Sexual Health Reproductive Health Issues Uterine Conditions Endometriosis What Are the Stages of Endometriosis? By Lana Barhum Lana Barhum Facebook LinkedIn Lana Barhum has been a freelance medical writer for over 10 years. She shares advice on living well with chronic disease. Learn about our editorial process Updated on December 07, 2020 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Anita Sadaty, MD Medically reviewed by Anita Sadaty, MD Facebook LinkedIn Twitter Anita Sadaty, MD, is a board-certified obstetrician-gynecologist at North Shore University Hospital and founder of Redefining Health Medical. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Determining Stages of Endometriosis Stage I Stage II Stage III Stage IV Making Sense of Staging Endometriosis is a painful condition where tissue that is similar (but not identical) to the kind inside the uterus (endometrium) grows outside of it. These abnormal tissue growths (endometrial implants or lesions) can be located throughout the body, but tend to be found on or near the reproductive organs. The most common sites are the ovaries, the fallopian tubes, and the cul de sac behind the uterus. Implants may also be found in the nearby urinary tract and bowel. Endometriosis is classified into one of four stages. The stage is determined based on the number of endometrial implants, how deep the implants are, and whether cysts or scarring are present. It's important to note the stage does not necessarily reflect the level of pain or specific symptoms a person with endometriosis experiences. 9 Signs of Endometriosis You Shouldn't Ignore Determining Stages of Endometriosis The most common method is a points rating and numerical scale system created by the American Society of Reproductive Medicine (ASRM), which determines disease stages by assigning points according to characteristics of the disease. ASRM's scale has four stages: Stage I: Minimal disease (five points or less) Stage II: Mild disease (six to 15 points) Stages III and IV: Moderate to severe disease (16 points and higher) In addition to the current scale, researchers are also working on new methods to evaluate and stage endometriosis. Diagnosing Endometriosis Verywell / Cindy Chung While exact numbers are not known, global statistics have shown that one in 10 women of reproductive age have endometriosis. The condition is primarily diagnosed in people who identify as female, but it is not exclusive to them. Transgender men and people who are gender non-conforming can also have endometriosis. While rare, lesions have been found in cisgender men receiving estrogen therapy to treat prostate cancer or after surgery to repair inguinal hernias. Diagnosing endometriosis can be challenging, in part because many common symptoms, such as pelvic and abdominal pain, can be caused by other health conditions. However, around 70% of women with chronic pelvic pain are found to have endometriosis. It takes an average of 10 years after the onset of symptoms for an official diagnosis of endometriosis to be made. There are also other reasons diagnosing endometriosis is challenging: For example, unless endometriosis is advanced and has caused other issues with organs and structures (such as ovarian cysts) it typically doesn't show up on diagnostic imaging tests such as a CT scan or ultrasound. If a doctor suspects endometriosis, the only way to confirm the diagnosis is to do a surgery to look inside the pelvis and abdomen (visual confirmation) and take a sample of tissue (biopsy) to look at under a microscope. During a diagnostic laparoscopy (a surgical procedure using a fiber-optic instrument inserted in the abdominal wall) ta surgeon makes a small incision in the abdomen. They insert a thin tube with a light and camera through the incision to see inside the pelvic and abdominal cavity. If implanted endometrial tissue, scar tissue, cysts, adhesions, or other indications of endometriosis are seen, a surgeon may be able to make the diagnosis visually and take a tissue sample to confirm. Points are assigned based on the characteristics of the endometrial lesions to determine the stage of the disease. However, it's important to know that surgeons who are not specially-trained may not recognize endometriosis lesions, or that the lesions may not be visible to the naked eye at all. Depending on the stage of the disease, lesions can vary in appearance, color, and depth. Even using surgical lighting and scopes, surgeons may not be able to see lesions that are superficial and clear, for example. How Is Endometriosis Diagnosed? Stage I Stage I or "minimal" endometriosis scores one to five points. At this stage, endometrial implants are few in number, small, and superficial. The implants may be found on organs or the tissue that lines the pelvis and abdominal cavity. Scar tissue is not present or is minimal. Disease stage doesn’t necessarily correspond to pain levels and other symptoms. Having Stage I endometriosis doesn't mean a person will have few or no symptoms, or that the disease won't have a major impact on their life. Stage II Stage II or "mild disease" scores between six and 15 points. At this stage, there are more implants, and they are deeper than in Stage I. There can be scar tissue