Overview and Risk Factors
Uterine leiomyomas, or fibroids, are benign tumors of the uterus composed of smooth muscle and connective tissue. Fibroids are very common, present in at least one-quarter of women by the age of 40.
Fibroids are classified by anatomic location as intramural (within the myometrium), submucosal (underlying the endometrium), or subserosal (underlying the uterine serosa). There is no identifiable cause of uterine fibroids. However, estrogen is necessary for their growth, as many grow during pregnancy and then recede at menopause. Further, higher parity and oral contraceptive use have been shown to decrease the risk of fibroid formation.
Most uterine fibroid cases are asymptomatic. However, symptoms may include uterine bleeding, resulting in prolonged or heavy menstrual flow and possibly anemia; dysmenorrhea; urinary frequency and urgency; constipation, dyspareunia; and abdominal tenderness. Complications of pregnancy are more common in women with fibroids, including miscarriage, placental abruption, and premature labor.
African American women are up to 3 times more likely to have fibroids compared with white women, and often have more severe disease at a younger age.1
Age. Fibroids occur during the reproductive years, most commonly becoming clinically apparent during the fourth and fifth decades of life. They do not occur in prepubescent girls and usually shrink at menopause.
Genetics. Monozygotic twins have a 2 to 3 times greater risk of fibroids than dizygotic twins when one twin is affected.2
Pregnancy. Parity appears to decrease the risk of fibroids.
Oral contraceptive pills. Although these appear to be protective, the Nurses' Health Study showed an increased risk in women who used oral contraceptive pills at ages 13 to 16. Low-dose oral contraceptives and menopausal hormone therapy are not contraindicated in women with fibroids.
Some evidence suggests that cigarette smoking may decrease the risk of fibroids. Of course, the health risks of smoking far outweigh this potential benefit.
Fibroids may be suspected from the patient history, and a bimanual pelvic exam often confirms the diagnosis. The uterus is generally enlarged, mobile, and asymmetric. Extremely large fibroids may cause a palpable uterus on abdominal exam. Findings can be confirmed by imaging studies.
Transvaginal ultrasound can be used to detect and localize fibroids. However, for women with large uteri or more than 4 fibroids, it is less precise than MRI.4
Sonohysterography can better characterize submucosal fibroids than transvaginal ultrasound.
Pelvic MRI best localizes all types of fibroids, accurately assesses their size, and distinguishes fibroids from other growths (eg, adenomyomas, leiomyosarcomas). However, expense should be taken into consideration.
Hysterosalpingography is best reserved for fertility evaluations. It defines the contour of the endometrium and patency of the fallopian tubes.
Hysteroscopy provides direct visualization inside the uterus and can diagnose submucosal fibroids.
Most uterine fibroids are asymptomatic and need not be treated. Intervention depends upon a number of factors, including age (women approaching menopause may not require therapy as fibroids typically regress spontaneously), fertility concerns, and the location and size of the fibroids.
Surgical interventions are generally the most effective therapy for fibroids.
Myomectomy, via hysteroscopy, laparoscopy, or laparotomy, preserves childbearing potential but is at least as difficult for the surgeon and patient as hysterectomy. Hysteroscopy is best for submucosal fibroids. Laparotomy may be indicated for large or multiple fibroids.
Hysterectomy is a definitive treatment that offers clear symptomatic improvement in approximately 90% of fibroid patients who undergo it. The primary indication for hysterectomy is uncontrollable bleeding.
Other options for women who do not desire pregnancy include endometrial ablation via hysteroscopic myomectomy, cryotherapy, uterine artery embolization, or magnetic resonance-guided ultrasonic ablation.
Oral contraceptives or progestins (norethindrone acetate, levonorgestrel-containing intrauterine device) are the simplest treatments for abnormal bleeding associated with fibroids. These treatments can be continued until menopause in women who are not interested in pregnancy.
Gonadotropin-releasing hormone (GnRH) analogs (eg, leuprolide) can shrink fibroids prior to surgical removal. Symptoms will sometimes return with discontinuation of the therapy. GnRH analogs are generally not recommended for long-term medical management due to cost.
GnRH antagonists, mifepristone, asoprisnil, and androgens are under investigation for future use in treating fibroids.
