A fibroid starts as a single cell that reproduces exponentially into a firm, rubbery mass of muscle and fibrous tissue. Unpredictable in size and behavior, fibroids can be as tiny as a pencil point or as large as a grapefruit, growing slowly or rapidly, either alone or in groups. When fibroids are small, women usually don't notice them, but as the tumors grow, women experience some common symptoms:
A woman's symptoms are influenced primarily by tumor location. Submucosal fibroids, those that project into the uterus, are thought to cause irregular bleeding. Subserosal fibroids, those that bulge to the outside, pressing on the bladder or ureters, are believed to trigger urinary problems. Tumors pressing on the rectum or spinal cord nerves from the back of the uterus result in either constipation or back pain. Pedunculated fibroids, which hang on a stalk either inside or outside of the uterus, can be painful if the tumor turns on its stalk. In rarer instances when a fibroid outgrows its blood supply, as the tumor degrades, it spins off by-products that seep into nearby tissue, causing acute pain.