The Fundamentals of Uterine Fibroids
Do you or someone you know have uterine fibroids? You are in good company because these benign smooth muscle tumors of the uterus are very common, with up to 80% of all women having fibroids by the time they go through menopause. Certain populations are disproportionately affected with uterine fibroids, including Black women at a rate of up to 90% of their lifetimes. Other factors that can increase the risk of uterine fibroids include family history, high body mass index, increasing age, and lack of prior pregnancy. While common, the vast majority of women will have little or no symptoms as a result of fibroids. Those who are symptomatic may notice pelvic pain and pressure, pain with intercourse, urinary frequency, constipation, or heavy menstrual periods, sometimes resulting in anemia due to excessive monthly blood loss.
Although uterine fibroids are rarely the sole cause of infertility or pregnancy loss, uterine fibroids may be discovered during the evaluation for either, during a pelvic ultrasound. This leads many women to assume their fibroids caused their reproductive issue. Overall there are various mechanisms by which uterine fibroids may impact reproductive outcomes. Uterine fibroids may:
- Block the fallopian tubal ostia or the cervix, affecting transport of oocyte and sperm
- Diminish blood flow to the endometrium, affecting implantation rates and IVF outcomes
- Impair movement of the of the myometrium, the muscle layer of the uterus
- Increase local inflammation, if fibroids are degenerating
- Disrupt the physiologic hormonal environment of the endometrium
When trying to determine the contribution of uterine fibroids to infertility or pregnancy loss, location matters. Subserosal fibroids, those right under the outermost layer of the uterus tend to have the least impact on reproductive outcomes. Submucosal fibroids, those within the endometrium where a pregnancy would grow, have the most impact on reproductive outcomes. Submucosal fibroids are associated with decreased implantation, clinical pregnancy and ongoing pregnancy rates. Outcomes for intramural fibroids, those within the muscle layer of the uterus, lie in between subserosal and submucosal. Although the study data is mixed, here we often consider the number and size of fibroids to determine reproductive impact. If less than 4 cm and not protruding into the uterine cavity or obstructing the fallopian tubes, the reproductive risk can be considered small.
Although fibroids can increase the risk of miscarriage, preterm delivery, breech position of the baby, need for cesarean section or uterine pain are the uterus grows with pregnancy, many women with uterine fibroids continue to have healthy pregnancies and carry to term. Fibroids are monitored on ultrasound throughout the pregnancy, as the baby grows.
Prior to pregnancy, some women may require treatment for uterine fibroids including surgical removal or myomectomy. The options for myomectomy depend on the size and location of fibroids and range from hysteroscopic to laparoscopic or robot-assisted to abdominal surgery. Each case is considered individually to optimize health for the patient and future pregnancy as well as alleviate fibroid related symptoms. Most women, if asymptomatic, will need no intervention at all. For more in management of uterine fibroids, click here.
If you have uterine fibroids and want to understand how it may impact your reproductive health, schedule a consult with a reproductive endocrinologist who can work with you and your obstetrician/gynecologist on the best plan for you.