What Are Subserosal Fibroids?

Medically reviewed by Peter Weiss, MD

Subserosal fibroids are noncancerous growths on the outside of the uterus. Most subserosal fibroids are asymptomatic; however, symptoms can include pelvic or abdominal pain, constipation, a feeling of fullness in the abdomen, and an increased need to urinate.

Researchers don’t know the exact cause of subserosal fibroids, but the hormones estrogen and progesterone likely play a role in their development. Risk factors such as a family history of uterine fibroids, obesity, being of African descent, and older age increase your chance of developing them. Uterine fibroids are common and approximately 70% of people with uteruses will develop one by age 50.

Treatment for subserosal fibroids is usually only recommended for individuals whose quality of life is impacted by their fibroids. The definitive treatment for subserosal fibroids is a hysterectomy or the complete surgical removal of the uterus. For individuals wishing to preserve their fertility or uterus, additional therapeutic options are available.

Symptoms

Uterine fibroids are most common in people with uteruses between 40-50 years old and it is estimated that only 20-50% of uterine fibroids cause symptoms. Unlike other uterine fibroid types, subserosal fibroids don’t usually cause excessive bleeding, anemia (low red blood cell count), or pregnancy complications.

Subserosal fibroids can vary in number and size. They can grow directly out of the uterus or can be “pedunculated,” which is when the fibroid is attached to the uterus by a stem-like structure. Because of these features, people with subserosal fibroids may experience the following symptoms:

• Pelvic or abdominal pain

• Constipation

• Feeling of fullness in the abdomen

• Pain or discomfort during sex

• Frequent need to urinate

• Lower back or leg pain

The severity of symptoms depends on the size, location, and number of fibroids. For people with pedunculated subserosal fibroids, severe pain, fever, and nausea may occur if the stem-like structure becomes twisted, although this is a rare occurrence. Clinically, this is called pedunculated subserosal leiomyoma with torsion.

Because fibroids are common, you may have multiple fibroid types at the same time and experience other symptoms in addition to those common for subserosal fibroids.

What Causes Subserosal Fibroids?

Researchers don’t know the exact cause of subserosal fibroids, but the hormones estrogen and progesterone likely play a role in their development. You may see changes in your fibroids during periods of hormone changes. Fibroid size usually decreases after menopause, when the concentration of these hormones in the body decreases. You may also see changes in your fibroids during pregnancy, although these changes vary from person to person.

Although 70% of people with uteruses will experience a uterine fibroid by the age of 50, some risk factors can increase your chance of developing the condition:

• Age: Uterine fibroids mostly occur between puberty and menopause; however, you are most at risk between the ages of 40-50 years old.

• Ethnicity: Uterine fibroids are more common in individuals of African descent.

• Body composition: Having excess abdominal visceral fat increases your chance of developing uterine fibroids.

• Birth history: Your risk increases if you have never given birth to a child.

• Age of first menstruation: If you went through puberty at a young age (i.e., began menstruation early) you have a higher risk of developing uterine fibroids.

• Genetics: A family history of uterine fibroids increases your risk.

Diagnosis

Diagnosing subserosal fibroids can be more challenging than other uterine fibroid types. Uterine fibroids that grow inside the uterus may be discovered during your annual pelvic exam at your gynecologist (a medical doctor who specializes in treating conditions that affect the uterus, vagina, and ovaries) and are usually associated with changes in your menstrual cycle. Subserosal fibroids, however, require diagnostic imaging because they grow on the outside of the uterus and symptoms alone may not clearly indicate a subserosal fibroid diagnosis.

In addition to your medical history and any symptoms you are experiencing, your healthcare provider may perform the following diagnostic tests:

• Transabdominal ultrasound: An ultrasound wand is pressed against your abdomen to visualize your uterus and pelvis.

• Transvaginal ultrasound: An ultrasound wand is inserted through your vagina to visualize your uterus and pelvic region in areas not possible through a transabdominal ultrasound.

• Contrast sonohysterography: In this test, a small amount of saline is injected into your uterus to help create a better ultrasound image.

• Laparoscopy: A healthcare provider creates a small incision in your abdomen and then visualizes the uterus through a small device.

• CT scan or MRI: A computerized tomography (CT) scan and magnetic resonance imaging (MRI) are advanced imaging techniques that may be used to create more detailed imaging of your uterus and pelvis.

