Uterine fibroids, also known as uterine leiomyomas, fibromyoma or fibroids, are benign smooth muscle tumors of the uterus, part of the female reproductive system. Most women with fibroids have no symptoms, while others may have painful or heavy menstrual bleeding. If large enough, they may push on the bladder, causing a frequent need to urinate. They may also cause pain during penetrative sex or lower back pain. Someone can have one uterine fibroid or many. It is uncommon but possible that fibroids may make it difficult to become pregnant. The exact cause of uterine fibroids is unclear. However, fibroids run in families and appear to be partly determined by hormone levels. Risk factors include obesity and eating red meat. Diagnosis can be performed by pelvic examination or medical imaging. Treatment is typically not needed if there are no symptoms. NSAIDs, such as ibuprofen, and paracetamol (acetaminophen) may help with pain. According to The Mayo Clinic, NSAIDs may help relieve pain tied to fibroids. Still, they do not reduce bleeding caused by fibroids as they are not hormonal medicines. Iron supplements may be needed in those with heavy periods. Medications of the gonadotropin-releasing hormone agonist class may decrease the size of the fibroids but are expensive and associated with side effects. If greater symptoms are present, surgery to remove the fibroid or uterus may help. Uterine artery embolization may also help. Cancerous versions of fibroids are very rare and are known as leiomyosarcomas. They do not appear to develop from benign fibroids. About 20% to 80% of women develop fibroids by the age of 50. In 2013, it was estimated that 171 million women were affected worldwide. They are typically found during the middle and later reproductive years. After menopause, they usually decrease in size. In the United States, uterine fibroids are a common reason for surgical removal of the uterus.
Signs and symptoms Some people with uterine fibroids do not experience any symptoms. However, abdominal pain, anemia, and heavy or increased bleeding can be signs of fibroids. There may also be pain during sexual intercourse, depending on the location of the fibroid. During pregnancy, they may also be the cause of miscarriage, bleeding, premature labor, or interference with the position of the fetus. A uterine fibroid can cause rectal pressure. The abdomen can grow larger, mimicking the appearance of pregnancy. Some large fibroids can extend out through the cervix and vagina. While fibroids are common, they are not a typical cause for infertility, accounting for about 3% of reasons why a woman may not be able to have a child. The majority of people with uterine fibroids will have normal pregnancy outcomes. In cases of intercurrent uterine fibroids in infertility, a fibroid is typically located in a submucosal position. It is thought that this location may interfere with the function of the lining and the ability of the embryo to implant.
Risk factors Some risk factors associated with the development of uterine fibroids are modifiable. Fibroids are more common in obese women. Fibroids are dependent on estrogen and progesterone to grow and therefore are most relevant during the reproductive years.
Diet Diets high in fruits and vegetables tend to lower the risk of developing fibroids. Fibers, vitamin A, C, and E, phytoestrogens, carotenoids, meat, fish, and dairy products are of unclear effect. Normal dietary levels of vitamin D may reduce the risk of developing fibroids.
Genetics Fifty percent of uterine fibroids demonstrate a genetic abnormality. Often, a translocation is found on some chromosomes. Fibroids are partly genetic. If a mother has fibroids, the risk in the daughter is about three times higher than average. Black women have a 3–9 times increased chance of developing uterine fibroids than white women. Only a few specific genes or cytogenetic deviations are associated with fibroids. 80–85% of fibroids have a mutation in the mediator complex subunit 12 (MED12) gene.
Familial leiomyomata
A syndrome (Reed's syndrome) that causes uterine leiomyomata along with cutaneous leiomyomata and renal cell cancer has been reported. This is associated with a mutation in the gene that produces the enzyme fumarate hydratase, located on the long arm of chromosome 1 (1q42.3-43). Inheritance is autosomal dominant.
Pathophysiology
Uterine fibroids are leiomyomas that occur in the uterus. Fibroids grossly appear as round, well-circumscribed (but not encapsulated), solid nodules that are white or tan and show a whorled appearance on histological section. The size varies, from microscopic to lesions of considerable size. Typically, lesions the size of a grapefruit or bigger are felt by the patient herself through the abdominal wall.
Microscopically, tumor cells resemble normal cells (elongated, spindle-shaped, with a cigar-shaped nucleus) and form bundles with different directions (whorled). These cells are uniform in size and shape, with scarce mitoses. There are three benign variants: bizarre (atypical), cellular, and mitotically active. The appearance of prominent nucleoli with peri-nucleolar halos should alert the pathologist to investigate the possibility of the extremely rare hereditary leiomyomatosis and renal cell cancer (Reed) syndrome.
Location and classification
Growth and location are the main factors that determine whether a fibroid causes symptoms and problems. A small lesion can be symptomatic if located within the uterine cavity, while a large lesion on the outside of the uterus may go unnoticed. Different locations are classified as follows:
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