What Are Uterine Fibroids? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Uterine fibroids are abnormal tissue growths in the wall of the uterus that are almost always noncancerous but can be hard to live with.

Fibroids are quite common among women of reproductive age, and as many as 4 in 5 women develop fibroids by the time they’re 50. Fibroids can grow as a single mass or develop in several parts of the uterine cavity at once, and range in size from a tiny seed to a giant grapefruit.

The size, number, and location of fibroids can make a big difference in symptom severity and treatment approaches. Some women never experience symptoms or require treatment for fibroids. For others, symptoms such as heavy and painful menstrual bleeding, lower back pain, and pain during sex can be persistent and disabling. Fibroids are also associated with reproductive health problems, such as an increased risk of infertility, preterm labor, and cesarean section deliveries.

If you’re experiencing symptoms — even if you have issues that seem unrelated to reproductive health — it’s important to see a gynecologist for a pelvic exam. Doctors can feel these masses during an internal exam and confirm a diagnosis of uterine fibroids with an ultrasound. Depending on the circumstances, treatment options may include medication to manage symptoms or minimally invasive surgery to remove the fibroids.

Scientists aren’t entirely certain what causes uterine fibroids, but hormones and genetics are thought to play a role. Some studies have identified genetic differences between fibroid masses and normal tissue in the uterus. Other research suggests that the sex hormones estrogen and progesterone — responsible for causing the uterine lining to grow during monthly menstrual cycles in preparation for a pregnancy — may fuel fibroid growth.

While all women of reproductive age can develop fibroids — and many of them do — there are other factors that affect the odds of this happening.

• Race Black women are more likely to develop fibroids, experience them at younger ages, and have more debilitating symptoms. One study found Black women are three times more likely to have fibroids, as well as much more apt to have larger masses and multiple tumors. In another study, published in July 2022 in the Journal of Minimally Invasive Gynecology, researchers examined the health records of 1,311 women who underwent surgery for uterine fibroids between 2015 and 2020 at Cedars-Sinai. They found that most patients received a minimally invasive procedure to remove either fibroids or the uterus. But the data also revealed racial gaps in care. The researchers found that 81 percent of white women included in the review underwent a minimally invasive procedure, compared with only 57 percent of Black women and 65 percent of Hispanic women.
• Family history Women who have a mother or sister with fibroids are much more likely to develop them. One study found family history roughly doubles the risk.
• Diet Certain eating habits can increase the risk of fibroids, including consuming lots of red meat and alcohol as well as eating too few green vegetables and fruits.
• Age at menarche (first period) Women who start menstruation earlier are more likely to have uterine fibroids, possibly because of increased exposure to estrogen over the years, some research suggests.
• Weight Being overweight or obese is associated with an increased risk of uterine fibroids. Research suggests that fat tissue is associated with higher estrogen levels, which may contribute to tumor growth.

Even when women have none of these common risk factors, they can still develop fibroids. There are no foolproof ways to prevent these growths, although there are numerous other benefits to maintaining a healthy body weight and eating a plant-based diet.

Many women with uterine fibroids get diagnosed during a routine pelvic exam when a doctor feels something irregular in the shape of the uterus. Not all women will have symptoms when fibroids are suspected during an exam.

If something does feel amiss during the pelvic exam or if patients complain of symptoms like intense menstrual pain or unusually heavy periods, there are several tests that doctors can do to determine whether fibroids are in fact the culprit and, if so, the size and location of any masses in the uterine cavity.

• Ultrasound You may get a transabdominal ultrasound — with a device placed over your stomach — or a transvaginal ultrasound — with a wand inserted into your vagina — to get images of the uterus. This helps doctors confirm whether uterine fibroids are present, where they’re located, and how large they are.
• Blood tests You may also get blood tests to rule out any other possible causes of your symptoms, particularly if you’re experiencing anemia.
• Advanced imaging Sometimes an ultrasound is insufficient to map out fibroids inside the uterus. In these cases, doctors may use more advanced imaging such as a magnetic resonance imaging (MRI) scan, sonograms done after saline is infused into the uterus to expand the cavity and make it easier to see fibroids, or X-rays done after injecting special dyes to enhance images of the uterus.

