Uterine fibroids, also known as leiomyomas, are non-cancerous growths that develop from the smooth muscle tissue of the uterus. While many women may have fibroids without any symptoms, these growths are composed of living tissue that requires a constant supply of blood and nutrients to survive. When a fibroid loses this supply, the cells within the growth begin to die in a process called degeneration or necrosis. This event marks a significant biological change in the fibroid, moving it from an active growth phase into a state of resolution.
Why Fibroids Degenerate
The fundamental reason a fibroid degenerates is a lack of sufficient blood flow, a condition known as ischemia. Fibroids grow by recruiting blood vessels from the surrounding uterine tissue, but sometimes their rate of growth exceeds the body’s ability to supply them with oxygenated blood. This common scenario of outgrowing the blood supply forces the fibroid to undergo spontaneous necrosis to shrink back to a sustainable size.
The rapid growth seen during pregnancy frequently causes a specific type of degeneration called necrobiosis, often referred to as red degeneration. Elevated hormone levels accelerate fibroid growth, which can lead to venous obstruction and hemorrhagic infarction, causing intense pain. In other cases, a pedunculated fibroid, which is attached to the uterine wall by a stalk, can twist and immediately sever its own blood connection.
Alternatively, degeneration can be intentionally induced through medical procedures designed to cut off the fibroid’s lifeline. Uterine Fibroid Embolization (UFE) is a minimally invasive treatment where an interventional radiologist inserts a catheter into the uterine arteries. Microscopic particles, known as embolic agents, are then injected to physically block the blood vessels feeding the fibroid tissue, leading to widespread necrosis.
Acute Symptoms During Fibroid Degeneration
The death of fibroid tissue triggers an intense, localized inflammatory response that results in acute, noticeable symptoms. The most characteristic symptom is the sudden onset of severe abdominal or pelvic pain, which is typically localized directly over the degenerating fibroid. This pain is often described as sharp, stabbing, or cramping, and it can last anywhere from a few days up to two weeks.
The dying cells release various inflammatory chemicals and breakdown products into the surrounding tissue. This chemical release is what causes the body’s acute reaction, including swelling and tenderness in the lower abdomen. The inflammatory cascade can also lead to a low-grade fever, usually defined as a body temperature between 100.4 and 102.2 degrees Fahrenheit.
This combination of pain and fever can sometimes be mistaken for other acute conditions, such as appendicitis or a ruptured ovarian cyst. Patients may also experience general malaise, fatigue, and nausea. Medical consultation is necessary to confirm the diagnosis, often using ultrasound or MRI to visualize the fibroid and the reduced blood flow within it.
The Body’s Long-Term Response to Necrosis
Once the acute phase of degeneration passes and the inflammation subsides, the body begins the long-term process of clearing the dead tissue. This cleanup process is a form of involution, which leads to a reduction in the fibroid’s overall size and determines the final outcome.
One of the most common final outcomes is hyaline change, where the fibroid tissue is replaced by a dense, proteinaceous material. This mechanism, sometimes called reclamation, involves the reabsorption of dead cells. It results in a smaller, less dense fibroid that is less likely to cause pressure symptoms.
Another common fate, particularly in older fibroids or those that have undergone induced necrosis, is calcification. This occurs when the dead tissue absorbs calcium deposits, causing the fibroid to harden into a dense, mineralized mass. While calcified fibroids are essentially inert and no longer growing, their size may remain stable.
The ultimate goal is a significant reduction in fibroid volume, which typically continues for six to nine months following the initial necrotic event. The cessation of the acute pain and the subsequent shrinkage of the fibroid usually results in a long-term improvement or complete resolution of the original fibroid-related symptoms, such as heavy menstrual bleeding and pelvic pressure.