Uterine fibroids are common, non-cancerous growths that develop within the uterus. While many individuals with fibroids experience no symptoms, others can face significant discomfort, particularly during their menstrual periods. This article explains the mechanisms linking fibroids to increased period pain.
Understanding Uterine Fibroids
Uterine fibroids, also known as leiomyomas or myomas, are non-cancerous growths composed of muscle and fibrous tissue that form in or on the wall of the uterus. They vary widely in size, from as small as a seed to as large as a grapefruit. Fibroids can develop in different locations: intramural fibroids grow within the muscular wall of the uterus, submucosal fibroids bulge into the uterine cavity, and subserosal fibroids form on the outside of the uterus. Their location, size, and number can influence whether they cause symptoms.
The Menstrual Cycle and Pain
The menstrual cycle involves the uterus preparing for potential pregnancy each month. If pregnancy does not occur, the uterus sheds its thickened lining, resulting in menstruation. This shedding involves the uterus contracting to expel the tissue and blood.
These muscular contractions are triggered by hormone-like substances called prostaglandins. Prostaglandins are produced in the uterine lining and cause the uterine muscles to tighten, which helps detach the lining. Higher levels of prostaglandins are associated with more intense uterine contractions and, consequently, more severe menstrual cramps.
Why Fibroids Intensify Period Pain
Fibroids can intensify menstrual pain through several mechanisms.
Hormonal Sensitivity
These growths are highly sensitive to the fluctuating levels of estrogen and progesterone throughout the menstrual cycle. Estrogen, in particular, stimulates the growth of uterine tissue, and fibroids often contain more estrogen receptors than normal uterine tissue, making them more responsive to hormonal changes. This hormonal sensitivity can cause fibroids to grow or become more active, contributing to increased discomfort, especially when hormone levels are higher.
Prostaglandin Production
Fibroid tissue itself can produce elevated levels of prostaglandins. This increased production of these pain-inducing chemicals leads to stronger and more frequent uterine contractions than would typically occur, resulting in more severe cramps. The uterus must work harder to expel its lining, especially when fibroids increase the surface area of the uterine lining that needs to be shed.
Physical Pressure
Large or numerous fibroids can exert pressure on the uterine wall and surrounding organs like the bladder or bowel. Submucosal fibroids, which grow into the uterine cavity, and intramural fibroids, embedded within the uterine wall, can directly interfere with the uterine lining and its ability to contract efficiently. This physical impingement can cause a feeling of fullness, heaviness, or sharp, localized pain, especially when the uterus is already contracting during menstruation.
Degeneration and Inflammation
In some instances, fibroids can outgrow their blood supply, leading to a process called degeneration. When a fibroid degenerates, parts of its tissue begin to die, releasing chemicals that cause acute, severe pain and inflammation. This type of pain can be very sharp and may last for several days to weeks. The presence of fibroids can also contribute to general localized inflammation within the uterus, further intensifying pain.
How Fibroid Pain Differs
Pain associated with uterine fibroids often differs from typical menstrual cramps. Fibroid-related pain is more intense, prolonged, or distinct. It may manifest as significant pressure, a sharp, stabbing sensation, or a persistent dull ache that can radiate to the lower back and thighs.
Unlike standard cramps that last a few days, fibroid pain can extend throughout the entire menstrual period and sometimes occur between periods. Fibroids also tend to cause heavier and longer menstrual bleeding. This increased blood loss can lead to symptoms like anemia and fatigue.