Uterine lesions are abnormal growths or tissue changes within the uterus, and they are remarkably common. The term covers everything from fibroids, which affect a majority of women by midlife, to endometrial polyps, adenomyosis, hyperplasia, and the rare but serious uterine sarcoma. Most uterine lesions are benign, but they vary widely in how much trouble they cause, and the symptoms often overlap enough that pinning down what you’re dealing with takes more than a single ultrasound. What matters most is where the lesion sits, what type of tissue it involves, and whether it has features that warrant closer monitoring.
The Main Types and What Sets Them Apart
Fibroids, also called leiomyomas, are the most familiar uterine lesion. They are firm, round masses of smooth muscle and connective tissue that grow in and around the uterine wall. Their location determines much of their clinical behavior. Submucosal fibroids bulge into the uterine cavity and tend to cause the heaviest bleeding. Intramural fibroids sit within the muscular wall. Subserosal fibroids project outward from the uterus and often produce pressure symptoms rather than heavy periods. A single uterus can harbor all three types simultaneously.
Endometrial polyps are softer, finger-like projections of endometrial tissue that extend into the uterine cavity. They share some symptoms with submucosal fibroids, particularly irregular bleeding, but they are structurally different and generally smaller. Adenomyosis is a condition in which endometrial-like tissue invades the muscular wall of the uterus itself, creating a diffusely enlarged, boggy uterus rather than a discrete mass. The pain it causes, especially during menstruation, tends to be more severe and cramping than typical fibroid discomfort.
Endometrial hyperplasia is an overgrowth of the uterine lining rather than a mass. It matters because it can be a precursor to endometrial cancer, particularly when the overgrown cells show atypia. A long-term follow-up study found that hyperplasia without atypia carried a cumulative progression risk to cancer of under 5% over roughly 20 years, while atypical hyperplasia reached about 28% over the same period.1PubMed Central. Absolute risk of endometrial carcinoma during 20-year follow-up among women with endometrial hyperplasia A meta-analysis found the annual incidence of progression to cancer was around 8% for atypical hyperplasia.2PLOS ONE. Concurrent and future risk of endometrial cancer in women with endometrial hyperplasia: A systematic review and meta-analysis That distinction between atypical and non-atypical hyperplasia drives treatment decisions more than almost any other single factor.
Uterine sarcomas are the rarest and most concerning type. These are cancerous tumors arising from the muscle or connective tissue of the uterus. The challenge is that they can look a lot like large fibroids on imaging. MRI helps distinguish the two: benign fibroids tend to appear dark on certain MRI sequences and have well-defined borders, while sarcomas tend to be larger, irregularly outlined, and show intermediate signal intensity along with features like hemorrhage and tissue invasion.3PubMed Central. Differentiating uterine sarcoma from leiomyoma: BET1T2ER check! Advanced diffusion-weighted MRI can further improve confidence in telling the two apart.4PubMed. Diagnostic Algorithm to Differentiate Benign Atypical Leiomyomas from Malignant Uterine Sarcomas with Diffusion-weighted MRI
How Symptoms Differ by Type and Location
Heavy menstrual bleeding is the most common complaint across several types of uterine lesions, but the mechanism differs. Fibroids disrupt the normal contraction of the uterine muscle and alter the local production of blood vessel-constricting substances in the endometrium. They also promote new blood vessel growth and reduce clotting factors in the area, all of which contribute to heavier periods.5PubMed Central. Literature Review on the Role of Uterine Fibroids in Endometrial Function Submucosal fibroids are the worst offenders. Women with submucosal fibroids had significantly lower hemoglobin levels and were roughly 46% more likely to be anemic compared with women without them.6PubMed Central. Submucosal fibroids and the relation to heavy menstrual bleeding and anemia
Adenomyosis produces heavy bleeding too, but it also causes distinctively painful periods. The pain comes from inflammation, abnormal nerve growth, increased blood vessel formation, and disordered contractions within the uterine wall where the endometrial tissue has invaded.7PubMed Central. Adenomyosis: Mechanisms and Pathogenesis Women with adenomyosis often describe a deep, achy cramping that feels different from standard menstrual cramps and may persist beyond the period itself.
Pressure symptoms are more typical of larger fibroids, particularly intramural and subserosal ones. A bulky uterus can press on the bladder, causing frequent urination, or on the rectum, causing constipation. Some women notice a visible lower abdominal bulge. Endometrial polyps and hyperplasia, by contrast, tend to announce themselves primarily through irregular or unexpected bleeding, especially between periods or after menopause, rather than through pressure or pain.
