Uterine fibroids (leiomyomas or myomas) are common non-cancerous growths that develop from the muscle tissue of the uterus. They vary significantly in size, ranging from tiny seedings to large masses that can distort the uterine shape. These growths affect a large percentage of women during their reproductive years, with some studies suggesting a prevalence of up to 70% by age 50. While the vast majority of women with fibroids will not experience fertility issues, their presence in some cases can create a barrier to conception.
Understanding Fibroids and Conception Rates
Fibroids are frequently found in women seeking fertility evaluations, but they are often an incidental finding rather than the primary cause of infertility. Only a small minority of infertility cases, between 1% and 2.4%, are solely attributed to uterine fibroids. Fibroids are present in approximately 5% to 10% of infertile patients, indicating that co-existence is common, but a direct cause-and-effect relationship is not always established.
The size and total number of fibroids are less significant for fertility than their exact placement within the uterus. Many small fibroids or a single large fibroid may not interfere with the reproductive process at all. Location determines the potential for mechanical obstruction or disruption of the uterine environment necessary for a successful pregnancy. This shifts the focus from simply having fibroids to assessing their specific impact on the uterine cavity and fallopian tubes.
How Fibroid Location Impacts Fertility
The effect of a fibroid on the ability to conceive is determined by its classification, based on its location within the uterine wall. The three main types are submucosal, intramural, and subserosal, each presenting a different level of risk to conception. Submucosal fibroids grow just beneath the inner lining of the uterus and protrude into the uterine cavity, making them the most likely to interfere with fertility. They physically distort the cavity’s shape, disrupting the proper implantation of an embryo.
Intramural fibroids grow within the muscular wall of the uterus, and their effect on fertility is less straightforward. They can reduce fertility if they are very large or grow close enough to the endometrium to distort the uterine cavity. Interference mechanisms involve altering blood flow to the uterine lining or disrupting muscular contractions that aid in sperm and egg transport. Studies indicate that intramural fibroids might also reduce the endometrium’s receptivity through biochemical changes, such as the reduction of implantation-related proteins.
Subserosal fibroids are situated on the outer surface of the uterus and typically grow outward. They are considered the least likely to affect conception and implantation because they do not interfere with the uterine cavity. Their removal is not usually recommended solely for fertility purposes, as evidence suggests they do not significantly reduce pregnancy rates. In rare instances, a large subserosal fibroid could block a fallopian tube, but this mechanical obstruction is uncommon.
Fertility-Focused Management and Treatment
When fibroids are determined to be the probable cause of infertility, the goal is to remove or shrink the growths while preserving the uterus for future pregnancy. Myomectomy, the surgical removal of fibroids, is often the preferred and most effective treatment for women who wish to conceive. The choice of surgical approach—hysteroscopic, laparoscopic, or open abdominal—depends heavily on the fibroid’s size and location. Submucosal fibroids, which are inside the cavity, are typically removed using hysteroscopic myomectomy, a minimally invasive procedure performed through the cervix.
Laparoscopic or robotic-assisted laparoscopic myomectomy is used for intramural and subserosal fibroids, offering smaller incisions and quicker recovery than open abdominal surgery. Abdominal myomectomy (laparotomy) is reserved for cases involving numerous, very large, or deeply embedded fibroids. Studies have shown that the probability of achieving pregnancy and live birth rates does not differ significantly among the three surgical methods.
Following myomectomy, the prognosis for conception is generally positive, with approximately 50% of previously infertile women achieving pregnancy. The benefit is most pronounced after the removal of submucosal fibroids, which significantly increases pregnancy rates. When numerous fibroids are removed (especially six or more), reproductive success may be lower, and patients may be more likely to require assisted reproductive technology.
Non-surgical management options, such as Gonadotropin-releasing hormone (GnRH) agonists, may be employed temporarily to shrink fibroids before surgery or conception attempts. These medications are not a long-term fertility solution because they halt ovulation, and the fibroids often regrow after the medication is stopped. Before intervention, diagnostic procedures like a saline infusion sonogram or hysteroscopy confirm that the fibroid is distorting the uterine cavity and is the likely cause of difficulty conceiving.