Uterine fibroids and endometrial polyps are two common, non-cancerous growths that develop within the uterus. These conditions frequently cause similar symptoms, such as abnormal bleeding, leading to confusion. While both are benign and highly prevalent, they arise from distinct tissues and occupy different spaces within the uterus. Understanding these biological and structural variations is the first step toward effective diagnosis and appropriate management.
Defining Uterine Fibroids
Uterine fibroids, also called leiomyomas or myomas, are solid tumors composed of smooth muscle and fibrous connective tissue. They are the most common benign tumors of the female reproductive tract, affecting up to 80% of women by age 50. Fibroids range dramatically in size, from microscopic to as large as a grapefruit.
Their precise location within the uterine wall determines their classification and influences the type and severity of symptoms.
Intramural Fibroids
Intramural fibroids are the most common type, developing within the muscular layer of the uterine wall.
Subserosal Fibroids
Subserosal fibroids grow on the outer surface of the uterus and can sometimes be attached by a stalk (pedunculated).
The third type is submucosal fibroids, which grow just beneath the endometrial lining and project into the uterine cavity. Even small submucosal fibroids can cause significant symptoms because they interfere directly with the uterine lining. Fibroid growth is influenced by the hormones estrogen and progesterone, causing them to develop during the reproductive years and often shrink after menopause.
Defining Endometrial Polyps
Endometrial polyps are localized overgrowths of the endometrium, the glandular and stromal tissue lining the inside of the uterus. These growths are soft, often finger-like projections confined to the uterine cavity. They attach to the uterine wall either by a narrow stalk (pedunculated) or by a broader, flatter base (sessile).
Polyps can occur singly or as multiple growths and range in size from a few millimeters to several centimeters. Unlike fibroids, which are dense muscle, polyps consist of glandular tissue, fibrous tissue, and blood vessels. While most endometrial polyps are benign, a small percentage can contain precancerous or cancerous cells, making evaluation important, especially in postmenopausal women.
Key Differences in Location and Symptom Presentation
The primary difference lies in their tissue origin and structural location. Fibroids originate from the myometrium (the muscular wall of the uterus) and can grow throughout the wall, on the outside, or beneath the lining. Polyps, in contrast, are formed from the endometrial lining and are always situated within the uterine cavity. This difference in composition—muscle versus glandular lining—is the main distinction.
These structural differences lead to variations in how symptoms manifest. Both conditions can cause heavy menstrual bleeding (menorrhagia) and irregular bleeding. However, polyps are more strongly associated with intermittent spotting, bleeding between periods (intermenstrual bleeding), or any bleeding after menopause.
Fibroids, particularly large or subserosal ones, are more likely to cause “bulk symptoms.” These include a feeling of pressure, pelvic pain, back pain, and frequent urination if the fibroid presses on surrounding organs. Small submucosal fibroids and polyps both affect the uterine cavity and often cause heavy bleeding and fertility issues.
Underlying Causes and Common Management Approaches
The precise cause for both fibroids and polyps is not fully known, but hormonal influence is a common thread. Both conditions are hormone-dependent, with growth stimulated by estrogen and progesterone. Genetic predisposition is also a factor, with risk elevated if there is a family history.
Management strategies differ based on tissue type, location, and symptom severity. For small, asymptomatic fibroids, a “watchful waiting” approach with regular monitoring is often adopted. Symptomatic fibroids may be treated with hormonal medications to manage bleeding or with surgical intervention, such as a myomectomy, which removes the fibroids while preserving the uterus.
For polyps, removal is generally recommended due to their potential to harbor abnormal cells and their strong association with abnormal bleeding. The standard procedure is hysteroscopic polypectomy, which uses a camera and specialized tools inserted through the cervix to visualize and remove the growth from the uterine cavity. Treatment success depends on the patient’s symptoms, the size of the growth, and whether they wish to preserve fertility.