Fibroids and Fertility
Whether a fibroid affects your ability to conceive depends almost entirely on where it is. Submucosal fibroids have the clearest link to infertility and pregnancy loss. They distort the uterine cavity, potentially interfering with embryo implantation, and removing them has been shown to improve pregnancy rates. Intramural fibroids appear to reduce fertility as well, though the evidence on whether removing them helps is less clear-cut. Subserosal fibroids, sitting on the outer surface, do not seem to affect fertility at all, and removing them does not improve outcomes.8PubMed Central. Uterine Fibroids and Infertility
A prospective study reinforced this pattern, finding that women with submucosal and large intramural fibroids had significantly lower conception rates, longer times to conception, and higher rates of miscarriage and obstetric complications. Fibroids measuring 5 cm or larger were associated with increased risk of preterm labor and cesarean delivery.9International Journal of Current Pharmaceutical Review and Research. Impact of Uterine Fibroids on Fertility and Pregnancy Outcomes: A Prospective Observational Study Size and location together determine the practical impact. A small subserosal fibroid is often an incidental finding that requires no intervention, while even a modest submucosal fibroid can be the explanation for unexplained infertility.
How Uterine Lesions Are Diagnosed
Transvaginal ultrasound is the usual first step. It is inexpensive, widely available, and good enough to identify most fibroids and many polyps. But its sensitivity has limits, particularly for smaller intracavitary lesions. For detecting endometrial polyps, a meta-analysis found that standard transvaginal ultrasound caught only about 55% of cases, while saline infusion sonohysterography, where sterile saline is instilled into the uterus to separate its walls during imaging, detected about 92%.10PubMed. Two-dimensional transvaginal sonography vs saline contrast sonohysterography for diagnosing endometrial polyps: systematic review and meta-analysis For submucosal fibroids, one study found saline sonohysterography reached 100% sensitivity, compared with about 62% for standard ultrasound.11PubMed Central. Comparison of transvaginal sonography and saline contrast sonohysterography in women with abnormal uterine bleeding: correlation with hysteroscopy and histopathology
When the full picture of fibroids matters, such as before a complex surgery or when a sarcoma needs to be ruled out, MRI is considered the best imaging tool. It excels at mapping the number, size, and exact location of fibroids as well as their relationship to surrounding structures.12PubMed Central. Role of MRI and FIGO Staging in Evaluation of Fibroids – A Pictorial Review
For lesions that may be hyperplasia or cancer, a tissue sample is essential. Hysteroscopically directed biopsy, where a thin camera is inserted into the uterus and tissue is taken under direct visualization, has the highest diagnostic accuracy, with a sensitivity of about 91% for detecting hyperplasia or carcinoma. Dilation and curettage caught about 82%, while the office-based Pipelle suction biopsy, which is by far the simplest to perform, detected about 72%.13PubMed Central. Diagnostic Efficiency of Endometrial Sampling Methods and Risk Factors for Endometrial Carcinoma and Precursor Lesions in Premenopausal Women Hysteroscopy also allows the doctor to see the cavity directly, which adds diagnostic value for polyps and submucosal fibroids that imaging may have characterized ambiguously.14Fertility and Sterility. A prospective comparison of transvaginal ultrasound, saline infusion sonohysterography, and diagnostic hysteroscopy in the evaluation of endometrial pathology
Medical and Hormonal Management
Not every uterine lesion needs surgery. For fibroids, the newest class of oral medications, GnRH antagonists taken as a daily pill with a small dose of add-back hormone, has changed the landscape. A meta-analysis found that these drugs achieved clinically meaningful bleeding control in roughly five times as many women as placebo, and reduced fibroid volume by an average of about 27%.15PubMed Central. Efficacy of GnRH antagonists in the treatment of uterine fibroids: a meta-analysis The add-back hormone component is important because it preserves bone density, a concern with older GnRH agonist injections that induced a temporary menopause-like state. Registration trial data shows these combination therapies maintain bone density for up to two years.16PubMed Central. Use of oral GnRH antagonists combined therapy in the management of symptomatic uterine fibroids
Selective progesterone receptor modulators are another option. A Cochrane review found that compared to placebo, these drugs improved fibroid symptom severity and quality of life, reduced menstrual blood loss, and induced amenorrhea in a high proportion of women. A three-month course did not cause harmful changes to the endometrium, though a characteristic benign endometrial pattern is commonly observed and pathologists need to be aware of it.17PubMed Central. Selective progesterone receptor modulators for uterine fibroids
For adenomyosis, the levonorgestrel-releasing intrauterine device (hormonal IUD) has strong evidence behind it. A systematic review and meta-analysis of prospective studies found it effectively reduced symptom severity, uterine volume, and endometrial thickness.18PubMed. The role of levonorgestrel intra-uterine system in the management of adenomyosis: A systematic review and meta-analysis of prospective studies The catch is that adenomyosis comes in subtypes, and for the type involving extensive outer wall disease, the IUD has higher failure and expulsion rates.19PubMed Central. Efficacy of the levonorgestrel-releasing intrauterine device is associated with different subtypes of adenomyosis: a retrospective study This means the response to the hormonal IUD partly depends on which pattern of adenomyosis you have, which is something imaging can help clarify before treatment begins.
