Uterine fibroids are common, non-cancerous growths that develop in or on the uterus. They are also known as leiomyomas or myomas. These growths originate from the smooth muscle cells and fibrous connective tissue within the uterine wall. While fibroids are often benign and do not increase the risk of uterine cancer, their appearance can vary significantly. This article explores what these growths look like, both inherently and in different locations, their size and growth patterns, and how medical imaging helps visualize them.
Core Visual Characteristics
When directly observed, uterine fibroids are rounded or oval-shaped growths. They have a pale, whitish, or grayish color, distinguishing them from the surrounding redder uterine muscle. Fibroids are firm or rubbery.
Fibroids maintain a distinct boundary from the healthy uterine tissue, appearing as well-defined masses. Their internal structure, when cut, reveals a whorled or swirled pattern, similar to the grain of wood, due to the arrangement of muscle and fibrous tissue. This characteristic appearance helps medical professionals identify them.
Appearance Based on Location
The location of a fibroid influences its appearance within or on the uterus. Intramural fibroids, the most common type, grow embedded within the muscular wall. These can cause the uterus to appear enlarged or have an irregular shape.
Submucosal fibroids develop just beneath the uterine lining and protrude into the uterine cavity. Their presence can distort the shape of the uterine cavity, making it appear irregular. Subserosal fibroids are situated on the outer surface, causing the uterus to look lumpy or bumpy. Large subserosal fibroids can extend into the pelvis and may cause the abdomen to appear distended, resembling pregnancy.
Pedunculated fibroids attach to the uterus by a thin stalk or stem. These can be either subserosal, extending outward from the uterine surface, or submucosal, protruding into the uterine cavity. Their stalk-like attachment gives them a mushroom-like appearance.
Size and Growth Patterns
Uterine fibroids range widely in size, from microscopic to very large. They can be as small as a seed or a pea, or grow to the size of a cherry, plum, orange, grapefruit, or even a watermelon. A single fibroid may measure less than an inch, but clusters can become much larger, sometimes exceeding 20 centimeters in diameter.
Fibroids can grow slowly over many years, or more rapidly. While one fibroid is possible, multiple fibroids of varying sizes are common within the uterus. Very large fibroids can distend the abdomen.
Diagnostic Visualization
Medical professionals utilize various imaging techniques to visualize fibroids and confirm their presence and characteristics. Ultrasound is a primary diagnostic tool, where fibroids appear as solid, well-defined masses. On ultrasound scans, they present as hypoechoic (darker) compared to the surrounding uterine tissue, and their location and size can be determined. They may show acoustic shadowing or a mixed texture.
Magnetic Resonance Imaging (MRI) offers more detailed visualization of fibroids. On MRI scans, fibroids are clearly distinct from normal uterine tissue, showing low to intermediate signal intensity on T1 and T2-weighted images. MRI can reveal their internal structure, including areas of degeneration or calcification, and their precise relationship to surrounding organs. Direct visualization during minimally invasive procedures like hysteroscopy or laparoscopy reveals fibroids as firm, pale growths inside or outside the uterus.