Fibroids Size Chart and Fibroids: What to Know

Fibroids Size Chart and Fibroids: What to Know

Uterine fibroids (leiomyomas) are common, benign growths of the muscle tissue of the uterus. While many cause no symptoms, others can lead to heavy menstrual bleeding, anemia, pelvic pressure, urinary frequency, and fertility challenges. Understanding how fibroids are measured and what different sizes can mean helps you make informed decisions about monitoring and treatment.

How Fibroid Size Is Measured

Clinicians typically measure fibroids in millimeters or centimeters using pelvic ultrasound or MRI. You may also hear your clinician describe the overall uterus size as comparable to a certain number of “weeks of pregnancy”—a shorthand for how enlarged the uterus feels on exam. Both approaches are estimates and can vary based on the number of fibroids and their location.

Fibroids Size Chart (Approximate)

There is no single official size chart, but the following ranges are widely used in clinical conversations. Remember: symptoms depend on both size and location.

  • Very small (sub-centimeter): <1 cm (<0.4 in) — often no symptoms; may be seen incidentally on ultrasound.
  • Small: 1–2 cm (0.4–0.8 in) — can contribute to heavy bleeding if submucosal (within the cavity).
  • Medium: 2–5 cm (0.8–2 in) — bleeding or pressure symptoms possible depending on location.
  • Large: 5–10 cm (2–4 in) — more likely to cause bulk symptoms (pelvic pressure, urinary frequency, constipation).
  • Very large: >10 cm (>4 in) or uterus enlarged to >~12-week size — higher chance of noticeable pressure and visible abdominal distension.

Common “everyday” comparisons sometimes used to visualize size:

  • Pea: ~5 mm
  • Grape: ~1–2 cm
  • Walnut/Plum: ~3–4 cm
  • Lime/Lemon: ~5–6 cm
  • Orange: ~7–8 cm
  • Grapefruit: ~9–10+ cm

Note: These comparisons are rough guides. The effect on your health depends not only on size, but also on number and location of fibroids.

Location Matters: Types of Fibroids

  • Intramural: Grow within the muscular wall; can enlarge the uterus and cause heavy bleeding or pain.
  • Submucosal: Project into the uterine cavity; even small ones can cause heavy or prolonged periods and fertility issues.
  • Subserosal: Project outward from the uterus; more likely to cause pressure on bladder or bowel than heavy bleeding.
  • Pedunculated: Attached by a stalk; can twist and cause acute pain.

Symptoms by Size and Location

  • Bleeding symptoms (menorrhagia): More common with submucosal or large intramural fibroids; may lead to iron-deficiency anemia (fatigue, shortness of breath, dizziness).
  • Bulk symptoms: Pelvic pressure, low back pain, urinary frequency/urgency, constipation, and painful intercourse are more likely with larger or multiple fibroids, particularly subserosal.
  • Fertility and pregnancy: Submucosal fibroids can disrupt implantation and increase miscarriage risk. Large intramural fibroids may affect fertility or pregnancy position depending on size and distortion of the cavity.

Diagnosis and Monitoring

  • Pelvic exam: May detect an enlarged or irregular uterus.
  • Ultrasound: First-line imaging to measure fibroid number, size, and location.
  • MRI: Provides detailed mapping, useful when planning procedures like uterine artery embolization or myomectomy.
  • Labs: Complete blood count to check for anemia if heavy bleeding is present.

Stable, small fibroids without symptoms are often monitored with periodic exams and imaging. Rapid growth, severe or worsening symptoms, or uncertainty about diagnosis merits further evaluation.

Treatment Options: Matching Symptoms, Size, and Goals

Management is individualized and depends on your symptoms, fibroid size and location, overall health, and plans for future pregnancy.

Medication (non-surgical)

  • Hormonal birth control: Pills, patch, ring, or the levonorgestrel intrauterine system can reduce heavy bleeding and cramping. They do not permanently shrink fibroids.
  • Tranexamic acid: A non-hormonal option taken during menses to reduce bleeding.
  • GnRH receptor modulators: Short-term therapies that reduce estrogen and progesterone can shrink fibroids and control bleeding. FDA-approved options for heavy menstrual bleeding due to fibroids include combination therapies with elagolix or relugolix (with add-back hormones) to help limit bone loss and menopausal side effects. GnRH agonists (such as leuprolide) are also used short-term, often to improve anemia or shrink fibroids before surgery.