Interventional and Surgical Options
When medications are not enough or the lesion requires removal, the options range from minimally invasive procedures to full hysterectomy. Hysteroscopic resection, performed through the cervix with no abdominal incisions, is the standard for submucosal fibroids and endometrial polyps. For larger or multiple fibroids, myomectomy removes the growths while preserving the uterus, which matters for anyone who wants future pregnancies.
Uterine artery embolization (UAE) is a catheter-based procedure in which tiny particles are injected into the arteries feeding the uterus, cutting off blood supply to the lesion. It works for fibroids and adenomyosis alike. For adenomyosis specifically, a meta-analysis of over 1,000 patients found symptom improvement in about 83%.20PubMed. Uterine Artery Embolization for the Treatment of Adenomyosis: A Systematic Review and Meta-Analysis A long-term follow-up study found that 80% of women treated with UAE for adenomyosis still had durable results at an average of just over four years, though about 10% experienced symptom recurrence needing further treatment.21PubMed Central. Long‐term durability of uterine artery embolisation for treatment of symptomatic adenomyosis
High-intensity focused ultrasound (HIFU) is a newer, completely noninvasive approach that uses focused sound waves to heat and destroy fibroid tissue through the skin. One center reported an average fibroid volume reduction of 68% at six months and 75% at 12 months, with significant symptom improvement and a re-intervention rate of under 8%.22PubMed Central. High-intensity Focused Ultrasound for the Treatment of Fibroids: A Single-center Experience in Singapore An evidence review covering nearly 1,600 patients found that major complications occurred in only about 1.6% of cases, though long-term follow-up data remains limited.23PubMed Central. Magnetic Resonance-Guided High-Intensity Focused Ultrasound (MRgHIFU) Treatment of Symptomatic Uterine Fibroids: An Evidence-Based Analysis Portable systems are also making HIFU accessible in outpatient settings, which could broaden access considerably.24PubMed Central. Ablation of symptomatic uterine fibroids with the Mirabilis system for rapid noninvasive ultrasound-guided high-intensity focused ultrasound (HIFU): a prospective observational clinical study
Hysterectomy remains the only treatment that eliminates the possibility of fibroid recurrence. A study comparing outcomes found that quality of life and symptom severity improved across all modalities at one year, but hysterectomy produced the largest gains.25PubMed. Comparative effectiveness of hysterectomy versus myomectomy on one-year health-related quality of life in women with uterine fibroids A longer follow-up confirmed that uterus-sparing procedures, including myomectomy and UAE, also produced significant and lasting improvement, though there was a gradual trend toward some symptom return in the second and third years. The researchers noted that the hysterectomy advantage on quality-of-life scales may partly reflect how heavily those questionnaires weight bleeding, which by definition stops entirely after hysterectomy.26PubMed. Long-term health-related quality of life and symptom severity following hysterectomy, myomectomy, or uterine artery embolization for the treatment of symptomatic uterine fibroids
Racial and Ethnic Disparities in Fibroid Burden
Fibroids do not affect all populations equally, and the gap is not small. A large study in an integrated health care system found that Black patients had more than three times the age-standardized rate of fibroid diagnosis compared with White patients. Hispanic patients had about 37% higher rates. Among Asian and Pacific Islander subgroups, South Asian women had the highest incidence and were more likely to be diagnosed before age 35.27JAMA Network Open. Uterine Fibroid Diagnosis by Race and Ethnicity in an Integrated Health Care System
These are not just differences in who gets diagnosed. Black and Hispanic women tend to present with more severe disease. A study examining presurgical care found that both groups were significantly more likely to have hemoglobin levels under 10 g/dL before surgery and had higher rates of needing blood transfusions before their procedures.28PubMed. Racial Disparities in Medical Management of Uterine Fibroids Prior to Myomectomy or Hysterectomy A systematic review found that Black women disproportionately experience exposures across the lifespan that may contribute to higher incidence, earlier onset, and greater severity of fibroids, pointing to social, structural, and political factors rather than biology alone.29PubMed Central. Racial disparities in uterine fibroids and endometriosis: a systematic review and application of social, structural, and political context Understanding these disparities matters because treatment guidelines built on data from predominantly White study populations may not adequately serve the women who bear the greatest burden of the disease.
