If Not Endometriosis, Then What Could It Be?

Chronic pelvic pain has a long list of possible causes beyond endometriosis, spanning gynecological, urological, gastrointestinal, musculoskeletal, vascular, and neurological conditions. When laparoscopy comes back clean, when hormonal treatment fails, or when a confirmed case of endometriosis has been treated but the pain persists, the answer often lies in one or more of these overlapping disorders. An expert consensus panel noted that chronic pelvic pain frequently occurs secondary to nongynecologic conditions that must be considered in the evaluation of affected women.¹ Getting the right diagnosis can be a frustrating journey, but the possibilities are more concrete than most people realize.

Adenomyosis

Adenomyosis is probably the condition most commonly confused with endometriosis, and for good reason. While endometriosis involves tissue resembling the uterine lining growing outside the uterus, adenomyosis involves endometrial glands and surrounding tissue burrowing into the muscular wall of the uterus itself, causing that muscle to thicken. The symptoms look almost identical: painful periods, heavy bleeding, and deep aching pain. Adenomyosis can appear as a diffuse process throughout the uterine wall, as focal patches, or as a distinct mass called an adenomyoma.²

Making matters more confusing, adenomyosis and endometriosis frequently coexist in the same person, which means diagnosing one does not rule out the other. Adenomyosis has historically been a diagnosis confirmed only after hysterectomy, but MRI and high-quality transvaginal ultrasound have improved detection significantly. If you have been told your laparoscopy was negative for endometriosis but your periods are still brutal, adenomyosis deserves a hard look.

Uterine Fibroids

Fibroids are noncancerous growths in the uterine muscle, and they are extremely common. Depending on the population studied and how they are detected, lifetime prevalence ranges from roughly 40% to nearly 90%.³ Many people with fibroids have no symptoms at all. But among those who do, the pattern can overlap with endometriosis. In a survey of 3,000 people with fibroids, about three-quarters reported painful periods, a third reported pelvic pain outside of menstruation, and nearly 30% reported pain during sex.³

A population-based study found that women with fibroids had roughly two to three times the odds of reporting moderate or severe pain during sex and moderate or severe noncyclic pelvic pain compared to women without fibroids.⁴ The location of a fibroid matters more than its size for predicting symptoms, which is one reason imaging alone does not always tell the full story. Fibroids pressing on the bladder, bowel, or pelvic nerves can mimic a range of non-uterine problems.

Pelvic Congestion Syndrome and Vascular Compression

Pelvic congestion syndrome is one of the more under-recognized causes of chronic pelvic pain, particularly in people of reproductive age. The underlying problem is pelvic venous insufficiency, where blood flows backward through the gonadal or internal iliac veins, leading to enlarged, varicose-like veins in the pelvis. The hallmark symptom is a dull, aching pain that worsens when you are upright or standing for long periods and improves when you lie down. It is also commonly associated with visible varicose veins on the vulva or inner thighs and with pain during or after sex.⁵

In some cases, the venous congestion is caused by a structural compression problem. May-Thurner syndrome involves the left iliac vein being compressed by the overlying right iliac artery. Nutcracker syndrome involves the left renal vein being compressed between the aorta and the superior mesenteric artery. Both can lead to pelvic congestion. A case series found that patients with chronic pelvic pain who had failed other treatments were ultimately diagnosed with pelvic congestion secondary to one or both of these compression syndromes.⁶ Diagnosis typically requires specialized vascular imaging, such as CT venography or MR venography, that is not part of a standard pelvic pain workup. If your pain is distinctly positional, this possibility is worth raising with your doctor.⁷

Interstitial Cystitis and Painful Bladder Syndrome

Interstitial cystitis, sometimes called painful bladder syndrome, causes bladder pressure, bladder pain, and sometimes pelvic pain that can feel almost indistinguishable from endometriosis. The overlap between the two is well documented. A review of the evidence concluded that patients presenting with symptoms typically blamed on endometriosis, or whose pain persists after endometriosis treatment, may in fact have interstitial cystitis, and that the two conditions can even coexist in the same person.⁸

Key distinguishing features to watch for include urinary urgency and frequency, pain that worsens as the bladder fills and eases after urination, and pain centered more in the suprapubic (low-center) region. But many people with interstitial cystitis do not have these textbook symptoms, and the condition lacks a single definitive diagnostic test, which helps explain why it gets missed. If your pelvic pain never fully responded to endometriosis-focused treatments, a bladder-oriented evaluation could uncover this as a contributing factor.

Irritable Bowel Syndrome and Other GI Causes

The gut is a major player in chronic pelvic pain, and irritable bowel syndrome is the most common gastrointestinal culprit. A population-based study found that the overlap between IBS and chronic pelvic pain was about twice as high as would be expected by chance alone.⁹ Bloating, cramping, constipation, diarrhea, and low abdominal pain that fluctuates with bowel habits can easily be mistaken for the cyclical symptoms of endometriosis, especially when bowel symptoms worsen around menstruation (as they often do).

