By Lisa Kuhns, PhD

Updated November 12, 2024

Uterine polyps, also known as endometrial polyps, are abnormal growths that project from the uterus lining, consisting of glands, stroma, and blood vessels.¹ These typically benign polyps vary in size from a few millimeters to several centimeters and can occupy a small area or fill the entire uterine cavity. Common in women aged 40 to 49, they can develop in both reproductive and postmenopausal stages.¹ Polyps can be classified as pedunculated when attached by a thin stalk or sessile with a broad base. While many women with uterine polyps are asymptomatic, these growths are implicated in 50% of cases of abnormal uterine bleeding and 35% of infertility cases.¹ Though often benign, uterine polyps may occasionally show hyperplastic or precancerous changes, necessitating careful evaluation and monitoring.²

The exact cause of uterine polyps remains uncertain, but several theories suggest that estrogen stimulation plays a significant role in their development. Polyps have been found to contain higher concentrations of estrogen receptors (ERs), specifically ER-alpha, and reduced progesterone receptors compared with normal endometrium, potentially causing abnormal growth and resistance to the natural shedding process seen in typical endometrial tissue. This hormonal imbalance may prevent polyp tissue from undergoing normal cyclical changes, contributing to its persistence.¹

In addition to hormonal influences, abnormalities in cellular apoptosis (programmed cell death) and proliferation appear to be involved. Markers such as B-cell lymphoma-2 (Bcl-2), which inhibits apoptosis, and Ki67, which indicates cellular proliferation, are elevated in polyps, especially during the proliferative phase of the menstrual cycle.¹ Increased Bcl-2 expression in polyps may lead to decreased cell death, allowing polyps to evade the normal shedding process. Furthermore, Ki67 expression is particularly high in the glandular epithelium of polyps, signifying increased cell growth, which is further elevated in women treated with tamoxifen, a drug with estrogen-like effects on the uterus that is commonly used in breast cancer treatment.¹

Genetic factors also contribute to polyp formation. Chromosomal rearrangements in stromal cells have been identified, with abnormalities in specific regions such as 6p21-22, 12q13-15, and 7q22. Additional genetic markers, including p63, aromatase P450, and steroidogenic factor-1, have been linked to polyp development, indicating a complex interaction between hormonal and genetic factors in polyp formation.¹

Inflammation is another potential factor in the pathogenesis of uterine polyps. Chronic localized inflammation may lead to the growth of new blood vessels and tissue expansion.¹ Elevated levels of cyclooxygenase-2 (COX-2) and increased activated mast cells are commonly found in polyps, suggesting an inflammatory response that promotes angiogenesis and tissue proliferation. Angiogenic factors like vascular endothelial growth factor (VEGF) and transforming growth factor beta-1 (TGF beta-1) are also elevated in polyps, contributing to increased blood vessel density and fibrotic tissue, characteristic of these growths.¹

These findings suggest that uterine polyps may arise from hormonal, genetic, and inflammatory factors. The interaction of these factors may lead to two distinct types of polyps: those driven by hormonal imbalances and those resulting from inflammation. This dual nature could explain variations in symptoms, recurrence rates, and potential implications for fertility and cancer risk.

Screening and diagnosis of uterine polyps typically involve a combination of clinical assessment, imaging techniques, and tissue sampling. The approach may vary based on the patient's symptoms, age, and risk factors.³

Initial Assessment

The diagnostic process usually begins with a thorough medical history and physical examination. Patients may report symptoms such as irregular or heavy menstrual bleeding, postmenopausal bleeding, or infertility.³ A pelvic examination is performed to check for any visible abnormalities.⁴

Imaging Techniques

Transvaginal Ultrasound (TVUS). This is often the first-line imaging tool used to evaluate the uterus. TVUS can detect endometrial thickening, which may indicate the presence of polyps. An endometrial thickness greater than 4 mm in postmenopausal women is considered abnormal and warrants further investigation.³

Sonohysterography (SIS). Also known as saline infusion sonography, this technique involves instilling saline into the uterine cavity during ultrasound. It provides better visualization of polyps by creating a contrast between the polyp and the surrounding fluid.^2,3 SIS has been shown to have higher sensitivity and specificity compared with conventional TVUS.⁵

