Pelvic Pain in Women: Endometriosis vs. Interstitial Cystitis - How to Tell Them Apart

Chronic pelvic pain in women is often dismissed as "just bad periods" or "stress." But for millions, it’s a daily battle - burning urination, aching deep in the pelvis, pain during sex, and the constant need to rush to the bathroom. Two conditions, endometriosis and interstitial cystitis, are behind most of these cases. They look alike. They feel alike. And too often, doctors treat one while missing the other.

What You’re Really Feeling

If you’ve had pelvic pain for more than six months, and tests keep coming back "normal," you’re not imagining it. Endometriosis happens when tissue like the uterine lining grows outside the uterus - on the ovaries, bowel, bladder, or even the diaphragm. It bleeds and swells with your cycle, causing inflammation and scar tissue. Interstitial cystitis (IC), also called painful bladder syndrome, is a chronic bladder condition where the lining breaks down, letting urine irritate the bladder wall. No infection. No tumor. Just pain.

Both cause:

• Pain during sex (dyspareunia)
• Frequent urination (more than 7 times a day)
• Urgency - the sudden, uncontrollable need to go
• Lower abdominal or pelvic pressure
• Pain that gets worse with certain foods or stress

But here’s the key difference: endometriosis pain follows your period. It spikes before or during menstruation, then eases. IC pain? It’s more constant. It might flare around your period, but it doesn’t disappear. If your pain is tied to your cycle, endometriosis is likely involved. If your bladder is the main problem - and your pain doesn’t change with your period - IC is more probable.

Why Misdiagnosis Is So Common

A 2011 study of 178 women with chronic pelvic pain found that 65% had both conditions. That’s not rare - it’s the norm. Yet most doctors still look for one or the other. Why? Because endometriosis needs surgery to confirm. IC has no blood test or scan. It’s a diagnosis of exclusion - meaning you have to rule out everything else first.

That’s a long, frustrating road. Most women see 4-6 doctors over 7-10 years before getting the right diagnosis for endometriosis. For IC, it’s 3-5 years. Many are told they have recurrent UTIs and given antibiotics for years - even though urine cultures are always clean. One Reddit user, after nine years of misdiagnosis, finally had laparoscopic surgery that revealed stage IV endometriosis on her bladder wall. Her urinary symptoms improved by 80% after the lesions were removed.

And here’s the hard truth: up to 80% of women diagnosed with IC actually have undiagnosed endometriosis, according to urologists at Hofstra Northwell. Many bladder lesions from endometriosis are invisible on ultrasound or MRI. Only a skilled surgeon using laparoscopy can see them - and even then, they’re often missed if the surgeon isn’t trained in deep excision.

How Diagnosis Really Works

There’s no shortcut. But there is a smarter path.

For endometriosis: The only reliable way to confirm it is through laparoscopic surgery with biopsy. This isn’t a simple procedure. It requires a surgeon trained in excision - not just ablation. General OB/GYNs rarely have this skill. Only 15% of U.S. OB/GYNs are proficient. The surgery costs $5,000-$15,000 and needs 2-4 weeks to recover. But without it, you’re guessing.

For interstitial cystitis: Diagnosis starts with ruling out infections, cancer, and sexually transmitted diseases. Then comes cystoscopy - a camera inserted into the bladder. If you have IC, the bladder wall may show Hunner’s ulcers (small sores) or glomerulations (tiny bleeding spots). A Potassium Sensitivity Test (PST) can help - if your bladder hurts badly when exposed to potassium solution, it’s a sign the lining is damaged. But PST has a 20% false negative rate. It’s not perfect.

There’s also the PUF scale - a questionnaire that asks about pain, frequency, and urgency. A score of 8 or higher suggests IC. But if you have both conditions, the PUF score can be misleading. That’s why experts now say: never diagnose IC without first ruling out endometriosis.

The Overlooked Link: Pelvic Floor Dysfunction

Here’s something rarely discussed: 92% of women with either endometriosis or IC also have pelvic floor muscle spasms. These muscles tighten up in response to pain - and then become a source of pain themselves. It’s a loop: pain → muscle tension → more pain.

Physical therapy focused on pelvic floor relaxation can help - but only if the root cause is treated. If you’re doing Kegels or stretching without addressing endometriosis lesions or bladder inflammation, you’re just managing symptoms. You’re not healing.

That’s why a multidisciplinary approach is critical. You need a gynecologist who does excision surgery, a urologist or urogynecologist who understands IC, and a pelvic floor physical therapist - all working together.

What Treatment Actually Works

Treatments for these conditions are wildly different - and mixing them up can make things worse.

Endometriosis treatment: Excision surgery is the gold standard. Removing the lesions - not just burning them - leads to long-term pain relief in 70-80% of cases. Hormonal therapies like birth control or GnRH agonists can help manage symptoms, but they don’t remove the disease. If you have bladder endometriosis, surgery may resolve your urinary symptoms entirely.

IC treatment: Dietary changes (avoiding caffeine, alcohol, citrus, spicy foods) help about 60% of patients. Bladder instillations - solutions like DMSO or heparin put directly into the bladder - can repair the lining. Oral meds like pentosan polysulfate sodium (Elmiron) were once standard, but recent studies show it can cause retinal damage after long-term use. Newer options like amitriptyline (an antidepressant used for nerve pain) or nerve stimulation (like InterStim) are gaining traction.

But here’s the biggest mistake: giving IC meds to someone with endometriosis. It won’t work. And delaying surgery for endometriosis means more scar tissue, more pain, and more damage to organs.

Why You Need to Push Back

You’re not being difficult if you ask for more testing. You’re being smart.

76% of IC patients report being told their pain is "all in their head." Black women wait an average of 11.7 years for an endometriosis diagnosis - nearly four years longer than white women. Insurance often denies cystoscopy or laparoscopy the first time. You may need to appeal.

Here’s what to say to your doctor:

• "I’ve had pain for over six months. I need a full pelvic exam and a referral to a specialist in endometriosis excision."
• "I’ve had clean urine cultures but still have bladder pain. Can I get a cystoscopy and Potassium Sensitivity Test?"
• "I’ve been told I have IC, but my pain gets worse with my period. Could I also have endometriosis?"

Don’t accept a diagnosis based on symptoms alone. Demand a plan. If your doctor won’t refer you to a specialist, go to the Endometriosis Foundation or Interstitial Cystitis Network - they have directories of trained providers.

What’s Changing in 2026

The medical world is finally waking up. In January 2024, the Endometriosis Foundation updated its surgical guidelines to require bladder evaluation during every excision surgery. In February 2024, the NIH gave $4.2 million to find biomarkers that can distinguish endometriosis from IC without surgery. And by 2030, experts predict multidisciplinary pelvic pain clinics - where gynecologists, urologists, and physical therapists work in the same room - will become the standard.

For now, you’re on your own. But you’re not alone. Over 190 million women worldwide have endometriosis. Millions more have IC. You’re not crazy. You’re not broken. You just haven’t found the right care yet.

If you’ve been told your pain is "normal," or you’ve been passed from doctor to doctor for years - your pain matters. And there is a path forward. It’s not easy. But it’s possible.