Endometriosis: Symptoms, Causes, and Treatment

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026

Endometriosis is tissue similar to the uterine lining growing outside the uterus.

Quick Answer: What is endometriosis?

Endometriosis is a condition in which tissue similar to the uterine lining grows outside the uterus, most often in the pelvis, and bleeds with each menstrual cycle. [1] [5] The main symptom is pelvic pain beyond normal cramping. [5] Most endometriosis cannot be seen on ultrasound or MRI, and only surgery can confirm it. [1] [3] Treatment starts with pain relievers and hormone therapy. [1] [2]

What the research says

According to PubMed:

• Mifepristone may ease period pain but causes hot flushes. A 2026 Cochrane update of 9 randomized trials (922 women; certainty of evidence low to very low) found that in one study of 360 women, mifepristone versus placebo may improve dysmenorrhoea at 3 months (OR 0.07, 95% CI 0.03 to 0.15) but may increase hot flushes (OR 28.79, 95% CI 3.93 to 210.73). (Grammatis et al., Cochrane Database Syst Rev, 2026, DOI) [6]

• Small unoperated endometriomas appear to have little effect on IVF stimulation. A meta-analysis of 13 observational studies in women with a unilateral ovarian endometrioma found comparable numbers of oocytes retrieved from the affected and unaffected ovary (MD -0.72, 95% CI -1.45 to 0.02; 11 studies, 560 patients), though the number of embryos formed was lower in affected ovaries (MD -0.72, 95% CI -1.39 to -0.05). The impact of larger endometriomas remains uncertain. (Kalaitzopoulos et al., Hum Reprod, 2026, DOI) [7]

Study details are from PubMed abstracts.

Key facts at a glance

Fact	Detail
Pronunciation	Endometriosis (en-doe-me-tree-O-sis)
Where it forms	Ovaries, fallopian tubes, and the tissue lining the pelvis; can involve bowel and bladder [5]
What the tissue does	Thickens, breaks down, and bleeds with each menstrual cycle, but has no way to leave the body
Tissue effects	Irritates surrounding tissue; forms scar tissue and adhesions; can cause ovarian cysts called endometriomas [2] [5]
Pain signal	Pain does not show how much tissue is present; small amounts can hurt badly, and some people have no symptoms [1] [5]
Who it affects	Most commonly people in their reproductive years; symptoms often begin years after periods start
Progression	It is a progressive condition; untreated, pain can spread to times outside the menstrual cycle

Symptoms: pain signals that go beyond normal cramps

Common pain signals of endometriosis.

The main symptom of endometriosis is pelvic pain, often linked with menstrual periods. [5] Many people cramp during their periods, but the pain of endometriosis is usually far worse than usual, and it can grow worse over time. [3]

Symptom	What it looks like
Painful periods	Pelvic pain and cramping that start before a period and last for days into it, often with lower back and stomach pain [1] [5]
Pain with sex	Pain during or after intercourse [3] [5]
Pain with bowel movements or urination	Most likely before or during a menstrual period [3]
Excessive bleeding	Heavy menstrual periods or bleeding between periods [5]
Infertility	Sometimes the condition is first found during infertility testing [5]
Other symptoms	Fatigue, diarrhea, constipation, bloating, or nausea, especially before or during periods

A key point is that the amount of pain does not tell you how much endometriosis tissue is in the body. Someone with a small amount of tissue can have severe pain, while someone with a lot of tissue can have little or none. [1] [5] Some people have no symptoms at all and only learn they have the condition when they cannot get pregnant or after surgery for another reason. [5]

Endometriosis can also mimic other conditions, including pelvic inflammatory disease, ovarian cysts, and irritable bowel syndrome (IBS). IBS can occur alongside endometriosis, which makes pinning down the exact cause of symptoms harder.

When to see a doctor

Contact a healthcare provider if you suspect endometriosis symptoms. Acting sooner rather than later makes the condition easier to manage, and you can take better charge of symptoms by learning about the condition and working with a team of health care professionals when needed. Pelvic pain that goes beyond tolerable cramping, pain that makes you miss school, work, or normal activities, deserves evaluation.

What causes endometriosis?

The exact cause is not known. [5] Some researchers believe endometriosis may actually begin during fetal development. Six possible explanations have been proposed.

