Uterine fibroids and polyps are two of the most common non-cancerous growths found in the female reproductive system, often affecting women during their reproductive years. While both conditions can cause similar disruptive symptoms, such as abnormal uterine bleeding, they originate from different tissues and have distinct biological characteristics. Understanding these differences is helpful for diagnosis and treatment planning.
Defining Fibroids and Polyps: Composition and Location
Uterine fibroids (leiomyomas) are dense, firm tumors arising from the smooth muscle tissue (myometrium) within the uterine wall. They are composed primarily of muscle and fibrous connective tissue, and their classification is based on their location within the uterus, which influences symptoms.
Fibroids can grow in three locations: intramural (within the muscular wall), subserosal (on the outer surface), or submucosal (beneath the uterine lining). They range significantly in size, from nearly microscopic nodules to large masses that distort the shape of the uterus.
Polyps, most commonly endometrial polyps, are soft, localized overgrowths of the endometrium. Unlike fibroids, they are glandular and vascular, containing a high concentration of blood vessels. These growths typically attach to the uterine wall by a thin stalk (pedunculated) or a broader base (sessile).
Endometrial polyps are confined to the uterine cavity, though cervical polyps can also form on the neck of the uterus. They are generally much smaller than fibroids, usually measuring only a few millimeters to a few centimeters. The distinction between muscle tissue origin for fibroids and lining tissue origin for polyps is central to their biology and clinical behavior.
Identifying Shared and Unique Symptoms
Both fibroids and polyps commonly manifest through abnormal uterine bleeding (AUB). Heavy menstrual bleeding (menorrhagia) is a frequent shared symptom, alongside general pelvic discomfort. However, the nature and severity of bleeding often differ between the two conditions.
Fibroids often cause extremely heavy and prolonged menstrual periods, sometimes leading to significant blood loss and iron-deficiency anemia. Their bulk and position can also create pressure symptoms, such as frequent urination or difficulty emptying the bladder. Large fibroids located toward the back of the uterus may press on the colon or rectum, resulting in chronic constipation and pelvic heaviness.
Polyps, due to their delicate, vascular nature, typically cause intermenstrual bleeding, appearing as spotting or light bleeding between regular periods. They are also a common cause of post-coital bleeding and unexpected bleeding after menopause. Acute, severe pain accompanied by a fever may signal fibroid degeneration, which occurs when the tumor outgrows its blood supply.
Hormonal Influences and Risk Factors
The growth of both fibroids and polyps is influenced by hormones, particularly estrogen, which is why both growths tend to shrink after menopause when estrogen levels decline. Fibroids possess a higher concentration of receptors for both estrogen and progesterone than the surrounding uterine muscle tissue. This hormonal sensitivity fuels their proliferation throughout the reproductive years.
A strong genetic component is associated with fibroids; a woman’s risk increases three-fold if her mother or sister had them. Fibroids are also more common in African American women, who tend to experience an earlier age of onset and more severe symptoms.
Endometrial polyps are also linked to conditions that increase estrogen stimulation or local inflammation. Obesity is a risk factor for polyps because fat cells produce estrogen, leading to endometrial overgrowth. The use of the breast cancer drug Tamoxifen significantly increases the risk of polyp formation in postmenopausal women because it acts as an estrogen stimulator in the uterus.
Diagnostic Procedures and Treatment Approaches
Diagnosis typically begins with a transvaginal ultrasound, which provides images of the uterine structures. To clearly visualize growths protruding into the uterine cavity, a specialized imaging technique is often necessary. Saline Infusion Sonohysterography (SIS) involves injecting sterile saline into the uterus during an ultrasound to distend the cavity, allowing for clearer differentiation between polyps and submucosal fibroids.
Hysteroscopy is considered the gold standard for evaluating the uterine cavity, using a thin, lighted scope inserted through the cervix to directly view the growths. When polyps are present, a biopsy is often performed during hysteroscopy to rule out malignancy, which is a consideration, especially in postmenopausal women.
Treatment approaches are determined by the severity of symptoms, the size and location of the growths, and the patient’s desire for future fertility. For fibroids, medical management often begins with hormonal birth control or progestin-releasing intrauterine devices (IUDs) to control heavy bleeding.
Gonadotropin-releasing hormone (GnRH) agonists, such as leuprolide, can temporarily shrink fibroids by inducing a menopause-like state. They are generally used for a limited time, often before a planned surgery.
Surgical options for fibroids include myomectomy, which selectively removes the fibroids while preserving the uterus, making it the preferred option for women who wish to become pregnant. Uterine Fibroid Embolization (UFE) is a minimally invasive procedure where small particles are injected to block the blood supply to the fibroids, causing them to shrink. The definitive treatment is a hysterectomy (removal of the uterus), which eliminates recurrence.
Treatment for polyps is typically simpler, involving hysteroscopic polypectomy. This is the surgical removal of the polyp during the diagnostic hysteroscopy, and the procedure is often curative.