Uterine fibroids (myomas or leiomyomas) are common, non-cancerous growths that develop from the muscle tissue of the uterus. They affect up to 80% of women by age 50, though many remain small and cause no symptoms. When these growths expand, they can press on nearby structures within the pelvic cavity. This physical interaction raises the question of whether fibroids can affect the digestive system, specifically causing constipation.
How Fibroids Interfere with Bowel Function
Fibroids can cause constipation primarily through mechanical compression. The uterus sits within the pelvic cavity, closely surrounded by organs like the large intestine and the rectum. As a fibroid grows, it acts as a mass that physically pushes against these adjacent structures.
This pressure is applied to the lower gastrointestinal tract, especially the sigmoid colon and the rectum, which are positioned behind the uterus. The mechanical force can narrow the internal channel (lumen) of the large bowel, making it difficult for stool to pass smoothly. This physical blockage slows the movement of waste, resulting in constipation symptoms like difficulty passing stool or a feeling of incomplete emptying.
The bulk of a large fibroid can also alter the normal positioning of surrounding pelvic organs. This distortion may interfere with peristalsis, the natural muscular contractions of the intestines necessary to propel stool. This disruption of normal bowel function contributes to sluggish digestion and infrequent bowel movements.
Why Location and Size Matter
Not all fibroids cause digestive issues; constipation depends heavily on the fibroid’s location and size. Fibroids that expand outward from the back wall of the uterus are the most likely to interfere with the bowel. Specifically, posterior subserosal fibroids grow on the outer surface toward the back, positioning them closest to the rectum and colon.
When these fibroids increase in size, they exert direct pressure on the bowel, leading to constipation and sometimes lower back pain. Smaller fibroids, generally under a few centimeters, often remain asymptomatic. Once a fibroid reaches a significant size, such as the size of a grapefruit or larger, the mechanical interference becomes more pronounced. Fibroids growing within the uterine wall (intramural) or into the cavity (submucosal) are less likely to cause constipation but may cause heavy bleeding.
Treatment Approaches for Fibroid-Related Constipation
For immediate relief from constipation, conservative measures can be helpful. Increasing dietary fiber, ensuring adequate hydration, and maintaining regular physical activity support improved bowel regularity. Over-the-counter stool softeners or mild laxatives may also provide temporary comfort by making stool easier to pass. These adjustments manage the symptom but do not address the underlying cause of the pressure.
Definitive relief requires treating the fibroid itself to remove the source of mechanical compression. Medical management often includes hormonal therapies, such as Gonadotropin-releasing hormone (GnRH) agonists. These agonists cause fibroids to shrink by temporarily reducing estrogen levels, which lessens the pressure on the bowel and alleviates constipation.
Minimally invasive procedures offer another option for reducing fibroid size. Uterine Fibroid Embolization (UFE) involves blocking the blood supply to the fibroids, causing them to shrink and resolving pressure-related symptoms. For larger, more symptomatic masses, surgical options are available. A myomectomy surgically removes the fibroids while preserving the uterus, which is appropriate for those wishing to maintain fertility. A hysterectomy, the complete removal of the uterus, is a definitive treatment that eliminates the fibroids entirely when symptoms are severe and fertility is not a concern.