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Which Size Of Fibroid Is Dangerous? Understand Its Complications!

This article was created after thorough research and has been improved with the assistance of AI technology. Furthermore, our dedicated editorial team has meticulously fact-checked and polished its content for accuracy and clarity.

Uterine fibroids are non-cancerous growths that develop within the muscular walls of the uterus. They are remarkably common, affecting up to 80% of women by age 50. While some women with fibroids experience no symptoms at all, others struggle with pelvic pain, heavy menstrual bleeding, frequent urination, and other life-disrupting issues.

One of the key factors influencing the impact of fibroids is their size. Fibroids can range from minuscule growths the size of a pea to bulky masses larger than a grapefruit. So what size fibroids are considered large? And at what point do they become dangerous? Let’s explore these questions and delve into the world of fibroid sizing and treatment options.

Key takeaways:

Uterine fibroids are non-cancerous growths that develop in the uterus
Fibroids are classified as small (1-5 cm), medium (5-10 cm), or large (>10 cm)
Larger fibroids are more likely to cause symptoms and complications
Fibroid size, number, and location all influence the impact on health
Treatment options depend on fibroid characteristics and patient preferences

Fibroid Size Classifications

Fibroid Size Classifications

Fibroids are often described in relatable terms, compared to fruits, nuts, or sports equipment. However, doctors use more precise measurements, typically noting the length of the fibroid’s longest dimension. Here’s how fibroids are commonly classified by size:

  • Small fibroid: less than 5 cm
  • Medium fibroid: between 5 cm and 10 cm
  • Large fibroid: greater than 10 cm

It’s important to note that size isn’t everything when it comes to fibroids. Even a 2 cm fibroid can cause significant symptoms if it’s located in a problematic spot, like pressing on the bladder or distorting the uterine cavity. However, in general, larger fibroids tend to be more symptomatic and potentially dangerous.

What Is Considered A Large Fibroid?

While 10 cm is the typical cutoff for a large fibroid, there’s no universal agreement on the exact boundary. Some doctors may consider a 6 cm fibroid to be large, while others may not designate a growth as “large” until it reaches 12 cm or more. Essentially, a large fibroid is one that is causing significant symptoms or raising concerns based on its size alone.

It’s not uncommon for fibroids to grow to impressive dimensions. Masses the size of a grapefruit (around 10-12 cm) are often identified and treated. However, in extreme cases, fibroids can become as large as a watermelon, reaching 20 cm or even 30 cm in diameter. The largest fibroid ever removed weighed a staggering 140 pounds! While such giant growths are rare, they illustrate the potential for fibroids to grow unchecked.

Which Size Of Fibroid Is Dangerous?

So when does a fibroid officially become dangerous? There’s no single tipping point, as the risk posed by a fibroid depends on more than just its size. That said, fibroids over 5 cm in diameter are more likely to cause significant symptoms and complications. Here are some key concerns associated with large fibroids:

  • Heavy, prolonged menstrual bleeding leading to anemia
  • Pelvic or back pain and pressure
  • Urinary frequency, urgency, or incontinence
  • Constipation or bloating
  • Pain during intercourse
  • Fertility issues, especially if the fibroid distorts the uterine cavity
  • Pregnancy complications like miscarriage, preterm labor, or placental abruption
  • Fibroid degeneration, where a fibroid outgrows its blood supply and starts to die

In extreme cases, a very large fibroid can even press on the ureters (tubes connecting the kidneys to the bladder) or cause blood clots in the legs. While these severe complications are rare, they highlight the potential dangers of allowing fibroids to grow unchecked.

Specific concerns arise with different fibroid sizes. For example, is a 5 cm fibroid dangerous? At that size, it may cause some symptoms like heavy bleeding or pelvic pressure, but it’s unlikely to pose an urgent threat. However, a 10 cm fibroid is more worrisome, as it’s crossing into the “large” category and has a higher risk of causing significant issues.

