A fibroid is a very common, noncancerous tumor that grows in the uterus. They can be tiny or very large, and it’s possible to have several fibroids at once. Fibroids frequently grow without causing any symptoms or requiring any treatment.

But in rare cases, a mass in the uterus that was thought to be a fibroid actually turns out to be cancerous. In these cases, immediate treatment is needed. Typically, this involves surgery, followed by possible chemotherapy or radiation.

This article takes a closer look at fibroids, including symptoms, causes, treatment, and outlook.

Types of uterine fibroidsShare on Pinterest
Types of uterine fibroids. Illustration by Jason Hoffman

Fibroids are a type of tumor that develops in the uterus. They’re made of fibrous connective tissue and smooth muscle cells.

Fibroids are very common and are not cancerous. Fibroids don’t increase the risk of cancer. In fact, many types of fibroids don’t cause any symptoms or require any treatment at all.

But very rarely, a mass in the uterus that was thought to be a fibroid turns out to be cancerous. This occurs in less than 1 in 1,000 fibroids. These rare tumors are called leiomyosarcoma, a type of cancer that grows in smooth muscle tissue.This rare type of fibroid needs immediate removal.

It’s very common for fibroids not to cause any symptoms at all. But large fibroids, or large numbers of fibroids, can cause symptoms. Small fibroids can also cause symptoms if they’re located in the uterine cavity.

Symptoms may include:

Cancerous tumors in the uterus can also cause these same symptoms. Frequently (though not always), the primary difference between cancerous tumors and fibroids is that they’ll look different on imaging tests.

When should you seek emergency treatment?

Fibroids can become a medical emergency. This is very rare, but possible. Fibroids can shed and cause severe, rapid blood loss. If you experience heavy bleeding, it’s important to seek urgent medical care.

Was this helpful?

The exact cause of fibroids isn’t known. But researchers have observed that they often run in families. It’s very likely there’s a genetic link, but researchers don’t know for certain what that link is.

There are several known risk factors. These factors make it more likely that you’ll develop fibroids in your lifetime. They include:

  • Obesity: Having overweight or obesity increases the risk of fibroids.
  • Age: Until menopause, your risk for fibroids increases as you age. After menopause, your risk decreases.
  • Family history: You’re more likely to develop fibroids if a family member had fibroids. If your mother had fibroids, your risk is 3 times higher than average.
  • Ethnicity: In the United States, Black women are more likely to develop fibroids than any other racial or ethnic group.

Asymptomatic fibroids (those without symptoms) may be found during a routine exam.

They can often be felt under the skin as a hard lump when a doctor is conducting a pelvic exam. They may also be discovered during an imaging test for another condition.

If you come to your doctor with symptoms, or if your doctor suspects fibroids after a physical exam, they’ll likely order an imaging test. Typically, this will be a pelvic ultrasound.

During a pelvic ultrasound, a small ultrasound probe is placed on the abdomen or inside the vagina so that clear images of the pelvic region can be created.

In some cases, you might also have an MRI. An MRI can create detailed images of the exact size and number of fibroids. It’s also a good way to distinguish fibroids from other similar conditions, like adenomyosis.

Typically, these tests are enough to diagnose fibroids. They can also be used to distinguish cancerous tumors from fibroids because cancerous tumors look different in imaging results.

If the results are not clear enough, or if more information is needed, additional imaging tests might be done.

Fibroids vs. uterine sarcoma

Uterine sarcoma is a rare cancer that develops in the muscle surrounding the uterus. It can cause symptoms that are similar to fibroids or other cancerous tumors, but it’s a different type of cancer entirely.

Whether you have a fibroid, a uterine sarcoma, or another type of cancerous tumor, your next steps will be similar. You’ll have a biopsy to confirm a diagnosis.

If cancer is found, you’ll likely have surgery to remove the tumor.

You and your medical team will discuss the surgical treatment that will most effectively treat your cancer while, if possible and if desired, preserving fertility options. You might then have chemotherapy or radiation after surgery to destroy any remaining cancer cells.

Was this helpful?

Treatment for fibroids depends on several factors. In a large percentage of cases, no treatment is required at all. It’s generally believed that fibroids do not become cancerous, and most fibroids do not cause symptoms.

Additionally, fibroids may stop growing and may even shrink as menopause approaches due to a decreased release of estrogen and progesterone. But this is not always the case.

