need to assess so we don’t miss a coexisting cause?”

What we still don’t know (and why your journey can be long)

Even the best evidence agrees on a frustrating truth: chronic pelvic pain isn’t one disease. Studies show wide variability in comorbidity rates (like endometriosis with IC/BPS), and imaging criteria for conditions like PCS are not fully standardized. Biomarker research is exciting, but not yet ready to replace careful clinical evaluation.

The most important unknown is often individual: which combination of drivers is operating in your body right now—uterine (adenomyosis), extrauterine (endometriosis), bladder (IC/BPS), bowel (IBS-like), muscular (pelvic floor), vascular (PCS), inflammatory/infectious (PID), or pain-processing (central sensitization). Many people have more than one.

If you take one thing from this post, let it be this: asking “what else could it be?” is not doubting yourself or abandoning the possibility of endometriosis. It’s a skilled, evidence-based move—one that can shorten the trial-and-error loop and get you closer to a plan that actually helps.