Environmental Chemicals and Fibroid Risk
An emerging body of research links endocrine-disrupting chemicals (EDCs) to the development of uterine fibroids and other uterine conditions. These are synthetic compounds found in plastics, personal care products, and industrial materials that can interfere with hormone signaling. Epidemiological studies have associated certain phthalates, particularly DEHP (a common plasticizer), with increased fibroid risk and severity.30PubMed Central. The role of endocrine-disrupting chemicals in uterine fibroid pathogenesis Bisphenol A, parabens, and per- and polyfluoroalkyl substances (PFAS) have also been implicated in the initiation or progression of fibroids, adenomyosis, and endometrial hyperplasia.31PubMed. The impact of endocrine-disrupting chemicals on uterine diseases
One particularly concerning finding is that the uterus may be most vulnerable during its development. Some perinatal EDC exposures have been shown to increase tumor formation later in life in both animal models and human studies, possibly through epigenetic changes that reprogram developing uterine tissue.32PubMed Central. Endocrine-disrupting chemicals and uterine fibroids This is still an evolving area of science, and no one can yet quantify what fraction of fibroid cases might be attributable to EDC exposure. But the consistency of the associations across multiple chemical classes and study designs is building a case that these exposures genuinely contribute to risk.
Genetics of Fibroids
At the molecular level, fibroids are not all the same. The most common driver mutation occurs in a gene called MED12, found in roughly 50 to 80% of fibroids. These mutations are gain-of-function, meaning they actively promote tumor growth rather than simply removing a brake. MED12-mutant fibroids tend to appear as multiple growths rather than solitary tumors and are more frequently observed in Black women.33PubMed. RISING STARS: Role of MED12 mutation in the pathogenesis of uterine fibroids At the cellular level, these mutations trigger signaling pathways that promote cell proliferation and excessive buildup of the tough, fibrous extracellular matrix that gives fibroids their characteristic firm texture.34Journal of Endometriosis and Uterine Disorders. MED12 somatic mutation promotes human uterine leiomyoma’s growth by trigging canonical Wnt4/β-catenin and TGF-β signaling through the EMT pathway
This molecular diversity has practical implications. Researchers are increasingly recognizing that fibroids driven by different mutations may respond differently to various treatments. While this has not yet translated into personalized therapy in routine clinical practice, it helps explain why two women with seemingly similar fibroids can have very different disease trajectories and treatment responses.
The Emotional and Financial Weight
The impact of uterine lesions extends well beyond the clinic. A qualitative study of women with symptomatic fibroids found that most experienced significant emotional responses including fear, anxiety, anger, and depression. Half felt helpless and believed they had no control over their condition. Many developed a negative self-image and expressed concerns about appearing less attractive, which created barriers to intimacy.35PubMed. Beyond the physical: a qualitative assessment of the burden of symptomatic uterine fibroids on women’s emotional and psychosocial health Survey data confirms that this distress reduces quality of life broadly, and it hits hardest among racial minorities and women in lower income brackets.36PubMed Central. Burden, Prevalence, and Treatment of Uterine Fibroids: A Survey of U.S. Women
The economic toll is staggering. A cost analysis estimated that the total annual economic burden of uterine fibroids in the United States ranges between roughly $14 billion and $42 billion when accounting for direct medical costs, lost productivity, and related expenses like assisted reproduction.37PubMed Central. The Annual Economic Burden of Uterine Fibroids in the United States (2010 Versus 2022): A Comparative Cost-Analysis For individual women, the costs accumulate through repeated imaging, medications, missed work, and eventually procedures that may carry their own recovery time and expense. All of this unfolds against a backdrop where many women report feeling that their symptoms were minimized or normalized for years before they received a diagnosis, adding frustration to an already heavy burden.