What are fibroids? A plain explanation

Fibroids are growths made of muscle and tissue that develop in the wall of the uterus or on its surface. Their medical name is leiomyoma [1]. They can grow within the muscular wall, beneath the inner lining, beneath the outer surface, or on a stalk attached to the uterus [1]. In an ultrasound-screened cohort, the estimated cumulative incidence by age 50 was over 80% for Black women and nearly 70% for white women [3]. After menopause, the Office on Women’s Health says fibroids either stop growing or get smaller [2].

What exactly is a fibroid?

A uterine fibroid is a muscle-and-tissue growth that forms in the uterine wall or along the outside of the uterus [1]. It is also called a leiomyoma [1].

Fibroids are described by where they sit:

• Intramural fibroids are within the muscular wall of the uterus. Cleveland Clinic identifies these as the most common type [1].
• Submucosal fibroids grow beneath the uterus’s inner lining [1].
• Subserosal fibroids grow beneath the lining on the outer surface and can become quite large [1].
• Pedunculated fibroids connect to the uterus by a stalk or stem [1].

Tests used to find or assess fibroids include ultrasonography, magnetic resonance imaging, computed tomography, hysteroscopy, hysterosalpingography, sonohysterography, and laparoscopy [1].

How common are fibroids?

The Office on Women’s Health puts the share of women who develop fibroids by age 50 at 20% to 80% [2]. Cleveland Clinic reports that approximately 40% to 80% of people with a uterus have fibroids, most often between ages 30 and 50 [1]. These figures come from different sources and should remain in their original form.

The ultrasound cohort included 1,364 women. Its estimated cumulative incidence of uterine fibroid tumors by age 50 was over 80% for Black women and nearly 70% for white women [3]. The difference between the age-specific cumulative incidence curves was highly significant, with an odds ratio of 2.9 and a 95% confidence interval of 2.5 to 3.4 [3].

Among premenopausal women in that cohort, 35% had a previous diagnosis of fibroid tumors. Among premenopausal women with no previous diagnosis, 51% had ultrasound evidence of fibroid tumors [3].

Who develops fibroids, and when?

The ultrasound research found that fibroid tumors develop in Black women at earlier ages than in white women. It also reported that most Black and white women in the United States develop fibroids before menopause [3].

Another review reports that African American women have fibroids diagnosed at earlier ages, are more likely to be symptomatic, and have greater fibroid size and growth rates [4]. The Office on Women’s Health reports that fibroids are more likely in African American women than in white women [2].

Cleveland Clinic lists family history, not having children, early onset of menstruation, and later age at menopause as risk factors [1].

Approximately 42 per 1,000 women are hospitalized annually because of fibroids [4]. African American women have higher rates of hospitalization, myomectomies, and hysterectomies than white women, with relative risks of 3.5, 6.8, and 2.4, respectively [4].

What symptoms can fibroids cause?

Cleveland Clinic lists excessive or painful bleeding during periods, bleeding between periods, fullness or bloating in the lower abdomen, frequent urination, pain during sex, low back pain, constipation or rectal pressure, chronic vaginal discharge, inability to empty the bladder completely, and increased abdominal distention [1].

The published symptom list does not identify which fibroid type causes each symptom [1]. Imaging is used to find or assess fibroids [1].

Heavy menstrual bleeding can include periods lasting longer than seven days, soaking through a pad or tampon every hour for several hours, wearing more than one pad at a time, changing pads during the night, and passing blood clots the size of a quarter or larger several times a day [5].

Possible causes of heavy menstrual bleeding include hormone imbalance, polyps, fibroids, adenomyosis, infections, pregnancy complications, bleeding disorders such as von Willebrand disease, liver or kidney disease, cancers, and some medications, including blood thinners [5].

Heavy bleeding can lead to tiredness or shortness of breath from blood loss, which may lead to anemia [5]. Iron-deficiency anemia is usually caused by bleeding, and blood loss from periods is a listed cause [7]. Its listed symptoms include fatigue, headaches, irritability, muscle cramps, pale skin, pica, shortness of breath, sore tongue, spoon-shaped nails, and a fast heart rate [7].

When is bleeding too heavy to wait?

Cleveland Clinic says that soaking at least two pads or tampons per hour and continuing across two to three consecutive hours calls for prompt professional evaluation [5]. It also lists bleeding that soaks a pad or tampon every hour for several hours as a sign of heavy menstrual bleeding [5].

