Intramural Fibroid Size Chart and Fibroids: What to Know

Intramural fibroids are the most common type of uterine fibroid, growing within the muscular wall of the uterus. Their size can range from a few millimeters to masses large enough to enlarge the uterus and cause significant symptoms. This guide explains how size is measured, offers a practical intramural fibroid size chart, and outlines how size influences symptoms, fertility, and treatment decisions—drawing on guidance from trusted sources such as the National Institutes of Health (NIH), the American College of Obstetricians and Gynecologists (ACOG), and the U.S. Food and Drug Administration (FDA).

Intramural Fibroids 101

Uterine fibroids (leiomyomas) are noncancerous growths arising from the muscle of the uterus. Intramural fibroids originate within the uterine wall and may expand inward toward the cavity or outward toward the outer surface. Many fibroids cause no symptoms, but intramural fibroids can contribute to heavy menstrual bleeding, pelvic pressure, urinary frequency, constipation, pain, and—depending on location and size—reproductive challenges.^{1, 2}

How Size Is Measured

• Imaging: Pelvic ultrasound is the first-line test to detect and measure fibroids. MRI may be used to map fibroids before procedures or when ultrasound is inconclusive.²
• Dimensions: Reports commonly list the largest diameter (in centimeters) and sometimes three dimensions with an estimated volume.
• Uterine size equivalence: Clinicians may describe overall uterine enlargement using “weeks of pregnancy” as a rough size reference (for example, “12-week size uterus”). This is a clinical shorthand rather than a strict standard.

Intramural Fibroid Size Chart (Practical Guide)

There is no universally accepted, formal size chart for fibroids. The ranges below are commonly used in clinical practice to help frame discussions. Size alone does not determine the need for treatment—symptoms, location, growth, and personal goals matter most.

In clinical shorthand, a uterus enlarged by multiple or large fibroids may be described as “10–12 week size” (about at the pubic bone) or larger, but this is an approximation to describe overall uterine volume, not individual fibroid diameters.

How Size Relates to Symptoms and Risks

• Bleeding: Heavy menstrual bleeding does not always correlate with size. A small fibroid that indents the uterine cavity can cause substantial bleeding, while a larger intramural fibroid away from the cavity may cause less bleeding.²
• Pressure and pain: Medium-to-large intramural fibroids (≥3–5 cm) are more likely to cause pelvic pressure, urinary frequency, constipation, or back pain as uterine size increases.^{1, 2}
• Fertility and pregnancy: Intramural fibroids that distort the uterine cavity or significantly enlarge the uterus may lower implantation rates and increase risks such as miscarriage or malpresentation. Many people with fibroids have healthy pregnancies; individualized evaluation is important.^{1, 2}
• Growth and degeneration: Fibroids may grow slowly, remain stable, or shrink (especially after menopause). Rapid growth can cause pain from degeneration but is not by itself a reliable sign of cancer, which is rare.²
• Cancer risk: Uterine sarcomas are uncommon among patients operated on for presumed fibroids. Because preoperative tests cannot reliably exclude sarcoma, the FDA advises caution with techniques that can spread tissue (e.g., power morcellation).³

When to Watch vs. Treat

Treatment is guided by symptoms, reproductive plans, fibroid size and location, rate of growth, and overall health. ACOG and NIH emphasize that many fibroids can be managed expectantly (“watchful waiting”), especially if small and asymptomatic.^{1, 2}

• Observation: Appropriate for small or asymptomatic intramural fibroids. Periodic reassessment is reasonable; imaging intervals depend on symptoms and clinical judgment.
• Consider intervention if:
  • Heavy menstrual bleeding causes anemia or impacts quality of life
  • Bulk symptoms (pressure, urinary frequency, constipation) are significant
  • Infertility or recurrent pregnancy loss may be related to fibroids
  • Rapid increase in uterine size, severe pain, or uncertainty in diagnosis

Treatment Options, by Goals and Typical Size Considerations

Discuss options with a gynecologist who can tailor treatment to your goals (symptom relief, uterine preservation, pregnancy plans) and to fibroid number, size, and location.