Medication is best for bleeding control and temporary size reduction; fibroids typically regrow after stopping therapy.

Uterus-sparing procedures

  • Myomectomy: Surgical removal of fibroids while preserving the uterus; can be hysteroscopic (for submucosal fibroids), laparoscopic/robotic, or open depending on size and number.
  • Uterine artery embolization (UAE): Interventional radiology procedure that blocks blood flow to fibroids, shrinking them and reducing bleeding and pressure symptoms.
  • Radiofrequency ablation (RFA): Uses heat to shrink fibroids via laparoscopic or transcervical approaches.
  • MRI-guided focused ultrasound (MRgFUS): Noninvasive focused ultrasound energy to ablate fibroid tissue in select candidates.

Definitive treatment

  • Hysterectomy: Removal of the uterus eliminates fibroids and their recurrence; not appropriate for those planning future pregnancy.

Your clinician will review benefits, risks, recovery time, and effects on fertility and menopause timing (ovaries can often be preserved) when considering each option.

When Does Size Change the Plan?

  • Small, asymptomatic fibroids: Watchful waiting with periodic check-ins is common.
  • Medium to large fibroids with heavy bleeding: Medical therapy, hysteroscopic resection (if submucosal), myomectomy, UAE, or other minimally invasive options may be appropriate.
  • Very large fibroids or uterus: May require advanced minimally invasive surgery or, in some cases, open surgery. Pre-treatment with GnRH therapies can sometimes reduce size to expand options.
  • Fertility priority: Submucosal and some intramural fibroids affecting the cavity are often removed via hysteroscopic or laparoscopic myomectomy.

Do Fibroids Shrink on Their Own?

Fibroids are hormone-sensitive and often shrink after menopause as estrogen and progesterone levels fall. In the years leading up to menopause (perimenopause), bleeding patterns may still be heavy or irregular. Lifestyle measures—maintaining a healthy weight, treating anemia, and monitoring symptoms—support overall health but do not reliably shrink fibroids.

Safety, Risks, and Rare Concerns

  • Cancer risk: Fibroids are benign. A different, rare tumor called leiomyosarcoma can present similarly; unexpected sarcoma at surgery is uncommon. Imaging and clinical history guide decision-making, but sarcoma cannot be definitively diagnosed without pathology.
  • Anemia: Heavy bleeding can cause iron-deficiency anemia. If you have fatigue, shortness of breath, or dizziness, ask about a blood count and iron studies.
  • Pregnancy: Many people with fibroids have healthy pregnancies. Depending on size and location, there may be higher risks of pain from degeneration, malpresentation, or cesarean delivery; individualized care is important.

When to See a Clinician

  • Periods lasting more than seven days or soaking through protection in under two hours.
  • Symptoms of anemia (fatigue, pale skin, dizziness) or documented low hemoglobin.
  • Pelvic pressure, urinary frequency, constipation, or pain that affects daily activities.
  • Difficulty getting pregnant or recurrent pregnancy loss.
  • Rapidly enlarging abdominal or pelvic mass.

This article is for general education and not a substitute for personalized medical advice. A gynecologist or fibroid specialist can help tailor monitoring and treatment to your goals.

Trusted Sources and Further Reading

  • National Institutes of Health (NIH) MedlinePlus: Uterine Fibroids — https://medlineplus.gov/uterinefibroids.html
  • Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): Uterine Fibroids — https://www.nichd.nih.gov/health/topics/uterine
  • American College of Obstetricians and Gynecologists (ACOG): Uterine Fibroids FAQ — https://www.acog.org/womens-health/faqs/uterine-fibroids
  • U.S. Food and Drug Administration (FDA): Oriahnn (elagolix, estradiol, norethindrone acetate) — https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/oriahnn
  • U.S. Food and Drug Administration (FDA): Myfembree (relugolix, estradiol, norethindrone acetate) — https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/myfembree
  • MedlinePlus: Uterine Artery Embolization for Fibroids — https://medlineplus.gov/ency/article/007421.htm

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