For these reasons, doctors may recommend observation as the treatment plan for fibroids. This means that your doctor will keep an eye on the fibroids via future imaging tests. You’ll also be asked to report any new symptoms.

Conversely, if your doctor suspects you have a sarcoma and not a fibroid, you’ll have surgery to remove it. The exact type of surgery will depend on the size and location of the tumor.

You and your doctor might discuss ways to preserve as much surrounding uterine tissue as possible so that fertility is not affected.

After surgery, you might have chemotherapy and radiation to remove any remaining cancer cells.

In some cases, fibroids do require treatment. This normally includes fibroids that are:

  • large
  • causing symptoms
  • growing rapidly
  • very numerous

Treatments options in these instances include:

  • Medications to shrink fibroids: Medications that shrink fibroids like Gonadotropin-releasing hormone (GnRH) agonists.
  • Oral birth control: Oral birth control medication doesn’t shrink fibroids, but it can stop menstrual bleeding. Your doctor might recommend it for symptom management.
  • Pain medication: Your doctor might recommend medications to help manage pain. They might suggest an over-the-counter nonsteroidal anti-inflammatory drug (NSAID) or order a prescription-strength NSAID.
  • MRI-guided focused ultrasound surgery (FUS): FUS is a noninvasive option that uses an MRI scanner to locate fibroids and then heat and destroy the fibrous tissues with a small transducer. FUS is a newer treatment option and is not available everywhere.
  • Uterine artery embolization. Uterine artery embolization is a method where small particles called embolic agents are injected into the arteries. These agents cut off blood flow to the fibroids, causing them to shrink and die.
  • Radiofrequency ablation. This procedure uses radiofrequency waves to destroy the fibroids. It can be done using a heated needle that kills the fibroid or by freezing and destroying the fibroid.
  • Myomectomy. A myomectomy is a surgical procedure to remove fibroids. There are a few different surgical options for this, including removal via laparoscopic surgery, traveling up the vagina and cervix to remove the fibroids in a hysteroscopic procedure, or through a traditional incision in an abdominal procedure.
  • Endometrial ablation. This procedure uses a specialized tool that’s inserted into the uterus. The tool uses heat and microwave energy to destroy the lining of the uterus. This procedure isn’t a specific fibroid treatment, but it can help treat abnormal uterine bleeding associated with fibroids.
  • Hysterectomy. A hysterectomy is a surgery to completely remove the uterus. This procedure is a permanent cure for fibroids, but it also results in full infertility. For some women with fibroids, this isn’t a concern, but for others, this can be an extremely personal and difficult choice.

Fibroids are benign (noncancerous) tumors. Most fibroids cause no symptoms, don’t require treatment, and are not a serious health concern.

Even when fibroids are causing symptoms, they can typically be addressed and managed with noninvasive treatments or surgery.

Are fibroids dangerous?

Fibroids are not dangerous. In very rare cases, fibroids can be dangerous if they bleed or are very large and compress other structures within the pelvis. But this is not a common occurrence.

It’s also possible for symptoms of fibroids, like heavy menstrual bleeding, to lead to additional complications like anemia. If fibroids are causing additional symptoms, a doctor can help you manage them.

Can fibroids harm my pregnancy?

Most people experience no harmful effects from fibroids during their pregnancy. But a 2010 study found that 10% to 30% of people with uterine fibroids develop complications during pregnancy.

According to this study, the most common complication is pain, particularly in people who have fibroids larger than 5 centimeters. Fibroids may also increase your risk for:

If you’re pregnant or considering getting pregnant, talk with your doctor about fibroids. Your doctor will take into account the number of fibroids you have, along with their size and location, to determine the best course of action.

Can fibroids affect my chances of getting pregnant?

There isn’t a proven link between fibroids and infertility, but some studies have shown there might be a connection. It’s a good idea to talk with your doctor about this possible link.

Is there anything you can do to prevent fibroids?

Researchers don’t know what causes fibroids, so there’s no way to say what might prevent them. But we do know what increases the risk for fibroids. Avoiding these risk factors won’t prevent fibroids, but it can lower your risk.

Steps you can take include:

Fibroids are a common, benign (noncancerous) type of tumor that grows in the uterus. Most fibroids cause no symptoms and do not require treatment.

While it’s not possible for fibroids to become cancerous, a very small percentage of masses that initially appear to be fibroids are actually cancerous. These tumors need to be removed quickly before the cancer spreads.