How do uterine fibroids form?

Uterine fibroids are a common disease caused by many factors. Uterine fibroids are the most common benign tumors of the female genitalia, composed of smooth muscle and connective tissue. They are common in women aged 30-50 and rare in women under 20. According to autopsy statistics, about 20% of women over 30 have uterine fibroids. Because fibroids are mostly asymptomatic or rarely symptomatic, the incidence reported in clinical reports is much lower than the actual incidence of fibroids.

The exact cause is still unclear. Because fibroids are prone to occur during the reproductive period, are rare before puberty, and shrink or disappear after menopause, it is suggested that their occurrence may be related to female hormones. Biochemical tests have confirmed that the conversion of estradiol to estrone in fibroids is significantly lower than that in normal muscle tissue; the concentration of estrogen receptors in fibroids is significantly higher than that in surrounding muscle tissue, so it is believed that the high sensitivity of local fibroid tissue to estrogen is one of the important factors in the occurrence of fibroids. Studies have also confirmed that progesterone has the effect of promoting fibroid mitosis and stimulating fibroid growth. Cytogenetic studies have shown that 25%-50% of uterine fibroids have cytogenetic abnormalities, including the mutual transposition of the long arm fragments of chromosomes 12 and 14, the rearrangement of the long arm of chromosome 12, and the partial deletion of the long arm of chromosome 7. Molecular biological studies suggest that uterine fibroids are formed by the proliferation of monoclonal smooth muscle cells, and multiple uterine fibroids are formed by the proliferation of different clones of smooth muscle cells.