Possible cause	How it might work
Retrograde menstruation	Menstrual blood flows backward through the fallopian tubes into the pelvic cavity; endometrial cells stick to pelvic walls and organs, then grow, thicken, and bleed each cycle [1]
Transformed peritoneal cells	Hormones or immune factors may transform cells lining the abdomen (peritoneal cells) into uterus-like cells [1]
Embryonic cell changes	Estrogen may transform embryonic cells into endometrial-like growths, possibly beginning during development before birth
Surgical scar complication	Endometrial cells may attach to surgical scar tissue, for example after a C-section [1]
Endometrial cell transport	Blood vessels or tissue fluid may carry endometrial cells to other parts of the body [1]
Immune system condition	The immune system may fail to recognize and destroy endometriosis tissue [5]

Risk factors

Risk factor	Why it matters
Never giving birth	Increases the likelihood of developing endometriosis [1] [3]
Early period onset	Starting menstruation at an early age raises risk [1]
Menopause at an older age	Longer lifetime exposure to hormones [1]
Short menstrual cycles	Cycles shorter than 27 days [1] [5]
Heavy, prolonged periods	Menstrual bleeding lasting longer than seven days [3]
Higher estrogen levels	Greater lifetime exposure to estrogen produced by the body
Low body mass index	Lower BMI is associated with higher risk
Family history	A mother, aunt, or sister with endometriosis [3]
Blocked menstrual outflow	Any condition that prevents blood from leaving the body during periods [1] [3]

Endometriosis symptoms often begin years after menstruation starts. Symptoms may improve for a time with pregnancy and can become milder after menopause, unless estrogen therapy is used. [1] [5]

Complications

The main complication is infertility. Up to half of people with endometriosis have difficulty conceiving. The condition can block a fallopian tube and keep the egg and sperm from uniting, and it may also damage the sperm or egg in less direct ways. [1] [5] Even so, many people with mild to moderate endometriosis can still conceive and carry a pregnancy to term, and providers sometimes advise against delaying having children because the condition can worsen with time.

The second complication is cancer. Some studies suggest endometriosis raises the risk of ovarian cancer, but the overall lifetime risk stays low to begin with and remains fairly low. Rarely, a cancer called endometriosis-associated adenocarcinoma can occur later in life.

How doctors diagnose endometriosis

Endometriosis can be elusive. Most of the time it cannot be seen on imaging because the vast majority of it is superficial, described by experts as being almost like paint spackling on a wall. The exception is deep-infiltrating endometriosis, which grows into organs such as the bowel or bladder and can often be seen on ultrasound or MRI.

Test	How it works
Pelvic exam	A provider checks the pelvis with gloved fingers for cysts, painful spots, nodules, and scars behind the uterus; small areas usually cannot be felt unless a cyst has formed [2] [3]
Ultrasound	Sound waves create images of the pelvic organs; a transvaginal version uses a wandlike transducer; it cannot confirm endometriosis but can find cysts called endometriomas [2]
MRI	A magnetic field and radio waves make detailed images; often used to plan surgery by showing the location and size of growths [2]
Laparoscopy	The only definitive test: under general anesthesia, a camera is inserted through a small cut near the navel; tissue that looks like endometriosis is removed and examined under a microscope [2] [5]

With proper planning, a surgeon can often treat endometriosis during the same laparoscopy, so only one surgery is needed. [2]

Treatment options

Treatment depends on how severe the symptoms are and whether pregnancy is a goal. [2] Medicine is typically tried first, and surgery becomes an option if it does not help enough. [2]

The usual path from exam and imaging to confirmation, medicine, and surgery.

