What Is a Myoma? Causes, Symptoms, and Treatment

A myoma is a benign tumor made of smooth muscle cells, and the term almost always refers to a uterine fibroid, the single most common pelvic tumor in women of reproductive age. By age 50, roughly 70 percent of women will have at least one, though many never know it because fibroids frequently cause no symptoms at all.¹ The medical name is leiomyoma, but “myoma” and “fibroid” are used interchangeably in clinics and imaging reports. When symptoms do appear, they range from heavy bleeding and pelvic pressure to fertility problems, and the treatment options now span everything from medication to focused ultrasound to surgery.

What Exactly Is a Myoma Made Of

A myoma grows from the smooth muscle layer of the uterus, called the myometrium. Each fibroid starts as a single cell that begins multiplying out of step with its neighbors, gradually forming a firm, rubbery mass surrounded by a thin capsule. Fibroids can be as small as a seed or as large as a melon, and a single uterus can contain one or dozens. They are overwhelmingly benign. The risk of a fibroid actually being a cancerous look-alike (leiomyosarcoma) is very low, a point covered in more detail later in this article.

Doctors classify fibroids by where they sit in the uterine wall. The International Federation of Gynecology and Obstetrics (FIGO) created a standardized numbering system that describes a fibroid’s relationship to the inner lining, the muscle layer, and the outer surface of the uterus.² The FIGO system recognizes nine types, ranging from fibroids that bulge entirely into the uterine cavity (submucosal) to those that project outward from the uterus (subserosal), with several intramural categories in between.³ This classification matters because a fibroid’s location drives its symptoms and determines which treatments are on the table.

Why Fibroids Develop

No single cause explains fibroids, but hormones sit at the center of the story. For decades, estrogen was blamed as the primary growth driver. More recent work has shifted attention to progesterone, which interacts with receptors on fibroid cells to activate pathways that promote tumor growth and survival.⁴ Both hormones play a role: fibroids are hormone-dependent tumors driven by progesterone and estradiol together.⁵ This hormonal dependence explains why fibroids virtually never appear before puberty and tend to shrink after menopause, when hormone levels drop.

Genetics plays a surprisingly large role. Nearly 70 percent of fibroids carry mutations in a gene called MED12.⁶ Researchers have identified at least two separate pathways that lead to fibroid formation: one driven by MED12 mutations and another driven by rearrangements of a different set of genes known as HMGA proteins. These two pathways appear to be mutually exclusive, meaning a given fibroid tends to follow one route or the other.⁷ Beyond these somatic mutations (which arise in individual cells during a person’s life), having a family history of fibroids also raises your risk, pointing to inherited genetic susceptibility on top of the mutations that kick off individual tumors.

Who Gets Fibroids and What Raises the Risk

Age is the strongest risk factor. The incidence of fibroids climbs steadily through the reproductive years and peaks around age 50.⁸ Ethnicity matters too. Black women develop fibroids earlier, grow more of them, and tend to have larger and more symptomatic tumors than white women.¹ The reasons for this disparity appear to be a combination of genetic differences, differential exposure to environmental risk factors, and unequal access to healthcare.

Other well-documented risk factors include being overweight or obese, having a positive family history, and early onset of menstruation.⁹ Obesity raises risk partly because fat tissue produces estrogen through a process called aromatization, adding to the hormonal fuel that fibroids need to grow.¹⁰

Common Symptoms and When Fibroids Stay Silent

Many fibroids produce no symptoms whatsoever and are discovered incidentally on an ultrasound done for another reason. When symptoms do develop, the most common complaint is heavy menstrual bleeding, sometimes severe enough to cause anemia. The bleeding seems to result from changes in the blood vessel architecture within and around fibroids. Abnormal vascular networks, venous congestion caused by fibroids blocking normal blood flow, and the local action of growth factors that dilate blood vessels all contribute.¹¹

Beyond bleeding, symptoms depend heavily on a fibroid’s size and location:

Pelvic pressure or pain: Large fibroids can press on the bladder (causing frequent urination), the rectum (causing constipation), or nearby nerves.
Abdominal bloating: A uterus enlarged by fibroids can visibly distend the lower abdomen, sometimes mistaken for weight gain.
Pain during periods or intercourse: Submucosal fibroids, in particular, can cause cramping that goes well beyond typical menstrual discomfort.
Fertility problems: Fibroids near or distorting the uterine cavity can interfere with embryo implantation or increase miscarriage risk, discussed further below.

Submucosal fibroids (those that bulge into the uterine cavity) tend to cause the worst bleeding even when small, while subserosal fibroids (those growing outward) can reach a considerable size before producing any symptoms at all. This is why a fibroid’s FIGO type matters as much as its raw size.

