Endomitriomas and Fibroids: What to Know

September 13, 2025

Endometriomas and Fibroids: What to Know

Pelvic pain, heavy periods, and fertility questions often lead to two common yet distinct diagnoses: endometriomas and uterine fibroids. Both conditions are benign and influenced by hormones, especially estrogen, but they arise from different tissues and require tailored evaluation and treatment. Understanding the overlap—and the differences—helps you advocate for the right care.

Quick definitions

Endometrioma: A type of ovarian cyst caused by endometriosis, in which tissue similar to the uterine lining grows outside the uterus. Endometriomas are sometimes called “chocolate cysts” because they contain old blood.
Uterine fibroid (leiomyoma): A noncancerous growth of muscle and fibrous tissue inside the uterus. Fibroids can be inside the uterine cavity (submucosal), within the muscle wall (intramural), or on the outer surface (subserosal).

Who gets them and why?

Both conditions are common in reproductive-age individuals and are hormonally responsive.

Endometriosis/endometriomas: Risk factors can include early first period, heavy or painful periods, family history, and possibly shorter cycle length. Symptoms often begin in adolescence or the 20s. MedlinePlus (NIH).
Fibroids: Up to 70–80% of people with a uterus develop fibroids by age 50, with earlier onset and more severe symptoms commonly reported among Black women. Family history, age (30s–40s), and higher lifetime estrogen exposure are risk factors. Office on Women’s Health (HHS); NICHD/NIH.

Symptoms: How they overlap and differ

Some patients have both conditions. When symptoms overlap, imaging and a careful exam are key to distinguishing them.

Shared symptoms: Pelvic pain, painful periods, painful sex, bloating, and fertility challenges.
More suggestive of endometrioma: Deep pelvic pain with periods, pain during sex, pain with bowel movements, or chronic pelvic pain that’s cyclical. Some have no symptoms.
More suggestive of fibroids: Heavy or prolonged periods (soaking pads/tampons hourly, clots), anemia, pelvic pressure, urinary frequency/urgency, constipation, and visible abdominal enlargement with larger fibroids.

Diagnosis: What to expect

Pelvic exam: May suggest enlarged, irregular uterus (fibroids) or tender adnexal mass (possible endometrioma).
Ultrasound (first-line): Transvaginal ultrasound typically identifies fibroids and may show features that suggest an endometrioma. MedlinePlus—Ovarian Cysts.
MRI: Helpful for surgical planning, mapping fibroid number/location, or clarifying complex ovarian masses.
Diagnostic laparoscopy: The gold standard for diagnosing endometriosis; can treat endometriosis and endometriomas during the same procedure. ACOG—Endometriosis FAQ.

There is no routine blood test that definitively diagnoses either condition. CA-125 may be elevated with endometriosis but is nonspecific.

Fertility and pregnancy considerations

Endometriomas: These cysts reflect underlying endometriosis, which can impair fertility by causing inflammation, scarring, and reduced ovarian reserve. Surgical removal of an endometrioma can improve pain and sometimes fertility, but may also reduce ovarian reserve; careful surgical technique and individualized planning are essential. ACOG.
Fibroids: Impact on fertility depends on location and size. Submucosal and certain intramural fibroids that distort the uterine cavity are most strongly linked to infertility and miscarriage risk. Treating cavity-distorting fibroids (often via myomectomy) can improve outcomes. ACOG—Uterine Fibroids FAQ.

During pregnancy, fibroids may grow and cause pain or complications (e.g., malpresentation or preterm labor in some cases). Endometriomas sometimes remain stable; rarely, a cyst can rupture or twist (torsion). Preconception counseling with a gynecologist or reproductive endocrinologist is advisable if you have symptoms or known lesions.

Treatment options

There is no one-size-fits-all plan. Management depends on symptoms, size/location, age, fertility goals, and overall health. Many options are stepwise—starting conservative and moving to procedures if symptoms persist.

When watchful waiting is reasonable

Small, minimally symptomatic fibroids can be monitored with periodic exams/imaging.
Endometriomas that are small and not causing significant pain or fertility issues may be observed with regular follow-up, especially before attempting conception or assisted reproduction.

Medications

These aim to control symptoms; effects on size vary.

Pain control: NSAIDs for pelvic pain and cramps.
Hormonal suppression (endometriosis/endometriomas): Combined oral contraceptives, progestins, or the levonorgestrel IUD can reduce pain and menstrual flow. MedlinePlus.
Heavy menstrual bleeding (fibroids): Levonorgestrel IUD and tranexamic acid (non-hormonal) can reduce bleeding. ACOG.
GnRH agonists/antagonists: Temporarily lower estrogen to reduce pain and bleeding; can shrink fibroids while on therapy. Examples include:
- Elagolix for endometriosis pain (FDA: Orilissa).
- Elagolix with add-back therapy for fibroid-related heavy menstrual bleeding (FDA: Oriahnn).
- Relugolix combination for heavy menstrual bleeding due to fibroids and for endometriosis pain (FDA: Myfembree).
- Leuprolide acetate (GnRH agonist) may be used short-term for fibroids or endometriosis, often preoperatively, typically with add-back therapy to protect bone health. See prescribing information via FDA resources.

Note: Hormonal therapies usually suppress endometriosis symptoms but do not eliminate endometriosis or permanently resolve endometriomas. Fibroids often regrow after stopping medical therapy.

Procedural and surgical options

Endometriomas:
- Laparoscopic cystectomy (surgically removing the cyst wall) is the preferred approach for many symptomatic cases; it can relieve pain and reduce recurrence compared with drainage alone. Surgery should be performed by an experienced surgeon to minimize impact on ovarian tissue.
- Ablation/drainage may be considered in select scenarios, but recurrence rates are higher.
Fibroids:
- Myomectomy removes fibroids while preserving the uterus; approaches include hysteroscopic (for submucosal), laparoscopic/robotic, or open surgery depending on size/number.
- Uterine artery embolization (UAE/UFE) shrinks fibroids by blocking their blood supply. Effective for bleeding and bulk symptoms; discuss fertility goals with your clinician, as data on future pregnancy is mixed.
- Radiofrequency ablation and MRI-guided focused ultrasound are minimally invasive options available at select centers.
- Hysterectomy is definitive for those who have completed childbearing or prefer a curative option for fibroid symptoms. ACOG.

Are they cancer?

Endometriomas: Malignant transformation is rare. Concerning changes (rapid growth, new solid components) warrant prompt evaluation.
Fibroids: Fibroids are almost always benign and do not turn into cancer. Uterine leiomyosarcoma is rare and usually arises de novo, not from a preexisting fibroid. NICHD/NIH.

When to seek care

Heavy bleeding that causes anemia (fatigue, dizziness) or impacts daily life
Pelvic pain that’s persistent, severe, or worsening
Fertility concerns or recurrent pregnancy loss
Rapidly enlarging pelvic mass or new symptoms

Smart questions for your appointment

Which condition do you suspect: endometrioma, fibroids, or both?
How will imaging guide diagnosis and treatment?
What are the pros and cons of medical therapy versus procedures for my goals (pain control, fertility, bleeding)?
How might surgery affect ovarian reserve or pregnancy planning?
What follow-up will I need?

This article is for educational purposes and is not a substitute for individualized medical advice. Discuss diagnosis and treatment with your clinician.