Uterine fibroids, also known as leiomyomas, are common, non-cancerous growths that develop within the muscular tissue of the uterus. They are the most frequent type of tumor found in the female reproductive system. While not malignant, their size, number, and location within the uterine structure determine the symptoms a person may experience. Understanding the specific type of fibroid is the first step toward effective management and treatment.
Defining Intramural Fibroids
Intramural fibroids are characterized by their growth location strictly within the muscular wall of the uterus, called the myometrium. The myometrium is the thick, middle layer of the uterine body composed mainly of smooth muscle cells. Intramural fibroids are the most common type, accounting for up to 70% of all cases.
They begin as small, abnormal muscle cells, and their growth is influenced by hormones like estrogen and progesterone. They can range from the size of a pea to as large as a grapefruit, significantly enlarging the uterus. As they expand, intramural fibroids can distort the shape of the uterine cavity. This location distinguishes them from submucosal fibroids, which bulge into the uterine cavity, and subserosal fibroids, which project outward from the outer surface.
Specific Symptoms Caused by Their Location
The symptoms associated with intramural fibroids are directly related to their position embedded within the muscular wall. A primary complaint is heavy menstrual bleeding and prolonged periods that can last seven days or more. The fibroids interfere with the uterus’s ability to contract effectively to stop blood flow after the uterine lining has shed. Distortion of the uterine cavity can also increase the surface area of the endometrium, leading to excessive blood loss.
The expanding growths also cause pelvic pressure and discomfort due to the enlargement of the uterus. If situated on the anterior wall, this mass effect can lead to frequent urination or difficulty emptying the bladder. Fibroids located on the posterior wall may cause low back pain, constipation, or discomfort during bowel movements by pressing on the rectum. Chronic, heavy blood loss can deplete the body’s iron stores, leading to anemia and fatigue.
How Intramural Fibroids Are Diagnosed
Intramural fibroids are often initially identified during a routine pelvic examination if a healthcare provider feels an enlarged or irregularly shaped uterus. To confirm the presence, size, and specific intramural location, imaging tests are necessary. Ultrasound is the most common initial test, using sound waves to create an image of the internal pelvic organs.
Both transabdominal and transvaginal ultrasound techniques are typically used to gain a clear view of the entire uterus and ovaries. The ultrasound provides detailed information on the fibroid’s depth within the myometrium, confirming its intramural classification. In cases where a more detailed mapping is needed, such as for surgical planning or when fibroids are very large, a Magnetic Resonance Imaging (MRI) scan may be performed. MRI offers a superior image contrast that can help differentiate fibroids from other conditions.
Treatment and Management Strategies
Management often begins with “watchful waiting” if the fibroids are small and symptoms are minimal. For those experiencing symptoms, initial treatments involve medications aimed at controlling heavy bleeding and pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) help manage pain and reduce blood flow during menstruation.
Hormonal therapies, such as birth control pills or progestin-releasing intrauterine devices (IUDs), help regulate the menstrual cycle and reduce bleeding. Gonadotropin-releasing hormone (GnRH) agonists temporarily shrink the fibroids by lowering estrogen and progesterone levels, but they are typically used short-term before surgery. When symptoms persist or fibroids are large, procedural and surgical options become necessary.
Surgical Options
A myomectomy removes the fibroids while preserving the uterus, making it suitable for those who wish to maintain future fertility. This procedure can be performed using minimally invasive techniques, though larger or deeply embedded fibroids may require an open abdominal approach. Alternatively, uterine artery embolization (UAE) is a minimally invasive technique where small particles are injected into the arteries supplying the fibroids, cutting off their blood supply and causing them to shrink. For definitive treatment, especially when symptoms are severe and fertility is not a concern, a hysterectomy removes the entire uterus and eliminates the possibility of fibroid recurrence.