The prognosis depends on the size, number, and location of uterine fibroids as well as how fast they grow and what symptoms they’re causing. For some women, doctors advise what’s known as watchful waiting — just getting periodic exams — for fibroids that aren’t causing symptoms or growing aggressively. Other women may go through several decades of treatments to manage severe symptoms and recurring growths in the uterus.

Treatment for uterine fibroids can involve medication to manage symptoms as well as surgical procedures to remove tumors. The best options for individual patients will depend on the severity of their symptoms, the amount of fibroid tissue in the uterus, and whether they want to become pregnant in the future.

Medication Options

Medications can temporarily ease symptoms but will not eradicate these growths. According to UCSF Health, medicines to manage fibroid symptoms include:

• Hormonal contraceptives Birth control pills, or hormonal birth control in general, can sometimes help reduce heavy bleeding and menstrual pain. Intrauterine devices (IUDs) are a long-acting form of contraception that can also release a small amount of hormone into the uterus and curb heavy menstrual bleeding caused by fibroids.
• Hormone blockers Medicines known as GnRH agonists (Lupron, Eligard) work by blocking production of sex hormones, which can reduce the amount of estrogen available to fuel fibroid growth. These drugs can temporarily shrink fibroids and may be prescribed before surgery in order to make larger tumors smaller and easier to remove.
• Combination therapy Myfembree is a combination of three medications: relugolix (a hormone blocker), estradiol (estrogen), and norethindrone acetate (a synthetic progesterone). It relieves heavy bleeding caused by fibroids.
• Anti-inflammatory drugs Pain relievers known as nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen may be prescribed to ease pain caused by fibroids.

Surgery is the only way to remove fibroids; the more conservative options that are preferred by many patients to preserve fertility can’t prevent future fibroid growth, according to John Hopkins Medicine. Less invasive, uterine-preserving surgical options that leave women with an intact uterus that can carry a baby include:

• Myomectomy This procedure involves removing fibroids but leaving the uterus intact. Doctors may cut into the abdomen to perform a traditional “open” myomectomy; use minimally invasive techniques to access the uterus through tiny abdominal incisions; or insert a camera into the vagina to find and shave down visible fibroid tissue.
• Uterine artery embolization (UAE) This minimally invasive procedure uses X-rays to identify major arteries feeding into fibroids, then cuts off the blood flow to the tumors so that they shrink.
• Radiofrequency ablation This is a newer option that uses ultrasound images to locate fibroids, then heats them to make them softer and smaller.
• MRI-guided ultrasound surgery This approach uses ultrasound waves through the skin to destroy fibroids. More evidence is still needed to determine how effective this is. The impact of MRI-guided ultrasound surgery on fertility and pregnancy is also unknown.
• Surgical removal of uterus For women with more debilitating or severe symptoms or aggressive fibroid growth in terms of the size or number of masses, a more aggressive approach may be warranted: a procedure known as a hysterectomy that removes the entire uterus. After a hysterectomy, a woman does not have a menstrual period and cannot become pregnant. Fibroids are the most common reason why women get hysterectomies.

While it’s rare for fibroids to have severe complications, there are some serious health issues that can result from these masses. One of the most common problems resulting from fibroids is anemia, or a lack of red blood cells, which left untreated can lead to fatigue, dizziness, shortness of breath, or a rapid heartbeat.

Other complications that are less common are related to the location and size of fibroids. Larger masses that grow too close to the bladder, such that they interfere with the normal process of emptying urine from the kidneys, can lead to kidney damage. Bigger tumors that grow near the cervix can contribute to pregnancy loss and preterm labor.

Fibroids are also associated with an increased risk of infertility and cesarean section deliveries.

Another common symptom of uterine fibroids — heavy or irregular menstrual bleeding — can be caused by several other conditions, according to Mount Sinai. Unusual or irregular vaginal bleeding might be due to fluctuations in hormone levels, certain sexually transmitted infections, irregular thyroid function, inflammation in the cervix or uterus, or cancer.

Fibroids are almost always noncancerous and don’t increase the risk of uterine cancer. Cancerous fibroids (leiomyosarcoma) are rare — fewer than 1 in 1,000, per the Office on Women’s Health, which notes that doctors don’t think these cancers develop from an already existing fibroid.