Although there are many different imaging tests available to help diagnose subserosal fibroids, the most common tests used are the transabdominal and transvaginal ultrasound. Biopsies (which involve taking a small sample of tissue to examine for abnormal cells) of subserosal fibroids are not taken unless your healthcare provider wants to rule out possible uterine cancer. Biopsies are rarely performed because subserosal fibroids is considered a benign condition, meaning that it is not cancerous.

Treatment For Subserosal Fibroids

Many people are unaware that they have subserosal fibroids because most cases of uterine fibroids are asymptomatic. Those who typically seek treatment for subserosal fibroids do so because their quality of life is impacted by their symptoms. Therefore, treatment goals for subserosal fibroids are focused on reducing symptom severity.

The only definitive treatment for subserosal fibroids is a hysterectomy, or the complete surgical removal of the uterus. There are alternative treatments available for individuals wishing to have children or keep their uterus; however, fibroids may return after treatment. Your healthcare provider will recommend the best course of treatment based on your preference for preserving fertility and the location, size, and number of fibroids.

Surgical Therapies

The most effective surgical treatment for subserosal fibroids is a hysterectomy. However, several other surgical options are available to remove or reduce the size of subserosal fibroids. Surgical options that preserve the uterus include:

• Myomectomy: This is a surgical procedure that removes the fibroid while preserving the uterus. After five years, between 15 and 30% of people who have this procedure will have their fibroids come back.

• Uterine artery embolization (UAE): This is a surgical procedure that cuts off the blood supply to the fibroid to help reduce its size. After 30 months, more than 17% of people will have their fibroids come back.

Drug Therapies

Hormones play a role in the growth and development of uterine fibroids. The use of hormone-related treatments is typically reserved for individuals with fibroids that are located inside the uterus and cause changes in menstruation. However, they may also be used for subserosal fibroids in some cases. These therapies include:

• Selective progesterone receptor modulators, a type of hormone treatment that temporarily reduces the size of uterine fibroids by changing the concentration of progesterone in your body. This therapy may be used to reduce fibroid size before other surgical treatments or menopause.

• Gonadotropin-releasing hormone analogues, a type of hormone treatment that temporarily reduces the size of uterine fibroids by changing the concentration of multiple hormones in your body. This therapy may be used to reduce fibroid size before other surgical treatments or menopause.

• Progestin-releasing intrauterine devices (IUDs), a type of hormone treatment and birth control method that can help decrease blood loss and reduce pain associated with menstruation.

Prevention

Researchers and healthcare professionals have not been able to pinpoint specific actions you can take to prevent the development of subserosal fibroids. Most risk factors associated with an increased risk of developing uterine fibroids cannot be changed.

However, having your annual gynecological exam and maintaining a healthy lifestyle (e.g., eating a balanced diet and staying active) can help support your overall health. Plus, establishing an active line of communication with your gynecologist or primary care physician can help them find a diagnosis and treatment earlier if you begin to experience symptoms.

Complications

Most subserosal fibroids are asymptomatic and do not cause complications. However, the size, number, and location of fibroids are unique to each person and complications can occur.

Compared to other types of uterine fibroids, subserosal fibroids are not usually associated with pregnancy complications or heavier bleeding during menstruation. Subserosal fibroids may impact other organ functions (such as the bowel and bladder) if they apply too much pressure on these organs.

Rarely, pedunculated subserosal fibroids may cause sudden, severe pain if the stem-like structure that connects the fibroid to the uterus becomes twisted.

Living With Subserosal Fibroids

Life with subserosal fibroids will vary greatly from person to person. Most people are unaware that they have subserosal fibroids. However, subserosal fibroids can affect your quality of life, especially if the fibroids cause symptoms. In a study of more than 20,000 people living with symptomatic subserosal fibroids, 43% reported that their fibroids impacted their sex life, 28% reported that their fibroids impacted their performance at work, and 27% reported that their fibroids impacted their family life.

Luckily, there are several treatment options to reduce symptom severity for individuals living with subserosal fibroids. For those seeking a definitive treatment, a hysterectomy is available.

Frequently Asked Questions

How serious is a subserosal fibroid?

Subserosal fibroids are almost always a benign, or noncancerous, condition. Most cases of subserosal fibroids are asymptomatic, but symptoms such as pain, constipation, and a more frequent need to urinate are possible. If necessary, subserosal fibroids can be cured by a hysterectomy or improved through alternative treatments.

When should subserosal fibroids be removed?

Subserosal fibroids should be removed if they hurt your quality of life and/or cause other health complications.

Can fibroids come out as clots?

Subserosal fibroids cannot come out as clots during menstruation because they grow on the outside of the uterus.

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