Uterine fibroids are associated with both infertility and miscarriage depending on their size and location. However, not everyone with fibroids, even large ones, will have difficulty. Thus there is controversy as to the contribution fibroids have with reproductive difficulty.
There are three types of fibroids: submucous which are inside the uterine cavity; intramural which are within the muscle of the uterus; and subserous which grow on the outside of the uterus. Infertility and miscarriage may be caused by fibroids that distort the intrauterine cavity. Intramural fibroids greater than 2 inches or 5 cm in diameter could also cause reproductive difficulty by interfering with the blood supply to the implanting embryo. Fibroids on the outside of the uterus especially if they are pedunculated (on a stalk) are unlikely to be a reproductive problem, although, they may cause discomfort.
Fibroids grow in response to estrogen and most likely progesterone as well since both estrogen and progesterone receptors for growth have been identified in fibroids. Fibroids could grow in response to ovulation induction medications since they cause increased levels of estrogen. During pregnancy, fibroids may grow since pregnancy is a hyper-estrogen state. Fibroid growth during pregnancy is often associated with pain that may be ameliorated with medications.
Women having difficulty conceiving or who have had two or more miscarriages should be evaluated for the presence of uterine fibroids. Fibroids may be most easily identified by a pelvic examination, a pelvic ultrasound, and especially by a sonohysterosalpingogram.
If intrauterine fibroids are thought to be contributing to reproductive difficulty, minimally invasive surgical techniques using hysteroscopic resection can be performed. Laparoscopic surgery or myomectomy through a small abdominal incision may be needed to remove large intramural fibroids. If the uterine cavity is entered either using laparoscopic surgery or through an abdominal incision then the woman should not attempt pregnancy for 3 months after such surgery to give the uterus time to heal and a cesarean section would be needed for all subsequent deliveries. If the fibroids can be removed hysteroscopically without complication then pregnancy can be attempted the very next cycle following surgery and subsequent vaginal delivery could be anticipated.