Research on pelvic nerve pathways suggests that IBS, interstitial cystitis, and other chronic pelvic pain disorders frequently appear together because the nerves serving pelvic organs converge and cross-talk. Irritation of one organ can sensitize another through this shared wiring.¹⁰ This means that a primary bowel problem can create bladder symptoms and vice versa, making it even harder to pin down the original source.

Inflammatory bowel diseases like Crohn’s disease can also generate pelvic pain, though this gets less attention. The transmural inflammation characteristic of Crohn’s can affect any part of the GI tract, and when it involves the lower intestine or rectum, pelvic pain is a common result. Most pain research in Crohn’s has focused on abdominal pain, leaving pelvic pain relatively understudied despite being a frequent complaint.¹¹

Pelvic Floor Muscle Dysfunction

The pelvic floor is a group of muscles spanning the base of the pelvis, supporting the bladder, uterus, and rectum. When these muscles become chronically tight, weak, or develop trigger points, they can produce pain that mimics organ-based conditions. Overactive pelvic floor muscles can create symptoms that feel like a bladder infection, bowel disease, or deep gynecological pain. Research has shown that active trigger points in internal and external pelvic muscles can cause, aggravate, or maintain chronic symptoms involving the bladder, urethra, and lower bowel, and that deactivating those trigger points can improve or eliminate both the functional symptoms and the associated pain.¹²

What makes pelvic floor dysfunction particularly tricky is that it often develops as a secondary response to another condition. Years of pain from endometriosis, a bladder condition, or even chronic stress can cause the pelvic floor muscles to guard and tighten. The primary condition may then resolve or be treated, but the muscle dysfunction persists as an independent pain generator. This is one of the most common reasons people continue to have pelvic pain after successful endometriosis surgery. A review of the interplay between pelvic organs and muscles described how signals from irritated organs can produce muscle overactivity, and how that muscle overactivity can, in turn, feed signals back to the organs, creating a self-reinforcing cycle.¹³

Pudendal Neuralgia and Other Nerve Problems

The pudendal nerve runs through the pelvis and supplies sensation to the perineum, genitals, and lower rectum. When it becomes compressed or irritated, the result is pudendal neuralgia: burning, stabbing, or electric-shock-like pain that is typically on one side and gets worse with sitting. Many of the conditions that cause chronic pelvic pain are located in the area served by the pudendal nerve, which is why pudendal nerve blocks have been used successfully to help control pain symptoms across several different pelvic pain diagnoses.¹⁴

Other nerves in the region can be involved too. The ilioinguinal, iliohypogastric, and genitofemoral nerves can become entrapped after surgery (including cesarean sections and hernia repairs) or due to scar tissue. Nerve-related pelvic pain tends to have a distinctive quality: sharper, more burning or electric, and often worsened by specific positions or activities. If your pain has this character and has not responded to hormonal or organ-targeted treatments, a neuropelvic evaluation could be informative.

Central Sensitization and Overlapping Pain Conditions

One of the most important and least intuitive concepts in chronic pelvic pain is central sensitization. Over time, sustained pain signals from the pelvis can change how the brain and spinal cord process pain, effectively turning up the volume on the nervous system’s alarm system. Research shows that women with chronic pelvic pain display increased sensitivity to painful stimuli, likely reflecting changes in the central nervous system rather than ongoing damage at the site of the original problem.¹⁵

This helps explain a frustrating clinical pattern: even after surgically removing all visible endometriosis, pain sometimes continues or worsens. The original tissue problem may be gone, but the nervous system has learned to amplify pain signals. Researchers have identified that people who score high on measures of central sensitization show a systemic failure of the body’s normal pain-dampening pathways, suggesting a “software” problem in pain processing rather than a “hardware” problem at a specific organ.¹⁶

Central sensitization also helps explain why chronic pelvic pain so often travels with other pain conditions. A cross-sectional survey found that a quarter of women with endometriosis reported three or more overlapping pain conditions, compared to about 12% of those without endometriosis. Fibromyalgia, chronic fatigue syndrome, and temporomandibular disorders were all significantly more common in the endometriosis group. Critically, the number of overlapping conditions predicted worse pain severity and interference regardless of whether endometriosis was present.¹⁷ In other words, if you have multiple pain conditions layered on top of each other, those layers are probably making each other worse through shared nervous system pathways.

Pelvic Inflammatory Disease and Its Aftermath

Pelvic inflammatory disease is an infection of the upper reproductive tract, usually caused by sexually transmitted bacteria. Acute PID can cause fever, discharge, and severe pain, but the connection to chronic pelvic pain is more about what PID leaves behind than the infection itself. Scarring, adhesions, and chronic low-grade inflammation following one or more episodes of PID can produce persistent pain long after the initial infection has cleared.