Approach	What is involved	What to know
Pain medicines	Over-the-counter NSAIDs such as ibuprofen (Advil, Motrin IB) or naproxen sodium (Aleve)	Help ease painful menstrual cramps [2]
Hormonal contraceptives	Birth control pills, shots, patches, and vaginal rings	Control the hormones that stimulate endometriosis; many people have lighter, shorter flow; relief improves with a year or more of uninterrupted pill use [2]
Gn-RH agonists and antagonists	Medicines that block the menstrual cycle and lower estrogen, creating an artificial menopause	Shrink endometriosis tissue; a low dose of estrogen or progestin can ease side effects such as hot flashes, vaginal dryness, and bone loss; periods and fertility return after stopping [2]
Progestin therapy	An IUD releasing levonorgestrel (Mirena, Skyla), an arm implant (Nexplanon), birth control shots (Depo-Provera), or a progestin-only pill (Camila, Slynd)	Can stop menstrual periods and the growth of endometriosis tissue [2]
Aromatase inhibitors	Medicines that lower the body's estrogen amount	Usually combined with a progestin or combination birth control pills [2]
Conservative surgery	Laparoscopic removal of endometriosis tissue while preserving the uterus and ovaries	May boost pregnancy chances and help severe pain, but tissue and pain can return over time; hormone medicine is sometimes given after surgery [2]
Fertility treatment	Medicines that help the ovaries produce more eggs; in vitro fertilization (IVF) [2] [4]	For those with difficulty conceiving; a reproductive endocrinologist guides the plan [2]
Hysterectomy with ovary removal	Surgery to remove the uterus, sometimes with the ovaries (oophorectomy)	Once considered the most effective treatment, now viewed as a last resort when other treatments fail; removal of the ovaries causes early menopause and carries risks to heart and metabolic health; removing all endometriosis tissue carefully may be preferred instead [2]

An important note from specialists: endometriosis is not a problem of the uterus itself, so removing the uterus does not directly treat it. A related condition called adenomyosis, which occurs concurrently in 80 to 90 percent of patients, can make the uterus a source of pain, and hysterectomy is sometimes considered for that reason.

Finding a health care professional you feel comfortable with is key to managing the condition. A second opinion before starting any treatment is a reasonable step to understand all options, their pros and cons. [2]

Lifestyle and home remedies

Until a treatment that works is found, some home measures can help ease pain. Warm baths and a heating pad relax the pelvic muscles, which lessens cramping and pain. [2] NSAIDs can also be used at home to ease menstrual cramps. [2]

Physical therapy may help too. A pelvic floor therapist can teach relaxation of the muscles that support the uterus, and loosening these tight muscles may make endometriosis-related pelvic pain feel less intense. [2]

Some people report pain relief from alternative therapies such as acupuncture, chiropractic care, herbs (cinnamon twig or licorice root), and supplements (vitamin B1, magnesium, omega-3 fatty acids). [2] [3] Acupuncture has shown some promise, but overall there is little research on how much relief these approaches provide. [2] Always check with your health care team before starting an alternative therapy, because supplements and herbs can interact with standard medicines. [2]

A support group, in person or online, can also help. Talking with people who can relate to the pain, the fertility struggles, and the emotional toll sometimes makes a real difference. [2]

Preparing for the appointment

The first appointment is usually with a primary care doctor or a gynecologist. If you are seeking infertility treatment, you may be referred to a reproductive endocrinologist. [2]

Before the visit, prepare a description of your symptoms, a list of all medicines, vitamins, and supplements with doses, and a prioritized list of questions. Useful questions include what is causing the symptoms, what tests are needed, what treatment options exist, what side effects to expect, what options exist if pregnancy is a goal, and whether alternative treatments are worth trying. [2]

Your doctor will likely ask about the nature of your symptoms, when they occur in relation to your menstrual cycle, and whether you have a family history of endometriosis. [2] [5]

Conclusion and next steps

Endometriosis is a real, progressive condition, and pelvic pain that goes beyond normal cramping is never something to simply endure. The tissue grows outside the uterus, behaves like the uterine lining with every cycle, and can form cysts, scar tissue, and adhesions in the pelvis. The good news is that treatment works for most people, starting with pain medicines and hormone therapy and moving to surgical removal when needed. If your periods are hurting too much, if you are missing activities, experiencing pain with sex or bowel movements, or struggling to conceive, the next step is an appointment with a primary care provider or gynecologist.

Take action: If severe period pain, pain with sex, or fertility concerns are on your mind, contact a healthcare provider. Pain beyond normal cramping is not normal and does not need to be endured.

Frequently asked questions

Can endometriosis be seen on an ultrasound or MRI?

Most of the time, no. The vast majority of endometriosis is superficial and cannot be seen on imaging. The exception is deep-infiltrating endometriosis, which grows into the bowel or bladder and can often be seen on ultrasound or MRI. Surgery with microscopic tissue examination is the only way to confirm the diagnosis. [3]

Is endometriosis a sign that something is wrong with my uterus?

