Uterine fibroids (leiomyomas) are non-cancerous muscular growths that develop within the walls of the uterus. While many people experience no symptoms, the most common issue is heavy menstrual bleeding, medically termed menorrhagia. This excessive blood loss can severely impact daily life and often leads to anemia. Understanding the physical and biological mechanisms by which these growths disrupt the normal menstrual cycle is the first step toward effective management.
Understanding Uterine Fibroids
Fibroids are common, affecting up to 80% of women by age 50, though not all will require treatment. These growths are classified based on their location within the uterine structure, and this placement directly influences the likelihood and severity of bleeding. The three primary types are subserosal, intramural, and submucosal.
Subserosal fibroids grow on the outer surface of the uterus, typically causing bulk symptoms like pelvic pressure but rarely leading to heavy bleeding. Intramural fibroids are situated within the muscular uterine wall, where they can cause both bulk symptoms and heavy flow. Submucosal fibroids, however, push into and distort the uterine cavity, making them the type most strongly associated with significant menstrual blood loss, even when they are relatively small.
Biological Causes of Excessive Bleeding
The presence of fibroids initiates several biological changes that interfere with the regulation of menstrual blood flow. One primary mechanism involves the deformation of the uterine cavity, specifically by submucosal fibroids. These growths increase the overall surface area of the endometrium, the uterine lining that sheds each month. A larger shedding surface naturally results in a greater volume of blood loss during menstruation.
Fibroids also physically impair the myometrium, the thick muscle layer of the uterus responsible for contractions. After the endometrial lining sheds, the myometrium must contract firmly to compress the blood vessels and stop the flow, a process called hemostasis. Intramural fibroids embedded within this muscle tissue prevent these contractions from being effective, leading to prolonged and heavier periods because the vessels remain open longer.
Fibroids can also alter the local vascular environment, promoting the formation of new blood vessels through a process called angiogenesis. These newly formed vessels around the fibroid tend to be fragile, irregular, and highly prone to rupture. This dramatically increases the available blood supply and the ease with which bleeding occurs. Changes in local growth factors, such as prostaglandins, also contribute to abnormal blood vessel integrity and increased flow.
Confirming Fibroids as the Source
When a patient presents with excessive bleeding, a healthcare provider must first confirm that fibroids are the actual cause and not another gynecological condition. The initial diagnostic tool is typically a transvaginal ultrasound, a non-invasive procedure that uses sound waves to map the uterus, confirming the presence, size, and location of the fibroids.
For a more detailed view of the uterine cavity, especially when submucosal fibroids are suspected, a saline-infusion sonohysterography may be used. This technique involves injecting sterile salt water into the uterus during an ultrasound to better visualize the lining and any growths distorting the space. Hysteroscopy, which uses a slender camera inserted through the cervix, allows for direct visualization of the cavity and is often necessary to assess the most problematic fibroids.
Options for Managing Bleeding
Interventions for fibroid-related bleeding are selected based on the severity of symptoms, fibroid location, and the patient’s desire for future fertility.
Medical Management
Medical management often serves as the first line of defense.
- Hormonal therapies, such as combined oral contraceptives or the levonorgestrel-releasing intrauterine device (LNG-IUD), regulate the cycle and reduce blood flow.
- Non-hormonal options, such as tranexamic acid, can be used during menses to promote clotting and significantly reduce blood loss.
Minimally Invasive Procedures
These treatments target the fibroids directly.
- Uterine Artery Embolization (UAE) involves blocking the blood supply to the fibroids, causing them to shrink and alleviating symptoms.
- Radiofrequency ablation uses heat energy to destroy the fibroid tissue.
Surgical Solutions
Surgical approaches offer the most definitive solutions. Myomectomy is the procedure of choice for women who wish to preserve their uterus and fertility, as it involves the surgical removal of only the fibroids. In cases of severe symptoms where fertility is no longer a concern, a hysterectomy (the complete removal of the uterus) provides a permanent cure for fibroid-related bleeding.