How Fibroids Are Diagnosed

A standard pelvic ultrasound is usually the first-line tool and catches most fibroids. However, MRI provides a more detailed picture. In a comparison of the two methods before myomectomy (surgical fibroid removal), MRI detected roughly twice as many fibroids as ultrasound, though both underestimated what surgeons actually found on the operating table.¹² MRI is also better at spotting coexisting conditions like adenomyosis and can characterize fibroids more precisely, identifying features like whether a fibroid protrudes into the cavity or has undergone degeneration.¹³ For routine monitoring, ultrasound is typically sufficient, but MRI becomes more important when a procedure like uterine artery embolization or surgery is being planned.

Medical Treatment Options

Not every fibroid needs treatment. If you have no symptoms and the fibroid is not growing rapidly, watchful waiting is a perfectly reasonable strategy. When treatment is needed, several drug classes can help manage symptoms or temporarily shrink fibroids.

GnRH antagonists (such as relugolix, linzagolix, and elagolix, often combined with low-dose hormones to limit side effects) are among the newer medical options. A meta-analysis of randomized trials found that women on GnRH antagonists were about five times more likely to achieve control of heavy bleeding compared to those on placebo, and fibroids shrank by a moderate amount.¹⁴ These drugs work by dialing down the body’s production of estrogen and progesterone. They are taken as daily pills, a significant convenience compared to older GnRH agonists that required injections and caused more severe menopausal side effects.

For heavy bleeding specifically, tranexamic acid (a non-hormonal medication that helps blood clot) can reduce menstrual blood loss and is sometimes used around surgery to cut down on bleeding during myomectomy.¹⁵ Hormonal IUDs, birth control pills, and progestin-only options can also help manage bleeding symptoms, although they do not shrink the fibroids themselves.

Procedures That Avoid Major Surgery

Between medication and full surgery, there is a growing middle ground of minimally invasive options. Two of the most studied are uterine artery embolization (UAE) and MRI-guided high-intensity focused ultrasound (MRgHIFU). UAE involves a radiologist threading a catheter into the arteries feeding the fibroid and injecting tiny particles that block blood flow, causing the fibroid to shrink. MRgHIFU uses focused sound waves to heat and destroy fibroid tissue without any incision at all.

A systematic review comparing the two found that UAE achieved greater fibroid shrinkage at six, twelve, and twenty-four months. However, UAE also came with more side effects, particularly pain, nausea, and vomiting. The review could not definitively declare one approach superior because of differences in the patients and fibroids treated in each group.¹⁶ Both are generally appropriate for women who want to avoid surgery, though neither is recommended if you are actively trying to conceive, since the long-term effects on fertility are not fully established.

When Surgery Makes Sense

For a long time, hysterectomy (removal of the uterus) was essentially the only surgical option. It was the gold standard for fibroid treatment until well into the twentieth century. Myomectomy, which removes fibroids while preserving the uterus, only gained mainstream acceptance after a landmark publication in 1925 describing over 200 successful procedures.¹⁷ Today both procedures are widely available, performed through open abdominal, laparoscopic, robotic, or hysteroscopic approaches depending on the size, number, and location of fibroids.

Hysterectomy remains highly effective and is associated with a high rate of patient satisfaction, relieving menstrual problems in virtually all women.¹⁸ A comparison of quality of life one year after surgery found that both hysterectomy and myomectomy improved quality of life and reduced symptom severity. When performed through minimally invasive approaches, hysterectomy patients reported somewhat higher quality-of-life scores than myomectomy patients. When both were done through open abdominal surgery, the difference was minimal.¹⁹

Myomectomy is the obvious choice for anyone who wants to preserve fertility. One downside: fibroids can grow back after myomectomy, and the procedure itself can cause adhesions (scar tissue) in the pelvic cavity, which may themselves affect fertility.¹⁸ The choice between the two surgeries typically comes down to whether you want future pregnancies, how severely you are affected, and the characteristics of the fibroids themselves.

Fibroids and Fertility

The relationship between fibroids and getting pregnant is one of the most common concerns women raise with their doctors. The short answer is that location matters far more than size or even number. Fibroids in the submucosal layer, the ones that push into the uterine cavity, can physically interfere with embryo implantation and raise the risk of miscarriage. Removing them hysteroscopically improves outcomes for both natural conception and assisted reproduction.²⁰ Fibroids that grow purely outward from the uterus (subserosal) do not appear to affect fertility at all.

Fibroids are estimated to be associated with infertility in roughly 5 to 10 percent of affected women, and they are the sole identifiable cause in about 2 to 3 percent.²⁰ There is also growing evidence that intramural fibroids (the type embedded entirely within the muscle wall) may reduce success rates in IVF, even if they do not obviously distort the cavity.²¹

During pregnancy, fibroids raise the risk of complications including miscarriage. A multicenter study found that a single fibroid did not significantly increase the odds of late miscarriage, but having multiple fibroids roughly doubled the odds. When researchers looked specifically at submucosal fibroids, those increased the odds of late miscarriage by nearly five times.²² Fibroids in other locations did not show the same statistical association.

