Enlarged Ovary Endometriosis and Fibroids: What to Know

An enlarged ovary is a symptom, not a diagnosis. It can be caused by several conditions—most commonly functional cysts, endometriosis (especially ovarian endometriomas), or less commonly tumors and ovarian torsion. Uterine fibroids, by contrast, arise from the muscle of the uterus and do not enlarge the ovary itself. Because pelvic symptoms from endometriosis and fibroids often overlap, it’s important to understand how they differ, how they’re diagnosed, and which treatments are available.

Can endometriosis or fibroids enlarge an ovary?

• Endometriosis: Yes. Endometriosis can form cysts in the ovary called endometriomas (“chocolate cysts”), which can enlarge one or both ovaries.
• Fibroids: No. Fibroids (uterine leiomyomas) grow in or on the uterus—not the ovary. Large, subserosal or pedunculated fibroids can mimic an adnexal mass on exam or imaging, but they do not arise from or enlarge the ovary.

Other causes of an enlarged ovary include benign functional cysts, polycystic ovary syndrome (PCOS), ovarian torsion, and—less commonly—benign or malignant ovarian tumors. Determining the cause guides safe and effective treatment.

How endometriosis enlarges the ovary

Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus. When these implants involve the ovary, they can form endometriomas that fill with old blood. Endometriomas may:

• Vary in size from a few millimeters to several centimeters
• Raise the risk of ovarian torsion (twisting of the ovary), particularly if larger than about 5 cm
• Adhere to nearby organs, contributing to chronic pelvic pain
• Affect fertility by altering ovarian tissue and reducing egg reserve, especially after repeated surgeries

Symptoms to watch for

Both endometriosis and fibroids can cause overlapping symptoms, but some features can help differentiate them.

More suggestive of endometriosis/endometrioma

• Pelvic pain that worsens around menstruation
• Pain with intercourse (dyspareunia)
• Pain with bowel movements or urination during periods
• Infertility or difficulty conceiving
• Ovarian cyst found on imaging

More suggestive of uterine fibroids

• Heavy or prolonged menstrual bleeding (soaking a pad/tampon every 1–2 hours)
• Pelvic pressure, urinary frequency, constipation
• Enlarged, irregularly shaped uterus on exam
• Anemia-related fatigue or shortness of breath

How doctors find the cause

• History and pelvic exam: Can reveal uterine enlargement (fibroids) or focal tenderness (ovary).
• Transvaginal ultrasound (first-line): Identifies uterine fibroids and characterizes ovarian cysts. Endometriomas often show a classic “ground glass” appearance.
• MRI: Helpful when ultrasound is inconclusive, when mapping fibroids pre-surgery, or further characterizing ovarian cysts.
• Blood tests: Pregnancy test if appropriate; blood count if heavy bleeding; CA-125 may be elevated in endometriosis but is not diagnostic.
• Diagnostic laparoscopy: Minimally invasive surgery that can confirm and treat endometriosis. Not required for all patients but remains the definitive way to visually diagnose endometriosis when needed.

Treatment options

Your plan should be personalized to your symptoms, imaging findings, age, fertility goals, and other health factors. Many options are stepwise—starting with medication and moving to procedures if needed.

If the enlarged ovary is due to an endometrioma

• Watchful waiting: Small, asymptomatic cysts with benign features on imaging may be monitored with repeat ultrasound.
• Pain and suppression therapy: NSAIDs for pain; hormonal options to suppress endometriosis activity include combined oral contraceptives, progestins (oral, implant, or levonorgestrel-releasing IUD), and GnRH analogs (agonists or antagonists). FDA-approved options for endometriosis-related pain include elagolix (a GnRH antagonist) and relugolix combination therapy (relugolix/estradiol/norethindrone) in appropriate patients; add-back therapy helps protect bone health.
• Surgery: Laparoscopic cystectomy (removing the cyst wall) can reduce recurrence compared with drainage alone, but may lower ovarian reserve. Discuss fertility goals and egg reserve testing with your specialist before surgery. Ablation or drainage may be considered in select cases.

If you have uterine fibroids (not an ovarian cause)

• Medical therapy: NSAIDs for cramps; tranexamic acid for heavy menstrual bleeding; hormonal contraceptives or levonorgestrel IUD to reduce bleeding; GnRH agonists (e.g., leuprolide) or GnRH antagonist combinations (elagolix/estradiol/norethindrone or relugolix/estradiol/norethindrone) to decrease bleeding and shrink fibroids temporarily.
• Procedures: Uterine artery embolization (cuts off fibroid blood flow), radiofrequency ablation, MRI-guided focused ultrasound, myomectomy (fibroid removal, preserving the uterus), or hysterectomy (definitive treatment if childbearing is complete). Choice depends on symptoms, size/location, and fertility plans.

Important distinction: Treating fibroids won’t shrink an endometrioma, and treating an endometrioma won’t shrink uterine fibroids. Clear diagnosis ensures the right therapy.

Fertility and pregnancy considerations

• Endometriomas: Both the cyst and surgical removal can reduce ovarian reserve. If you want future pregnancy, ask about fertility-sparing strategies, timing of surgery, and whether to consult a reproductive endocrinologist. Assisted reproduction may be considered in some cases.
• Fibroids: Submucosal and some intramural fibroids that distort the uterine cavity can affect implantation and increase miscarriage risk. Myomectomy can improve fertility in selected cases.

When to seek medical care

Call your clinician soon if you have:

• New or worsening pelvic pain, especially cyclic pain
• Heavy menstrual bleeding, anemia symptoms (fatigue, dizziness)
• Difficulty conceiving or recurrent pregnancy loss

Seek urgent care immediately for:

• Sudden, severe pelvic pain with nausea/vomiting (possible torsion)
• Fever with pelvic pain (possible infection)
• Fainting, or soaking more than one pad per hour for over two hours

How to prepare for your appointment

• Track your cycles, pain timing, and bleeding volume.
• Bring prior imaging reports or list where they were done.
• Clarify your goals (pain control, preserving fertility, reducing bleeding).
• Ask about benefits, risks, and impacts on fertility for each option.

Bottom line: Endometriosis can enlarge the ovary via endometriomas; fibroids do not. Accurate diagnosis—usually with ultrasound and sometimes MRI—guides targeted treatment. Safe, effective options exist for both conditions, including medications and minimally invasive procedures. Work with a gynecologist to tailor a plan to your symptoms and life goals.

This article is for educational purposes and does not replace personalized medical advice. Always consult a qualified clinician for diagnosis and treatment.

Sources and further reading

• NIH MedlinePlus: Endometriosis – https://medlineplus.gov/endometriosis.html
• NIH MedlinePlus: Uterine Fibroids – https://medlineplus.gov/uterinefibroids.html
• Office on Women’s Health (U.S. HHS): Endometriosis – https://www.womenshealth.gov/a-z-topics/endometriosis
• ACOG Patient FAQ: Endometriosis – https://www.acog.org/womens-health/faqs/endometriosis
• ACOG Patient FAQ: Uterine Fibroids – https://www.acog.org/womens-health/faqs/uterine-fibroids
• FDA: Oriahnn (elagolix/estradiol/norethindrone) – https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/oriahnn
• FDA: Myfembree (relugolix/estradiol/norethindrone) – https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/myfembree
• FDA: Lupron Depot (leuprolide acetate) – https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/lupron-depot
• FDA: Lysteda (tranexamic acid) – https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/lysteda