Endometriosis Stages Chart and Fibroids: What to Know

Endometriosis Stages Chart and Fibroids: What to Know

Endometriosis and uterine fibroids are two common, often confusing causes of pelvic pain and heavy periods. They can occur separately or together, and while they share some symptoms, they are different conditions that require different approaches. Understanding how endometriosis is staged—and how staging relates (and doesn’t relate) to symptoms—can help you ask the right questions and choose the right treatment plan, especially if fibroids are also part of the picture.

Endometriosis vs. Fibroids: A quick refresher

Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus, commonly on the ovaries, pelvic lining, or fallopian tubes. It’s estrogen-responsive and can cause inflammation, scarring, and adhesions. An estimated 10% of reproductive-age women are affected, and it’s a leading cause of pelvic pain and infertility.

Uterine fibroids (leiomyomas) are noncancerous growths of the muscle wall of the uterus. They are extremely common—many women develop them by age 50—and can cause heavy menstrual bleeding, pelvic pressure, and reproductive issues, depending on their size and location.

While distinct, the two conditions can coexist. Both are influenced by estrogen and can contribute to pain, heavy bleeding, and fertility challenges. A careful evaluation helps distinguish which condition (or both) is driving your symptoms.

The endometriosis stages chart, explained

Clinicians often use the revised American Society for Reproductive Medicine (rASRM) staging system to describe the extent of endometriosis observed during surgery. The system assigns points based on the number, size, and depth of lesions and the presence of adhesions, then groups cases into four stages:

  • Stage I (Minimal): Few small, superficial implants; little to no scarring.
  • Stage II (Mild): More and slightly deeper implants than Stage I; limited scarring.
  • Stage III (Moderate): Numerous implants, some deep; possible small endometriomas (ovarian cysts) and more significant adhesions.
  • Stage IV (Severe): Many deep implants, large endometriomas, and dense adhesions that can distort pelvic anatomy.

Important caveat: the stage is a description of what is seen in the pelvis, primarily at surgery. It does not necessarily predict how much pain you will have or whether you’ll have trouble getting pregnant. People with minimal disease can have severe pain, and some with severe disease may have manageable symptoms. Staging is most useful for surgical planning, research, and communicating disease extent among clinicians.

Some specialists also use complementary systems, such as the Enzian classification for deep infiltrating endometriosis, to better map disease behind the uterus, on the bowel, or in the bladder. Your surgeon may reference one or more systems to guide care.

Symptoms overlap—and key differences

Because endometriosis and fibroids can share symptoms, it’s helpful to note patterns that point more strongly to one or the other:

  • Pain: Endometriosis is strongly associated with cyclical pelvic pain, pain with periods (dysmenorrhea), pain with sex (dyspareunia), and sometimes pain with bowel movements or urination, especially during menstruation. Fibroids can cause pelvic pressure or pain, particularly when larger or degenerating, but are often less tied to cycle timing.
  • Bleeding: Heavy or prolonged periods (menorrhagia) are classic for fibroids, especially when fibroids distort the uterine cavity. Endometriosis can involve irregular bleeding but heavy bleeding is less characteristic.
  • Fertility: Both can impact fertility. Endometriosis may alter egg quality, tubal function, and pelvic anatomy; fibroids—particularly those within the uterine cavity—can interfere with implantation or pregnancy maintenance.

How each is diagnosed

Endometriosis: A thorough history and pelvic exam are first steps. Imaging like ultrasound or MRI can identify endometriomas and suggest deep disease, but superficial implants are often invisible on imaging. Historically, laparoscopy with biopsy has been the gold standard for diagnosis; however, many clinicians make a presumptive clinical diagnosis and begin treatment to avoid delays.

Fibroids: Pelvic ultrasound is the mainstay. MRI can help map fibroid size and location before procedures. The number, size, and location (submucosal, intramural, subserosal) guide management decisions, especially for fertility goals.

Treatment options: what evidence-based care looks like

Managing endometriosis

  • Pain relief: NSAIDs can help with menstrual pain.
  • Hormonal suppression: Combined hormonal contraceptives, progestin-only pills, depot medroxyprogesterone, or levonorgestrel-releasing IUDs can lighten periods and reduce pain.
  • GnRH modulation: Medications that lower estrogen signaling can reduce endometriosis pain. Examples include GnRH antagonists such as elagolix (FDA-approved for moderate to severe endometriosis pain) and combination therapies like relugolix/estradiol/norethindrone (approved for endometriosis-associated pain). These are typically time-limited and may be paired with add-back hormones to mitigate side effects like bone loss.
  • Surgery: Laparoscopic excision or ablation of lesions and lysis of adhesions can relieve pain and improve fertility in selected patients, particularly when imaging suggests endometriomas or deep disease.

Managing fibroids

  • Watchful waiting: If fibroids are small and symptoms are mild.
  • Medical therapy: Options to control bleeding include NSAIDs, tranexamic acid, hormonal contraceptives, levonorgestrel IUDs, and GnRH antagonists in fixed-dose combinations (e.g., elagolix/estradiol/norethindrone or relugolix/estradiol/norethindrone) that are FDA-approved to reduce heavy menstrual bleeding due to fibroids.
  • Procedures: Uterine artery embolization (UAE) shrinks fibroids by cutting off blood supply; myomectomy removes fibroids while preserving the uterus; hysterectomy is definitive. The best choice depends on symptoms, fibroid characteristics, and pregnancy plans. Discuss risks, including the FDA’s guidance around tissue morcellation during surgery.

When endometriosis and fibroids coexist

It’s not uncommon for both conditions to be present, and symptoms can layer on one another—for example, endometriosis-related pelvic pain plus fibroid-related heavy bleeding. In these cases:

  • Clarify your top goals (pain relief, bleeding control, fertility now or later).
  • Expect a stepwise plan that may combine therapies—e.g., medical suppression for endometriosis pain and a fibroid-directed procedure to control bleeding.
  • Consider consultation with a minimally invasive gynecologic surgeon and, if fertility is a priority, a reproductive endocrinologist.

Does endometriosis stage predict your plan?

Not by itself. The rASRM stage summarizes surgical findings, but your care plan is tailored to your symptoms, response to prior treatments, imaging results, age, and goals. Someone with Stage I disease can still need aggressive pain management, and someone with Stage IV disease may opt first for medical therapy if symptoms are controlled. For fertility, stage and lesion location matter, but factors like age and ovarian reserve also guide decisions.

When to seek care

  • Period pain that disrupts school, work, or daily life.
  • Heavy bleeding (soaking a pad or tampon every 1–2 hours, passing large clots, or anemia symptoms).
  • Pain with sex, bowel movements, or urination—especially cyclical.
  • Difficulty conceiving after 6–12 months (earlier if over 35 or if symptoms are severe).
  • Sudden, severe pelvic pain.

This article is educational and not a substitute for medical advice. Bring your symptoms and questions to a clinician who can personalize recommendations.

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