Acute pain can be treated with nonsteroidal anti-inflammatory drugs (NSAIDs).
COX-2 inhibitors appear to benefit postmenopausal women,5 but further trials are needed to establish their effect for premenopausal women. However, potential cardiac and other risks of COX-2 inhibitors must be considered.
Evidence for a direct effect of diet on fibroid risk or progression is very limited. However, the production of certain growth factors (insulin-like growth factor I, epidermal growth factor) is a risk factor for fibroid growth,6 and evidence indicates that these may be the effectors of estrogen- and progesterone-mediated fibroid growth.7 Diets low in fat and high in fiber (eg, vegetarian diets) have the ability to modulate blood hormone concentration and activity8 and reduce levels of growth factors.9 These effects may underlie the results of studies that have found higher risk for fibroids in women who eat red meat more often than do others, and who are overweight, as described below. However, this does not necessarily mean that a diet change, even if effective, will alleviate symptoms rapidly enough to obviate the need for other treatments.
Epidemiologic studies indicate that the following factors are associated with increased risk of fibroids:
Red meat consumption. Available evidence suggests that women who eat more than one serving per day of red meat have a 70% greater risk for uterine myoma, compared with women who eat the least. Women who eat more than one serving per day of green vegetables have a 50% lower risk.10 However, this study should be repeated by other independent investigators before diet is assumed to be effective for preventing or treating fibroids.
Weight gain. A greater number of women with fibroids are obese, compared with the general population.11 In the Black Women's Health Study, the relationship between fibroids and obesity appeared to be "J-shaped." Compared with the thinnest women (body mass index [BMI] <20 kg/m2), risk appears to increase gradually in women with a BMI of 20 to 22.4 (34% increased risk), to a maximum risk in women with a BMI of 27.5 to 29.9 (47% increased risk), before falling in the most obese group (20% increased risk).12
Alcohol. Alcohol appears to increase the risk for fibroids. This risk is positively correlated with the number of years of alcohol intake and specifically with beer consumption. Compared with women who abstained from alcohol, those who had one or more drinks of beer per day had more than a 50% increased risk for leiomyomata.13
See Basic Diet Orders chapter.
What to Tell the Family
Uterine fibroids are benign growths that, while bothersome, are rarely life-threatening. In women who do not get relief from medications or diet changes, surgical options are available, depending on whether future pregnancy is desired.
1. Marshall LM, Spiegelman D, Barbieri RL, et al. Variation in the incidence of uterine leiomyoma among premenopausal women by age and race. Obstet Gynecol. 1997;90:967-973.
2. Kjerulff KH, Langenberg P, Seidman JD, Stolley PD, Guzinski GM. Uterine leiomyomas. Racial differences in severity, symptoms and age at diagnosis. J Reprod Med. 1996;41:483-490.
3. Treloar SA, Martin NG, Dennerstein L, Raphael B, Heath AC. Pathways to hysterectomy: insights from longitudinal twin research. Am J Obstet Gynecol. 1992;167:82-88.
4. Dueholm M, Lundorf E, Hansen ES, Ledertoug S, Olesen F. Accuracy of MRI and transvaginal ultrasonography in the diagnosis, mapping, and measurement of uterine myomas. Am J Obstet Gynecol. 2002;186:409-415.
5. Palomba S, Sammartino A, Di Carlo C, Affinito P, Zullo F, Nappi C. Effects of raloxifene treatment on uterine leiomyomas in postmenopausal women. Fertil Steril. 2001;76:38-43.
8. Barnard ND, Scialli AR, Hurlock D, Bertron P. Diet and sex-hormone binding globulin, dysmenorrhea, and premenstrual symptoms. Obstet Gynecol. 2000;95:245-250.
9. Allen NE, Appleby PN, Davey GK, Kaaks R, Rinaldi S, Key TJ. The associations of diet with serum insulin-like growth factor I and its main binding proteins in 292 women meat-eaters, vegetarians, and vegans. Cancer Epidemiol Biomarkers Prev. 2002;11:1441-1448.
10. Chiaffarino F, Parazzini F, La Vecchia C, Chatenoud L, Di Cintio E, Marsico S. Diet and uterine myomas. Obstet Gynecol. 1999;94:395-398.