Uterine fibroids are common, non-cancerous growths that develop within or on the uterus, also known as leiomyomas or myomas. They can vary significantly in size, from tiny seedlings to large masses that can distort the uterus. Many individuals with fibroids experience no symptoms, yet for others, their size and weight can become a notable concern.
The Normal Uterus and Its Weight
The healthy, non-pregnant uterus is a relatively small organ. It typically measures about 7.5 to 8.0 centimeters (approximately 3 inches) in length, 4 to 5 centimeters in width, and 2.5 to 3.0 centimeters in thickness. Its shape is often compared to an upside-down pear or a fist. A typical non-pregnant uterus weighs around 50 to 70 grams, roughly 1.8 to 2.5 ounces. This weight reflects the organ’s muscular and supportive tissue, as well as its blood supply.
How Fibroids Increase Uterine Weight
Fibroids are benign growths composed of smooth muscle and fibrous tissue, similar to the uterine wall. They arise from a single muscle cell within the uterus that divides abnormally, physically adding mass and increasing its overall weight. Fibroids can range considerably in size, from microscopic to as large as a grapefruit or even a watermelon.
The number of fibroids also influences total uterine weight, as individuals can have single or multiple growths. They are often classified by location, such as intramural (within the uterine wall), subserosal (on the outside surface), or submucosal (just beneath the uterine lining). These growths are dependent on hormones like estrogen and progesterone, which stimulate their development and enlargement, further increasing uterine mass.
Typical and Extreme Weights of Fibroid-Affected Uteri
The weight of a uterus affected by fibroids can vary widely depending on the size, number, and composition of the growths. While smaller fibroids may only add a few grams, a single fibroid measuring around 7 cm might weigh about 1 pound, similar to an orange. A 10 cm fibroid, comparable to a grapefruit, could weigh approximately 1.5 to 2 pounds, and a 12 cm fibroid, akin to a small watermelon, might reach 2 to 3 pounds.
In significant cases, the uterus with fibroids can weigh several pounds, sometimes causing the abdomen to appear pregnant. Documented instances show extremely large fibroids substantially increase uterine weight. For example, a uterus with fibroids has been reported to weigh over 35 pounds in rare cases. Historical records mention a 140-pound fibroid, and a recent case involved a 61-pound fibroid removed in Singapore. These extreme examples highlight the considerable mass fibroids can add.
Why Increased Uterine Weight Matters
Increased uterine weight due to fibroids can lead to various physical symptoms, often prompting medical evaluation. The enlarged uterus can exert pressure on surrounding pelvic organs, contributing to discomfort. This pressure often manifests as pelvic heaviness, fullness, or abdominal distension and bloating.
The added weight and size can also lead to specific issues. Large fibroids pressing on the bladder may cause frequent urination or difficulty emptying it. Pressure on the rectum can result in constipation. Some individuals experience lower back or leg pain due to fibroids compressing pelvic nerves. These symptoms reflect the physical impact of an enlarged, heavier uterus on the body’s internal structures and daily functions.