at this stage, but not be signs of active inflammation. Stage III Stage III or "moderate disease" has between 16 and 40 points. At this stage, there are many deep endometrial implants and endometrial cysts in at least one of the ovaries. These cysts, called ovarian endometriomas, form when endometrial tissue attaches to an ovary. As the tissue sheds, it collects along with old, thick, brown blood. Based on the appearance of the blood, ovarian endometriomas are sometimes called "chocolate cysts." An Overview of Ovarian Cysts At this stage, filmy adhesions may be present. These thin bands of scar tissue form in response to the body's attempts to protect itself from the inflammation caused by endometriosis. Adhesions tend to make organs to stick together, which can cause sharp, stabbing pain, as well as other symptoms depending on their location. For example, when on the reproductive organs, adhesions contribute to subfertility and can make it harder for someone to get pregnant. Adhesions on the bowel may lead to gastrointestinal symptoms, such as nausea. People with endometriosis can develop adhesions from the disease as well as the surgeries used to diagnose and treat it. Stage IV Stage IV is the most severe stage of endometriosis, typically accruing over 40 points. At this stage, a large number of cysts and severe adhesions are present. While some types of cysts go away on their own, the cysts that form as a result of endometriosis usually need to be surgically removed. Endometriomas can grow to be quite large; even as big as a grapefruit. Small cysts on the back wall of the uterus and rectum may also be found at this stage. People with endometriosis in these areas may experience painful bowel movements, abdominal pain, constipation, nausea, and vomiting. If endometrial lesions, cysts, or scar tissue is blocking one or both fallopian tubes, a person with endometriosis may experience infertility. Sometimes, trouble conceiving is the only symptom of endometriosis a person has. Treating severe endometriosis is difficult. Even if a surgeon makes the diagnosis, they may not be familiar with or have experience using the surgical techniques for removing the lesions. While there are non-surgical ways to treat endometriosis (including hormonal birth control and other medications) the "gold standard" treatment is a highly-specialized procedure called excision surgery. To manage endometriosis, someone might need to use more than one form of treatment. Sometimes, multiple surgeries are needed to treat the disease and control pain. If you are diagnosed with endometriosis, it can be helpful to get a referral to an endometriosis specialist to discuss your treatment options. Verywell / Alex Dos Diaz Learn the Different Ways Endometriosis Is Treated Making Sense of Staging People often think the stages of endometriosis are determined similarly to cancer stages, but endometriosis doesn’t spread or grow the same way cancer cells do. Cancer starts in one part of the body and spreads to distant organs. As cancer progresses, a person usually feels sicker, may have more pain, and has more complications related to the disease. On the other hand, endometriosis can be widespread even in the early stages, and the disease stage doesn't necessarily correlate with someone's symptoms, pain levels, or complications like digestive problems and fertility issues. The stage of endometriosis also doesn't reflect how severe a person's symptoms are, how much pain they are in, or the degree to which their quality of life has been affected. Coping With Endometriosis Unlike other diseases that can be staged, endometriosis won't necessarily progress through the stages in a predictable way. Research has shown that without treatment (particularly if diagnosed during adolescence) endometriosis might improve, get worse, or stay the same. There is currently no method to predict which outcome a person with the disease will have. Researchers also aren't sure why some people have severe disease and others do not, or why the stages of endometriosis don't always correspond to the severity of symptoms, pain, and complications a person with the disease experiences. Further complicating its management, these stages don't offer much guidance for treating endometriosis to medical professionals. Endometriosis needs to be evaluated on a case-by-case basis, and each patient will need an individualized approach to treating the disease and managing symptoms. A Word From Verywell There is no cure for endometriosis and it can be challenging to diagnose. Once the disease is accurately diagnosed and staged, people with endometriosis can discuss the most effective strategies for managing and treating their symptoms. People may need to use more than one kind of treatment to control pain and resolve other symptoms related to endometriosis. Specialized surgery is recommended for severe endometriosis. In some cases, people may need more than one surgery to treat the disease and the complications it can cause. People with endometriosis who have pain, digestive problems, infertility, and other symptoms can also try non-surgical treatment strategies, including medications and hormone therapy. Teen Acne: Talking to Your Parents About Seeing a Dermatologist Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 25 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Kennedy S, Bergqvist A, Chapron C, et al. ESHRE guideline for the diagnosis and treatment of endometriosis. 