Hysteroscopy. This procedure allows direct visualization of the uterine cavity using a thin, flexible telescope. It is considered the gold standard for diagnosing uterine polyps as it enables both visualization and biopsy of suspicious lesions.^2–4

Tissue Sampling

Endometrial Biopsy. This involves collecting a small sample of endometrial tissue for laboratory analysis. While it can detect some polyps, it may miss others, especially if they are small or located in areas not reached by the biopsy instrument.^2,3

Dilation and Curettage (D&C). This procedure involves dilating the cervix and scraping the uterine lining to obtain tissue samples. It can be used for both diagnosis and treatment of polyps.⁴

Guidelines and Recommendations

The American Association of Gynecologic Laparoscopists (AAGL) recommends hysteroscopy as the gold standard for diagnosing and treating endometrial polyps. They suggest that blind sampling techniques like endometrial biopsy or D&C alone are inadequate for accurate diagnosis.⁶

For postmenopausal women with bleeding, the American College of Obstetricians and Gynecologists (ACOG) recommends initial evaluation with TVUS or office endometrial biopsy. If the initial evaluation is inconclusive, further assessment with SIS or office hysteroscopy is recommended.⁷

The Journal of Obstetrics and Gynecology Canada provides comprehensive guidelines on diagnosing and managing endometrial polyps. Endometrial polyps are common in both pre- and postmenopausal patients, often associated with symptoms such as abnormal bleeding, postmenopausal bleeding, and infertility, though some patients may be asymptomatic.⁸

Transvaginal ultrasound is recommended as the initial diagnostic tool due to its safety and accessibility, despite variable accuracy. If ultrasound results are inconclusive, saline-infused sonohysterography (SIS) or 3D ultrasound can be considered. Hysteroscopy with guided biopsy is the gold standard for diagnosing and treating polyps, enabling complete resection, reducing recurrence, and providing a pathology specimen. Hysterosalpingography, CT, and MRI are not useful for polyp diagnosis.⁸

High-risk patients (over 60, postmenopausal, symptomatic, or taking tamoxifen) should be referred to a gynecologist for further evaluation. In asymptomatic, low-risk cases, expectant management may be considered. Blind sampling techniques, such as endometrial biopsy or dilation and curettage (D&C), are not recommended for diagnosing polyps.⁸

Hysteroscopic polypectomy is the preferred treatment for polyps, especially in patients seeking to improve fertility, as it enhances pregnancy outcomes. Bipolar energy should be used over monopolar energy to reduce the risk of electrosurgical burns, and tissue removal systems are preferred when available. If a polyp is found during in vitro fertilization stimulation, options like cycle cancellation or freezing embryos can be discussed, though cycle cancellation is not typically necessary.⁸ Overall, these guidelines emphasize targeted diagnostic tools, minimally invasive treatments, and careful management based on patient risk factors and reproductive goals.⁸

Uterine polyps can be managed through various treatment approaches, depending on factors such as the size of the polyps, associated symptoms, and the patient's overall health. For small, asymptomatic polyps, conservative management through watchful waiting may be recommended, as some polyps may disappear on their own. However, several options are available for those causing symptoms or requiring intervention.⁹

Medication can be an effective approach for managing symptoms and potentially shrinking polyps. Hormonal treatments such as progestins and gonadotropin-releasing hormone agonists can help regulate menstrual bleeding and temporarily stop periods, respectively.¹⁰ The Mirena® IUD, containing progesterone, has also shown promise in reducing the risk of polyp recurrence.⁹ It's important to note, however, that medication often provides only temporary relief, and polyps may return once treatment is discontinued.¹⁰

Surgical removal is often the preferred course of action for larger polyps, those causing significant symptoms, or potentially cancerous polyps.¹⁰ Hysteroscopic polypectomy is the most common procedure, performed as an outpatient surgery where a thin scope is inserted through the vagina and cervix to remove the polyps. In some cases, dilation and curettage (D&C) may be necessary for larger polyps.¹⁰ In rare instances, particularly if cancer is suspected, a hysterectomy might be recommended.⁹