• Medications (symptom control; do not remove fibroids):
  • Nonhormonal: NSAIDs for pain; tranexamic acid for heavy bleeding (taken only during menses).²
  • Hormonal: Combined hormonal contraceptives or progestin-only methods (including the levonorgestrel IUD) can reduce bleeding for many patients.²
  • GnRH analogs: Short-term use can shrink fibroids and reduce bleeding. FDA-approved oral GnRH antagonist combinations—elagolix with add‑back therapy (Oriahnn) and relugolix with add‑back (Myfembree)—are options for heavy menstrual bleeding due to fibroids in premenopausal patients.^{4, 5}
• Procedures that preserve the uterus:
  • Myomectomy (surgical removal of fibroids) can be performed via hysteroscopy (for cavity-distorting fibroids), laparoscopy, or open surgery. Larger and multiple intramural fibroids often require laparoscopic or open approaches.²
  • Uterine artery embolization (UAE) blocks blood flow to fibroids, shrinking them and improving bleeding and bulk symptoms; it is uterus-preserving but not typically used when future pregnancy is a top priority.²
  • MRI-guided focused ultrasound is a noninvasive option for select patients and fibroid locations; availability varies.²
• Definitive treatment:
  • Hysterectomy (removal of the uterus) is curative for fibroids and considered when symptoms are severe, childbearing is complete, or other treatments are unsuitable.²

Safety note on tissue removal: The FDA warns that using power morcellators during hysterectomy or myomectomy can spread unsuspected cancer. If morcellation is considered, the FDA recommends use only in carefully selected patients and within a tissue containment system. Discuss risks, benefits, and alternatives with your surgeon.³

Fertility and Pregnancy Considerations

• Intramural fibroids that distort the uterine cavity or are large enough to alter uterine shape may reduce fertility or affect pregnancy outcomes. Preconception evaluation can help identify which fibroids matter most.^{1, 2}
• Myomectomy may improve fertility in select cases; the decision depends on fibroid location, size, and number. Timing of conception after myomectomy and delivery planning should be individualized.²

Key Takeaways

• Intramural fibroid size is typically reported in centimeters and influences symptoms mainly through uterine enlargement and cavity distortion.
• There is no single official size chart, but practical ranges (small, medium, large) help guide discussions. Treatment decisions are driven by symptoms, goals, and imaging—not size alone.
• Effective options range from medications (including FDA‑approved oral therapies for heavy bleeding) to uterus-preserving procedures and hysterectomy.
• Work with a clinician to align treatment with your priorities, especially if you plan pregnancy.

Sources and Further Reading

1. U.S. Department of Health & Human Services, Office on Women’s Health. Uterine fibroids. https://www.womenshealth.gov/a-z-topics/uterine-fibroids
2. American College of Obstetricians and Gynecologists (ACOG). Uterine Fibroids (FAQ). https://www.acog.org/womens-health/faqs/uterine-fibroids
3. U.S. Food and Drug Administration (FDA). Laparoscopic Power Morcellators: Safety information. https://www.fda.gov/medical-devices/surgery-devices/laparoscopic-power-morcellators
4. FDA Press Announcement. FDA approves first oral treatment for management of heavy menstrual bleeding due to uterine fibroids in premenopausal women (elagolix combination). https://www.fda.gov/news-events/press-announcements/fda-approves-first-oral-treatment-management-heavy-menstrual-bleeding-due-uterine-fibroids
5. FDA Press Announcement. FDA approves treatment for heavy menstrual bleeding associated with uterine fibroids in premenopausal women (relugolix combination). https://www.fda.gov/news-events/press-announcements/fda-approves-treatment-heavy-menstrual-bleeding-associated-uterine-fibroids-premenopausal-women

This article is for educational purposes and is not a substitute for personalized medical advice. If you have symptoms or questions about fibroids, consult a qualified healthcare professional.