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Fibroids in the uterus are tumors that develop in or on the walls of the uterus. They are common and not typically cancerous.
Fibroids in the uterus, or uterine fibroids, are the most common noncancerous, or benign, tumors in people of childbearing age. They are also known as leiomyomas and myomas.
Many people have fibroids with no symptoms, whereas others experience pain, bleeding, or both.
This article provides an overview of fibroids, including their types, effects on the body, causes, and treatment options.
Uterine fibroids are growths in or on the walls of the uterus. They consist of smooth muscle cells and connective tissue.
A person may have one or multiple fibroids. They can be as small as an apple seed or as big as a grapefruit (or sometimes even larger than that). They can also shrink or grow over time.
Fibroids are more common from age 30 to the age at which menopause begins. They usually shrink after menopause. Between 20% and 80% of females develop fibroids by the age of 50, according to the Office on Women’s Health (OWH).
It is unclear exactly why they form, but they seem to develop when estrogen levels are higher.
Uterine fibroids are almost always noncancerous. The OWH also say that cancerous fibroids are rare, occurring in fewer than 1 in 1,000 cases. However, other sources suggest that they may be more common than this.
When a fibroid is cancerous, it is called a leiomyosarcoma.
Having preexisting fibroids do not increase the risk of developing a leiomyosarcoma.
The classification of a fibroid depends on its location in the uterus.
The three main types of fibroid are:
- Subserosal fibroids: These are the most common type. They grow on the outside of the uterus.
- Intramural fibroids: These grow inside the muscular wall of the uterus.
- Submucosal fibroids: These grow into the open space inside the uterus.
Some fibroids can become pedunculated fibroids, which means that the fibroid has a stalk that attaches to the uterus.
Most fibroids do not cause any noticeable symptoms. However, some can cause significant discomfort.
The symptoms of uterine fibroids can include:
- heavy periods, also known as menorrhagia, which can lead to anemia
- painful periods
- lower backache or leg pain
- discomfort or a feeling of fullness in the lower abdomen, especially in the case of large fibroids
- frequent urination
- pain during sexual activity, also known as dyspareunia
Some people may have fertility problems associated with fibroids. Fibroids may cause problems during pregnancy and labor, and they increase the chance of needing a cesarean delivery.
If fibroids are large, there may also be weight gain and swelling in the lower abdomen.
It remains unclear exactly what causes fibroids. Their development may be linked with the person’s estrogen levels.
Low estrogen levels are associated with the shrinkage of fibroids. This can occur during and after menopause. It can also occur when taking certain medications, such as gonadotropin-releasing hormone (GnRH) agonists or antagonists.
Genetic factors may also affect the development of fibroids. For example, having a close relative with fibroids is associated with an increased risk of developing them oneself.
There is also evidence to suggest that red meat, alcohol, and caffeine are associated with an increased risk of fibroids. An increased intake of fruit and vegetables may be linked with a reduced risk.
Overweight and obesity are associated with an increased risk of fibroids.
Childbearing is associated with a lower risk of developing fibroids. The risk reduces each time the person gives birth.
The following diagnostic tests can help a doctor detect fibroids and rule out other conditions:
- Ultrasound scans: A doctor can create ultrasound images by scanning over the abdomen or by inserting a small ultrasound probe into the vagina. Both approaches may be necessary to detect fibroids.
- MRI scans: An MRI scan can determine the size and number of fibroids.
- Hysteroscopy: During a hysteroscopy, a doctor will use a small device with a camera attached to the end to examine the inside of the uterus. They will insert the device through the vagina and into the uterus via the cervix. If necessary, they may also take a tissue sample, known as a biopsy, to look for cancer cells.
- Laparoscopy: A doctor might also perform a laparoscopy. They will insert a small, lighted tube into a small incision in the abdomen to examine the outside of the uterus and its surrounding structures. If necessary, they might also take a biopsy.
As fibroids often do not cause symptoms, a person may not know that they have fibroids until they undergo a routine pelvic examination.
Most fibroids do not cause symptoms and do not require treatment. In fact, they often shrink or disappear after menopause.
If fibroids are causing uncomfortable symptoms, however, various medical treatments can help.
A doctor may recommend different treatments depending on the symptoms, the severity of the symptoms, and the location of the fibroids.
The first line of treatment for fibroids is medication. The following sections will discuss some possible medications for fibroids in more detail.
A drug called a GnRH agonist causes the body to produce less estrogen and progesterone. This shrinks fibroids. GnRH agonists stop the menstrual cycle without affecting fertility after the end of treatment.
GnRH agonists can cause menopause-like symptoms, including hot flashes, a tendency to sweat more, vaginal dryness, and, in some cases, a higher risk of osteoporosis.
GnRH agonists are for short-term use only. A doctor may give a person these medications before surgery to shrink fibroids.
A newer therapy using GnRH antagonists is another possible treatment option.
Nonsteroidal anti-inflammatory drugs
Nonsteroidal anti-inflammatory drugs, such as ibuprofen, can reduce fibroid pain, but they do not reduce bleeding.
Hormonal birth control
People can also use a progesterone intrauterine device, such as Mirena, or progesterone-like injections, such as Depo-Provera.
Severe fibroids may not respond to more conservative treatment options. In these cases, surgery may be the best treatment option.
The doctor may consider the following procedures:
A hysterectomy is the partial or total removal of the uterus. This method can treat extremely large fibroids or excessive bleeding. Total hysterectomy can prevent the return of fibroids.
If a surgeon also removes the ovaries and fallopian tubes, side effects can include reduced libido and early menopause.
This is the removal of fibroids from the muscular wall of the uterus. It can help people who still want to have children.
Those with large fibroids or fibroids located in particular parts of the uterus may not benefit from this type of surgery.
Clinicians can perform myomectomy through hysteroscopy or laparoscopy.
Removing the uterine lining may help if fibroids are near the inner surface of the uterus. Endometrial ablation may be an effective alternative to a hysterectomy for some people with fibroids.
Uterine fibroid embolization
Cutting off the blood supply to the area shrinks the fibroid. Guided by fluoroscopic X-ray imaging, the doctor will inject a chemical through a catheter into the arteries supplying blood to any fibroids.
This procedure reduces or removes symptoms in up to 90% of people with fibroids, but it is not suitable during pregnancy or for those who may want to have children.
That said, the resolution of symptoms is highly variable depending on the location and size of fibroids. This is not an appropriate treatment method for all types of fibroid.
Maintaining a moderate weight by getting regular exercise and eating a healthful diet may help moderate estrogen levels, which may help reduce fibroids.
Fibroids do not normally result in complications, but they can sometimes occur.
Consistently heavy periods may affect a person’s quality of life. Significant blood loss may also lead to anemia.
Large fibroids can lead to swelling and discomfort in the lower abdomen or cause constipation or painful bowel movements.
Some people might develop urinary tract infections as a result of fibroids.
Some people may also experience pregnancy problems. Preterm birth, labor problems, and pregnancy loss may occur, as estrogen levels rise significantly during pregnancy.
There is not enough evidence to conclude that myomas reduce the likelihood of becoming pregnant with or without fertility treatment.
That said, there is fair evidence to suggest that hysteroscopic myomectomy for submucosal fibroids improves clinical pregnancy rates.
Uterine fibroids are almost always benign. Cancerous fibroids, known as leiomyosarcomas, are rare. According to some sources, they occur in fewer than 1 in 1,000 cases.