No. Endometriosis involves tissue growing outside the uterus, so the uterus itself is not the problem. A related condition called adenomyosis, which occurs alongside endometriosis in 80 to 90 percent of patients, does involve the uterus and is sometimes treated with hysterectomy.

Can I get pregnant if I have endometriosis?

Yes. The vast majority of people with endometriosis are able to achieve pregnancy. Although up to half of people with the condition have difficulty conceiving, those with mild to moderate endometriosis can often still conceive and carry a pregnancy to term.

What happens if endometriosis is left untreated?

Endometriosis is a progressive condition, so it can continue to grow and cause worsening symptoms. Pain that starts only with the menstrual cycle can eventually spread to other times of the month and to urination, bowel movements, and intercourse. That said, treatment is driven by quality of life; if symptoms are mild and not disruptive, intervention may not be needed.

Does the amount of endometriosis tissue determine how much pain I feel?

No. Pain severity does not match the amount or extent of tissue. Someone with a small amount of endometriosis can have severe pain, while someone with a lot of tissue can have little or no pain. [1] [5] Some people have no symptoms at all. [5]

This article is for general education and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about your individual situation.

Trusted external resources

• Endometriosis fact sheet, Office on Women's Health, U.S. Department of Health and Human Services

• About assisted reproductive technology (ART), Centers for Disease Control and Prevention

Related Reading

Hysterectomy (Surgical Removal of the Uterus)

Robotic-Assisted Hysterectomy: A Patient’s Guide to Minimally Invasive Care

Laparoscopy: What It Is, Uses, Procedure and Recovery explains how a laparoscopy is done, why it is used to confirm and treat endometriosis and what recovery involves.

Pelvic Ultrasound: Types, Preparation, What It Shows and Results explains the imaging test often used to find or rule out this condition.

Learn more in our guide to Transvaginal Ultrasound: Why It's Done, How to Prepare and What to Expect.

Hysterosalpingogram (HSG): Timing, What to Expect and What It Finds explains how an HSG checks the fallopian tubes and uterus.

Anti-Müllerian Hormone (AMH) Test: Normal Levels by Age and What Results Mean explains how AMH estimates ovarian reserve and what results mean.

CA-125 Blood Test: What It Measures, Normal Levels and What High Results Mean explains the blood test used to monitor ovarian cancer, normal CA-125 levels and why a high result isn't a diagnosis on its own.

Endometriosis Ultrasound: What It Can Find, What It Misses, Preparation and Results explains the specialized transvaginal scan that maps endometriomas and deep nodules.

References

1. Liu JH. Endometriosis. Merck Manual Professional Edition. Full Review August 2026; Last updated August 2026. https://www.merckmanuals.com/professional/gynecology-and-obstetrics/endometriosis/endometriosis

2. Mayo Clinic Staff. Endometriosis: Diagnosis and treatment. Mayo Clinic. August 30, 2024. https://www.mayoclinic.org/diseases-conditions/endometriosis/diagnosis-treatment/drc-20354661

3. Office on Women's Health, U.S. Department of Health and Human Services. Endometriosis. womenshealth.gov. Content last reviewed August 18, 2014. https://womenshealth.gov/sites/default/files/documents/fact-sheet-endometriosis.pdf

4. Centers for Disease Control and Prevention. About ART. CDC. December 10, 2024. https://www.cdc.gov/art/about/index.html

5. Cleveland Clinic. Endometriosis. Cleveland Clinic. Last updated September 16, 2024. https://my.clevelandclinic.org/health/diseases/10857-endometriosis

6. Grammatis AL, Gibbons T, Anucha EN, Becker CM. Progesterone receptor modulators for endometriosis. Cochrane Database Syst Rev. 2026;9(9):CD009881. PMID 42746927. https://doi.org/10.1002/14651858.CD009881.pub3

7. Kalaitzopoulos DR, Zografou M, Daniilidis A, et al. The impact of unilateral endometriomas on ovarian response to stimulation: a systematic review and meta-analysis. Hum Reprod. 2026;41(10):1715-1724. PMID 42672534. https://doi.org/10.1093/humrep/deag137

Medical disclaimer

Medical content last reviewed October 2026. This article is for educational purposes only and is not medical advice.