A study of predictors for chronic pelvic pain among women with signs of PID found that having two or more prior PID episodes nearly tripled the odds of developing chronic pain. Interestingly, the study also found that a low mental health score independently predicted chronic pelvic pain after PID, with nearly three times the odds.¹⁸ This points to the broader pattern that chronic pelvic pain is rarely about a single organ or a single cause.

Hypermobility and Connective Tissue Disorders

People with hypermobile joints have an increased risk of developing pelvic girdle pain, which refers to musculoskeletal pain localized to the pelvic ring at the front, back, or both. This connection is particularly relevant for people with hypermobility spectrum disorder or the hypermobile type of Ehlers-Danlos syndrome.¹⁹ Among women presenting specifically with chronic myofascial pelvic pain, the estimated prevalence of generalized hypermobility was higher than in the general population, with significant associations to several other comorbid conditions.²⁰

If you already know you are “bendy,” or if you have a history of joint dislocations, easy bruising, stretchy skin, or chronic joint pain alongside your pelvic symptoms, the connective tissue component is worth evaluating. The lax ligaments that characterize hypermobility can allow the pelvic joints to shift more than they should, stressing muscles and nerves in the area. These patients often benefit from targeted pelvic physical therapy but can worsen with generic stretching protocols, which makes an accurate diagnosis especially important.

The Role of Childhood Trauma and Psychological Factors

This is a topic that requires careful framing. Saying that psychological factors contribute to chronic pelvic pain is not the same as saying the pain is imaginary. The relationship between trauma and chronic pain is biological, not imagined. A study of women with chronic pelvic pain found they had more than three times the odds of reporting four or more adverse childhood experiences compared to a control group. Over half the chronic pelvic pain group had experienced childhood sexual abuse, and 43% reported physical abuse, both significantly higher rates than in the control group.²¹

Research into the mechanism connecting trauma to pain sensitivity found that childhood violent trauma, both sexual and nonsexual, was significantly associated with increased pain sensitivity in the pelvic region. The primary pathway through which this occurred was generalized sensory sensitivity, meaning the nervous system becomes more reactive to painful stimuli across the body, not just at the site of the original harm.²² Another study found that emotional neglect was reported more often in women with chronic pelvic pain than in healthy women, and that childhood maltreatment scores correlated directly with anxiety and depression levels.²³

None of this means that trauma “causes” pelvic pain in a simple, one-directional way. But it does mean that if your pain has been resistant to every organ-specific treatment, screening for trauma history and addressing psychological contributors alongside physical ones could be a missing piece. Treatments like trauma-informed therapy, pain neuroscience education, and mind-body approaches are not alternatives to medical care; they work best as additions to it.

When Doctors Do Not Believe You

It would be incomplete to discuss the differential diagnosis of pelvic pain without acknowledging the reality of the diagnostic experience. The average time from symptom onset to an endometriosis diagnosis is well documented to span many years, but the delays are not unique to endometriosis. Any condition on this list can take years to identify, partly because they overlap, partly because some require specialized imaging or testing, and partly because of how often pelvic pain is dismissed.

A large survey of patients with vulvovaginal disorders found that over half had considered stopping medical care entirely, either because their concerns were not being addressed or because they felt no practitioner could help them. Patients rated their distress at being made to feel “crazy” by a provider at a mean of about 7.4 out of 10. The emotional harms described included general distress and a pervasive sense of futility.²⁴ Although that study focused on vulvovaginal conditions specifically, the pattern is familiar across the full spectrum of chronic pelvic pain.

If you have been told your imaging is normal and therefore nothing is wrong, that framing misunderstands what normal imaging means. Many of the conditions discussed here, from pelvic floor dysfunction to interstitial cystitis to central sensitization, do not show up on a standard ultrasound or even a basic MRI. A normal scan rules out some possibilities but opens the door to others. Seeking out a pelvic pain specialist, a pelvic floor physical therapist, or a multidisciplinary pain center often proves more productive than cycling through generalists who each look at the pelvis through only one lens.

Practical Steps When You Are Stuck

If you are at the stage where endometriosis has been ruled out or treated and pain persists, a few practical moves can help narrow the field. Keeping a pain diary that tracks not just timing and severity but also position (worse standing? sitting? lying down?), relationship to meals, bladder habits, and bowel patterns can reveal patterns pointing toward vascular, GI, urological, or musculoskeletal causes. Noting whether pain is one-sided is also useful, since pudendal neuralgia and certain nerve entrapments tend to be unilateral.

A comprehensive evaluation by a specialist or multidisciplinary team can be structured to include pelvic floor assessment, bladder testing, musculoskeletal exam of the pelvic girdle and hip, and appropriate vascular imaging if positional symptoms suggest congestion. Diet and lifestyle modifications, physical therapy, biofeedback, medications, and procedures like nerve blocks can all be used alone or in combination, individualized to what the evaluation reveals.¹⁴ The evidence strongly favors approaching chronic pelvic pain as a condition with multiple contributors rather than a single culprit waiting to be found.