How Big Can Fibroids Get?

The short answer is: pretty darn big. While the majority of fibroids are diagnosed when they’re under 10 cm, it’s not unusual for growths to reach 15 cm, 20 cm, or even larger. In general, submucosal fibroids located in the uterine cavity tend to be smaller, as there’s limited room for them to grow. Subserosal fibroids that project outward from the uterus and intramural fibroids embedded in the uterine wall have more space to expand.

So what’s the biggest fibroid ever recorded? That honor goes to a fibroid removed in 2017, weighing 140 pounds and measuring a whopping 33 cm in diameter. For reference, a regulation basketball is about 24 cm in diameter. While this giant fibroid is an extreme outlier, it showcases the growth potential of these tumors.

A more typical “large” fibroid would be in the 10-20 cm range. These growths can cause the uterus to expand to the size of a 4-5 month pregnancy, leading to significant abdominal protrusion. It’s not unusual for a 10 cm fibroid to weigh 1-2 pounds, while a 20 cm growth could easily weigh 10 pounds or more.

Fibroid Size And Treatment Options

Fibroid Treatment

The size of a fibroid is a key factor in determining the best treatment approach. For small fibroids causing no symptoms, a watchful waiting approach is often recommended, with periodic ultrasounds to monitor growth. However, if a fibroid is causing significant issues or rapidly growing, treatment is usually advised.

Medication can help manage symptoms like heavy bleeding, but it won’t shrink fibroids. For that, procedures like uterine fibroid embolization (UFE)[Source: NIH] or MRI-guided focused ultrasound may be recommended. These minimally invasive options work by cutting off the fibroid’s blood supply or destroying its cells with heat, causing the growth to shrink over time.

For larger fibroids, surgery may be the best approach. Myomectomy, which removes the fibroid while preserving the uterus, is an option for women who wish to maintain their fertility. However, if the fibroids are very numerous or large, a hysterectomy (removal of the uterus) may be advised.

The size cutoffs for different treatment options vary, but here are some general guidelines:

  • Fibroids under 5 cm can often be managed with watchful waiting or non-surgical options like UFE.
  • Fibroids between 5-10 cm may require non-surgical intervention or myomectomy, depending on symptoms and fertility goals.
  • Fibroids over 10 cm often require surgery, with myomectomy or hysterectomy being the most common options.

Of course, these are just general guidelines, and the best approach for an individual will depend on their unique circumstances and goals.

See Also: Why Am I Experiencing Weight Gain After Stopping Birth Control?

Symptoms Of Large Fibroids

In addition to tracking fibroid size with imaging, doctors also consider the symptoms a woman is experiencing when determining the best course of action. Large fibroids can cause a range of issues, including:

  • Heavy, prolonged periods: Fibroids can increase menstrual flow and duration, leading to anemia.
  • Pelvic pain and pressure: Large fibroids can cause a feeling of fullness or heaviness in the lower abdomen.
  • Urinary issues: Fibroids pressing on the bladder can cause frequent urination, urgency, or incontinence.
  • Constipation: Fibroids can compress the rectum, leading to constipation and bloating.
  • Pain during sex: Large fibroids can cause discomfort or pain during intercourse.
  • Fertility problems: Submucosal fibroids can distort the uterine cavity and interfere with implantation.
  • Pregnancy complications: Large fibroids can raise the risk of miscarriage, preterm labor, and other issues.

While not all large fibroids cause symptoms, the likelihood of experiencing issues increases with fibroid size. If a woman is experiencing significant symptoms, treatment is usually recommended regardless of the exact dimensions of the fibroid.

Related Reading: Can Birth Control Make You Tired? What The Research Says!

Fibroid Size And Degeneration

Another potential complication of large fibroids is degeneration. This occurs when a fibroid outgrows its blood supply and begins to die. As the cells in the fibroid break down, it can cause acute pain and swelling. Degeneration is most common during pregnancy, as fibroids tend to grow rapidly in response to hormonal shifts.