The management of uterine polyps typically involves a multidisciplinary approach, bringing together various specialists to provide comprehensive care.⁹ Gynecologists play a central role, performing initial evaluations, diagnostic procedures, and often conducting polypectomies. They coordinate with radiologists who use imaging techniques for detection and assessment and pathologists who examine tissue samples to determine if polyps are benign or malignant.⁹ Endocrinologists can address underlying hormonal imbalances, while fertility specialists assist patients concerned about reproductive health.⁹ For surgical management, especially in high-risk patients, an anesthesia consult is often considered to ensure patient safety. Specialized surgical nurses are crucial to the process, being responsible for patient preparation before and after the procedure, intraoperative positioning, and arranging the correct surgical supplies. These nurses, along with other nursing staff, play a vital role in postoperative care, following up to assess treatment success and informing the care team of any concerns.³ This collaborative effort ensures that patients receive holistic care, addressing all aspects of their condition from diagnosis through treatment and follow-up, tailoring management strategies to individual needs, fertility goals, and overall health considerations.

Uterine polyps, while often benign, present a range of challenges due to their varied symptoms and potential implications for fertility and cancer risk. The etiology appears to involve hormonal, genetic, and inflammatory factors, contributing to their persistence and growth. Effective screening and diagnosis rely on a combination of clinical assessment and imaging, with hysteroscopy regarded as the gold standard for both diagnosis and treatment. Management strategies range from conservative approaches for small, asymptomatic polyps to medical or surgical interventions for larger or symptomatic growths. A multidisciplinary approach ensures comprehensive care, aligning treatment with patient-specific health and reproductive needs for optimal outcomes.

1. Nijkang NP, Anderson L, Markham R, Manconi F. Endometrial polyps: Pathogenesis, sequelae and treatment. SAGE Open Med. 2019;7:2050312119848247. doi:10.1177/2050312119848247
2. Mayo Clinic. Uterine polyps-Uterine polyps - Symptoms & causes. Accessed November 6, 2024. https://www.mayoclinic.org/diseases-conditions/uterine-polyps/symptoms-causes/syc-20378709
3. Mansour T, Chowdhury YS. Endometrial Polyp. In: StatPearls. StatPearls Publishing; 2024. Accessed November 6, 2024. http://www.ncbi.nlm.nih.gov/books/NBK557824/
4. WebMD. Uterine (Endometrial) Polyps: Causes, Symptoms, Treatments, and Prevention. Accessed November 6, 2024. https://www.webmd.com/cancer/cervical-cancer/uterine-polyps
5. City of Hope. Uterine Polyps: Symptoms, Causes, Diagnosis and Treatment. October 11, 2023. Accessed November 6, 2024. https://www.cancercenter.com/cancer-types/uterine-cancer/risk-factors/uterine-polyps
6. American Association of Gynecologic Laparoscopists. AAGL practice report: practice guidelines for the diagnosis and management of endometrial polyps. J Minim Invasive Gynecol. 2012;19(1):3-10. doi:10.1016/j.jmig.2011.09.003
7. American College of Obstetricians and Gynecologists. The Role of Transvaginal Ultrasonography in Evaluating the Endometrium of Women With Postmenopausal Bleeding. Accessed November 6, 2024. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2018/05/the-role-of-transvaginal-ultrasonography-in-evaluating-the-endometrium-of-women-with-postmenopausal-bleeding
8. Bougie O, Randle E, Thurston J, Magee B, Warshafsky C, Rittenberg D. Guideline No. 447: Diagnosis and Management of Endometrial Polyps. J Obstet Gynaecol Can. 2024;46(3). doi:10.1016/j.jogc.2024.102402
9. Cleveland Clinic. Uterine Polyps Treatment. Accessed November 7, 2024. https://my.clevelandclinic.org/services/uterine-polyps-treatment
10. Bezna T. Collaborative Approaches to Uterine Polyp Management: Insights for Obstetricians and Gynecologists. Caldera Medical. April 15, 2024. Accessed November 7, 2024. https://www.calderamedical.com/collaborative-approaches-to-uterine-polyp-management-insights-for-obstetricians-and-gynecologists/