2005;20(10):2698-2704. doi:10.1093/humrep/dei135 Endometriosis.org. About Endometriosis. The American Society of Reproductive Medicine. Revised American Society for Reproductive Medicine classification of endometriosis: 1996 (PDF). Fertil Steril. 1997;67(5):817-21. Alimi Y, Iwanga J, Loukas, et al. The Clinical Anatomy of Endometriosis: A Review. Cureus. 2018 Sep; 10(9): e3361. doi: 10.7759/cureus.3361 Johnson NP, Hummelshoj L, Adamson GD, et al. World Endometriosis Society consensus on the classification of endometriosis. Hum Reprod. 2017;32(2):315-324. doi:10.1093/humrep/dew293 Parasar P, Ozcan P, Terry KL. Endometriosis: Epidemiology, Diagnosis and Clinical Management. Curr Obstet Gynecol Rep. 2017;6(1):34-41. doi:10.1007/s13669-017-0187-1 Jabr F, Mani V. An unusual cause of abdominal pain in a male patient: Endometriosis. Avicenna J Med. 2014;4(4):99. doi:10.4103/2231-0770.140660 Parasar P, Ozcan P, Terry, KL. Endometriosis: Epidemiology, Diagnosis and Clinical Management. Curr Obstet Gynecol Rep. 2017 Mar; 6(1): 34–41. doi:10.1007/s13669-017-0187-1 Agarwal SK, Chapron C, Giudice LC, et al. Clinical diagnosis of endometriosis: a call to action. Am J Obstet Gynecol. 2019 Apr;220(4):354.e1-354.e12. doi:10.1016/j.ajog.2018.12.039 Nisenblat V, Bossuyt PM, Farquhar C, Johnson N, Hull ML. Imaging modalities for the non-invasive diagnosis of endometriosis. doi:10.1002/14651858.CD009591.pub2 Hopton EN, Redwine DB. Eyes wide shut: the illusory tale of ‘occult’ microscopic endometriosis. Human Reproduction. 2014;29(3):384-387. doi:10.1093/humrep/det441 Rolla E. Endometriosis: advances and controversies in classification, pathogenesis, diagnosis, and treatment. F1000Res. 2019;8 doi:10.12688/f1000research.14817.1 Subramanian A, Agarwal N. Endometriosis - Morphology, clinical presentations and molecular pathology. J Lab Physicians. 2010;2(1):1. doi:10.4103/0974-2727.66699 Grandi G, Toss, A, Coresti L, et al. The Association between Endometriomas and Ovarian Cancer: Preventive Effect of Inhibiting Ovulation and Menstruation during Reproductive Life. Biomed Res Int. 2015; 2015: 751571. doi:10.1155/2015/751571 Vercellini P, Viganò P, Somigliana E, et al. Endometriosis: pathogenesis and treatment. Nat Rev Endocrinol. 2014 May;10(5):261-75. doi:10.1038/nrendo.2013.255 De wilde RL, Alvarez J, Brölmann H, et al. Adhesions and endometriosis: challenges in subfertility management : (An expert opinion of the ANGEL-The ANti-Adhesions in Gynaecology Expert PaneL-group). Arch Gynecol Obstet. 2016;294(2):299-301. doi:10.1007/s00404-016-4049-2 Wallwiener M, Brölmann H, Koninckx PR, et al. Adhesions after abdominal, pelvic and intra-uterine surgery and their prevention. Gynecol Surg. 2012;9(4):465-466. doi:10.1007/s10397-012-0762-4 Zondervan KT, Becker CM, Koga K, Missmer SA, Taylor RN, Viganò P. Endometriosis. Nat Rev Dis Primers. 2018;4(1):9. doi:10.1038/s41572-018-0008-5 Ozkan S, Murk W, Arici A. Endometriosis and Infertility. 2008;1127(1):92-100. doi:10.1196/annals.1434.007 Nisenblat V, Prentice L, Bossuyt PM, Farquhar C, Hull ML, Johnson N. Combination of the non-invasive tests for the diagnosis of endometriosis. Cochrane Database Syst Rev. 2016;7:CD012281 doi:10.1002/14651858.CD012281 U.S. Department of Health and Human Services National Institutes of Health National Cancer Institute. Cancer Staging. National Cancer Institute. Rolla E. Endometriosis: advances and controversies in classification, pathogenesis, diagnosis, and treatment. F1000Res. 2019;8 doi:10.12688/f1000research.14817.1 Brosens I, Gordts S, Benagiano G. Endometriosis in adolescents is a hidden, progressive and severe disease that deserves attention, not just compassion. Human Reproduction. 2013;28(8):2026-2031. doi:10.1093/humrep/det243 Koninckx PR, Ussia A, Keckstein J, et al. Evidence-Based Medicine: Pandora's Box of Medical and Surgical Treatment of Endometriosis. J Minim Invasive Gynecol. 2018;25(3):360-365. doi:10.1016/j.jmig.2017.11.012 Saraswat L, Ayansina D, Cooper KG, Bhattacharya S, Horne AW, Bhattacharya S. Impact of endometriosis on risk of further gynaecological surgery and cancer: a national cohort study. BJOG. 2018;125(1):64-72. doi:10.1111/1471-0528.14793 Additional Reading Agarwal SK, Chapron C, Giudice LC, et al. Clinical diagnosis of endometriosis: a call to action. Am J Obstet Gynecol. 2019 Apr;220(4):354.e1-354.e12. doi:10.1016/j.ajog.2018.12.039 Endometriosis Foundation of America (EndoFound). Endometriosis Stages: Understanding The Different Stages Of Endometriosis. Endometriosis : Causes - Symptoms - Diagnosis - And Treatment. Endometriosis Research Center. Do You Have Endo? ERC. Grandi G, Toss, A, Coresti L, et al. The Association between Endometriomas and Ovarian Cancer: Preventive Effect of Inhibiting Ovulation and Menstruation during Reproductive Life. Biomed Res Int. 2015; 2015: 751571. doi:10.1155/2015/751571 Parasar P, Ozcan P, Terry, KL. Endometriosis: Epidemiology, Diagnosis and Clinical Management. Curr Obstet Gynecol Rep. 2017 Mar; 6(1): 34–41. doi:10.1007/s13669-017-0187-1