There are several types of fibroid degeneration, each with its own set of symptoms and imaging characteristics:

The most common type, characterized by a firm, rubbery texture and white or pale appearance on imaging.

Occurs when the fibroid develops fluid-filled pockets, leading to a “cystic” appearance on ultrasound.

A more severe form that occurs when the fibroid outgrows its blood supply rapidly, leading to necrosis and severe pain.

Fibroid degeneration can be managed with pain medication and rest, but in some cases, surgery may be necessary to remove the damaged fibroid.

Fast-Growing Fibroids

Fast-Growing Fibroids

While most fibroids grow slowly over years, some can grow at an alarming rate. A fibroid that grows rapidly or becomes significantly larger over a short period of time is cause for concern. Rapid growth may indicate a more aggressive type of fibroid or even a cancerous growth called leiomyosarcoma (though this is very rare)[Source: Cleveland Clinic].

If a fibroid is growing quickly or causing sudden, severe symptoms, it’s important to see a doctor right away. An ultrasound or MRI can help determine the size and characteristics of the growth and guide treatment decisions.

Further Reading: How Often Should I Change My Tampon For Comfort And Safety

In Conclusion

Fibroid size is a key factor in determining the impact these growths will have on a woman’s health and quality of life. While small fibroids often cause no issues, large fibroids can lead to severe symptoms, fertility problems, and pregnancy complications. Understanding the different size classifications and potential risks can help women make informed decisions about their care.

If you’re experiencing symptoms like heavy bleeding, pelvic pain, or urinary issues, don’t hesitate to speak with your doctor. They can order imaging tests to determine the size and location of any fibroids and recommend the best treatment approach for your unique situation. With proper care and management, even large fibroids can be treated effectively, allowing you to reclaim your health and well-being.


Q1. When do uterine fibroids raise concern?

Fibroids that cause symptoms like heavy bleeding, pelvic pain or pressure, or frequent urination often warrant treatment. Rapidly growing fibroids or those larger than 5 cm in diameter also tend to be more problematic. Fibroids that distort the uterine cavity are especially concerning for women who wish to become pregnant.

Q2. How do fibroids grow?

Fibroids arise from the smooth muscle cells of the uterus and seem to be influenced by estrogen and progesterone. They often grow slowly over time, with an unpredictable pace unique to each woman. Growth tends to accelerate during pregnancy and slow or reverse after menopause.

Q3. Why does fibroid size matter?

Fibroid size correlates with symptom severity and risk of complications. Larger fibroids are more likely to cause bleeding, pain, and abdominal protrusion. They may also press on surrounding organs. In extreme cases, very large fibroids can impair fertility. Size impacts treatment options and helps guide management.

Q4. When should you consider surgical removal of uterine fibroid?

Consider surgery if fibroids are causing significant symptoms, rapidly growing, or very large (over 5-8 cm). Submucosal fibroids often require removal to improve fertility. The approach — myomectomy, UFE, or hysterectomy — depends on number and location of fibroids as well as patient preferences regarding uterine preservation and future pregnancy. Thorough consultation with a gynecologist can clarify the optimal path.


NIH(2023) Uterine Fibroid Embolization Available online at: https://www.ncbi.nlm.nih.gov/books/NBK519016/

Cleveland Clinic(2021) Leiomyosarcoma Available online at: https://my.clevelandclinic.org/health/diseases/22059-leiomyosarcoma

Sara Winslow

Sara Winslow is a board-certified obstetrician-gynecologist with over 15 years of experience in providing comprehensive women's healthcare services. She received her medical degree from Johns Hopkins University School of Medicine, where she graduated with honors. Dr. Winslow completed her residency in obstetrics and gynecology at the prestigious Mayo Clinic, gaining extensive training in various aspects of women's health, including reproductive health, prenatal care, gynecological surgery, and menopause management.

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