Write down how often you change pads or tampons. Record whether you need more than one at a time, change them during the night, or pass clots the size of a quarter or larger several times a day [5].

If heavy bleeding is followed by tiredness or shortness of breath, ask whether blood work is needed [5]. Blood work used for iron-deficiency anemia includes ferritin and total iron-binding capacity [7].

How are fibroids found?

For heavy menstrual bleeding, the listed tests include pelvic ultrasound, blood tests, transvaginal ultrasound, MRI, Pap test, cervical culture, endometrial biopsy, sonohysterogram, and hysteroscopy [5]. At your appointment, ask which test you had, what the report says, and whether another test is needed.

Are fibroids cancer?

Fibroids are nearly always benign, according to the Office on Women’s Health [2]. Cleveland Clinic says it is extremely rare for a fibroid to change into a cancerous tumor and reports that 1 out of 350 people with fibroids will develop cancer [1]. The Office on Women’s Health gives a different estimate, putting the chance of a cancerous fibroid below 1 in 1,000 [2].

Those published estimates differ. The sources do not provide a rule for interpreting an individual imaging report. Ask what your report says and whether more assessment is needed.

What changes during perimenopause?

Perimenopause is the transitional period before menopause, when estrogen levels start to decrease [6]. It usually starts in the mid-40s, but it may begin as early as the mid-30s or as late as the mid-50s [6]. It runs about four years on average, with an upper end of eight years [6].

During perimenopause, menstrual cycles can become longer or shorter than usual, and bleeding can become heavier or lighter than normal [6]. Listed symptoms include irregular periods, heavier or lighter periods, mood changes including irritability and depression, low libido, hot flashes, night sweats, vaginal dryness with discomfort during sex, urinary urgency, and trouble sleeping [6].

Cleveland Clinic says to contact a provider about bleeding that is very heavy, soaks a pad every one to two hours, lasts longer than usual, occurs between periods, follows sex, or happens when periods come less than 21 days apart [6].

Menopause is reached after 12 months in a row without a menstrual period [6]. The Office on Women’s Health reports that fibroids either stop growing or become smaller after menopause [2].

Do fibroids always need treatment?

No. Cleveland Clinic says small fibroids often need no treatment at all [1].

Published treatment lists include medication and procedures for fibroids and heavy menstrual bleeding [1][5]. The medical-management review says no available treatment option permanently stops fibroid tumor growth, and symptoms return after effective therapy ends [4]. Medication manages symptoms. GnRH agonists and antagonists can reduce fibroid size while treatment continues, but medication does not remove fibroids [4].

What should you ask about the scan and the next step?

Use this checklist at the appointment. Write the answers in the right-hand column.

What to do next

1. Bring the checklist to your appointment.
2. Record whether you have bleeding between periods, bleeding after sex, pelvic pressure, frequent urination, pain during sex, low back pain, constipation, or trouble emptying your bladder [1][5].
3. Record how long your periods last and whether you soak a pad or tampon every hour for several hours [5].
4. Bring your imaging report and ask what it says about the size, number, and location of each fibroid.
5. Open with: “I was told I have fibroids, and I need to understand what the report says about their size, number, location, and whether anything needs to happen now.”
6. Ask whether blood work is needed if you have heavy bleeding, tiredness, or shortness of breath [5][7].
7. If you soak at least two pads or tampons per hour across two to three consecutive hours, seek prompt professional evaluation [5].

Related on Ruby: uterine fibroid symptoms and fibroids treatment.

Sources

1. Cleveland Clinic, Uterine fibroids. https://my.clevelandclinic.org/health/diseases/9130-uterine-fibroids
2. Office on Women’s Health, Uterine fibroids. https://womenshealth.gov/a-z-topics/uterine-fibroids
3. Baird 2003, High cumulative incidence of uterine leiomyoma in black and white women, PubMed. https://pubmed.ncbi.nlm.nih.gov/12548202/
4. Eltoukhi 2013, The health disparities of uterine fibroids for African American women, PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC3874080/
5. Cleveland Clinic, Menorrhagia (heavy menstrual bleeding). https://my.clevelandclinic.org/health/diseases/17734-menorrhagia-heavy-menstrual-bleeding
6. Cleveland Clinic, Perimenopause. https://my.clevelandclinic.org/health/diseases/21608-perimenopause
7. Cleveland Clinic, Iron-deficiency anemia. https://my.clevelandclinic.org/health/diseases/22824-iron-deficiency-anemia