Diet, Vitamin D, and Other Lifestyle Factors

A question that comes up frequently is whether anything you eat or do can prevent fibroids or slow their growth. The evidence here is still evolving but consistently points in a few directions. Diets high in saturated fat, particularly from red meat and full-fat dairy, may raise circulating estrogen levels and contribute to fibroid development. In contrast, diets rich in fiber, fruits, and vegetables appear to lower risk.¹⁰

Vitamin D is a particularly interesting area. Women with sufficient vitamin D levels had roughly a third lower odds of having fibroids compared to those with insufficient levels, and the association held for both Black and white women. Getting at least an hour of daily sun exposure (when weather permits) was also linked to reduced odds.²³ A small randomized trial went further, finding that vitamin D supplementation appeared to prevent fibroid growth over the study period: fibroids in the supplement group shrank slightly, while those in the control group grew by about 6 millimeters on average.²⁴ That is promising but still preliminary. Vitamin D is not a substitute for medical treatment, though maintaining adequate levels is unlikely to hurt and may help.

Can a Fibroid Turn Into Cancer

This is one of the most anxiety-producing questions for people newly diagnosed with fibroids, and the reassuring answer is that fibroids essentially do not transform into cancer. Leiomyosarcoma, the malignant smooth-muscle tumor of the uterus, is a separate entity that arises independently. It is rare and tends to occur in postmenopausal women.

Distinguishing the two is mainly a concern for clinicians, and imaging helps. On MRI, a suspicious lesion often shows a pattern called coagulative necrosis, which appears as a central area with no blood flow, surrounded by an abrupt boundary. This looks different from the scattered, patchy degeneration commonly seen in ordinary fibroids.²⁵ Histological examination reinforces the distinction: leiomyosarcomas with a poor prognosis tend to be composed of uniform spindle cells and completely lack progesterone and estrogen receptors, while fibroids and low-risk smooth-muscle tumors retain those receptors.²⁶ In practical terms, if your doctor sees features of ordinary degeneration on imaging, cancer is exceedingly unlikely.

Fibroids Outside the Uterus

When people hear “myoma,” they almost always mean uterine fibroids. But leiomyomas can technically arise anywhere smooth muscle exists. Cutaneous leiomyomas, for instance, are rare tumors found on the skin, often on the arms, legs, or trunk.²⁷ Even more unusual is a condition called benign metastasizing leiomyoma, where smooth-muscle tumors turn up in distant sites like the lungs or even the heart, sometimes years after a hysterectomy for uterine fibroids. Cardiac benign metastasizing leiomyoma, while rare, can lead to serious complications including heart failure.²⁸

Whether these distant tumors are truly “metastases” from a uterine fibroid or independent growths arising in multiple locations is an open question. A case report documented a woman who developed smooth-muscle tumors in the chest, neck, abdominal scar, and intestinal tissue years after a hysterectomy. The distribution and prolonged timeline led the authors to suggest that multifocal origin (separate tumors arising independently) may explain some of these cases better than the idea of a benign tumor spreading through the bloodstream.²⁹ These scenarios are medical curiosities and not something most fibroid patients need to worry about.

Racial Disparities in Fibroid Care

Beyond the biological differences in fibroid prevalence, there are well-documented inequities in how fibroids are treated. A systematic review found that Black women with fibroids experience worse clinical and surgical outcomes than white women, linked to differential exposure to suspected risk factors, less access to skilled surgeons, and bias within the healthcare system.³⁰

These disparities show up in concrete treatment patterns. A study of veterans using VA healthcare found that Black veterans were less likely to receive any fibroid treatment compared to white veterans, with the gap widest among women who also had anemia.³¹ Separately, a large analysis found that after controlling for age, insurance type, and year of surgery, Black patients had a higher probability of undergoing the most invasive treatment. Income and educational attainment also predicted treatment invasiveness, with lower-income and less-educated patients more likely to receive aggressive procedures.³² These patterns suggest that disparities are not purely biological. Structural factors like insurance coverage, geographic access to specialists, and implicit provider bias all shape outcomes.

The Emotional and Quality-of-Life Toll

Fibroids are sometimes talked about as if they are merely a physical nuisance, but research consistently shows a substantial impact on quality of life and mental health. Unpredictable heavy bleeding can restrict social activities, cause embarrassment, and lead to chronic fatigue from iron-deficiency anemia. Pelvic pain and pressure interfere with exercise, work, and sex. A systematic review of fibroid treatments found that across radiologic, medical, and surgical interventions, validated quality-of-life questionnaires documented meaningful impairment before treatment, and meaningful improvement afterward.³³ If you have been dismissing your symptoms as something you just have to live with, that evidence suggests treatment can make a real difference in daily life, not just in managing a tumor on an imaging scan.

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