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Fibroid facts

Uterine Fibroids Facts

What Are fibroids?

Uterine fibroids - also called leiomyomas - are extremely common benign smooth muscle tumors of the uterus. They arise in reproductive-age women and typically present with symptoms of abnormal uterine bleeding, pelvic pain, and/or pelvic pressure.

Uterine fibroids diagram

How Common Are Fibroids?

While the exact percentage of women living with fibroids (the prevalence of the condition) is unknown, fibroids are an undeniably common condition. One of the reasons why it is difficult to estimate the prevalence of fibroids is that many women living with fibroids are asymptomatic. Estimates of true prevalence range anywhere from 5% to 21% of all women.¹

Black women in Los Angeles sunset

Risk factors are patient characteristics, both modifiable (such as diet) and non-modifiable (such as race), that increase the individual's’ risk of developing uterine fibroids. Two clearly established risk factors for uterine fibroids are age and race. Other risk factors include obesity, family history, lifestyle, and diet.²

Are Some Women at Higher Risk of Fibroids Than Others?

Woman with fibroids holding pelvis

Types of Fibroids

Fibroids are commonly classified based on their size and location relative to the uterus. They can grow in the wall of the uterus (intramural), on the outside of the uterus (subserosal), underneath the uterine lining (submucosal), and/or on small stalks inside or outside of the uterus (pedunculated).³

Types of fibroids diagram

A malignant tumor of the smooth muscle is termed a leiomyosarcoma. Thankfully, a number of studies have looked at the rate of leiomyosarcoma findings in women with pelvic tumors, and the review consensus is that about 1 in 400 women (0.25%) undergoing surgery for fibroids is at risk of having a leiomyosarcoma.⁴

Are Fibroids Cancerous?

Woman consulting doctor about fibroids and cancer

Symptomatic fibroids negatively impact quality of life. Symptoms of uterine fibroids can vary widely depending on number, location, and size of fibroids in the affected individual. Some women are completely asymptomatic while others experience heavy menstrual bleeding, chronic pelvic discomfort, and fertility challenges.

Symptoms of Uterine Fibroids

Woman in pain and discomfort from fibroids


[1] Zimmermann, A., Bernuit, D., Gerlinger, C., Schaefers, M., & Geppert, K. (2012). Prevalence, symptoms and management of uterine fibroids: An international internet-based survey of 21,746 women. BMC Women’s Health, 12(1), 6.

[2] Pavone D et al. Epidemiology and Risk Factors of Uterine Fibroids. Best Pract Res Clin Obstet Gynaecol. 2018 Jan; 46:3-11.

[3] Stewart, E. A. (2001). Uterine fibroids. The Lancet, 357(9252), 293–298.

[4] Seagle, B. L. L., Alexander, A. L., Strohl, A. E., & Shahabi, S. (2018). Discussing sarcoma risks during informed consent for nonhysterectomy management of fibroids: an unmet need. American Journal of Obstetrics and Gynecology, 218(1), 103.e1-103.e5.

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