Uterine fibroids, also known as leiomyomas or myomas, are common non-cancerous growths that develop from the muscle tissue of the uterus. They are prevalent, affecting an estimated 35% to 77% of women of reproductive age. The presence of these growths often raises concerns about a woman’s ability to conceive and carry a pregnancy. While fibroids can cause symptoms like heavy bleeding and pelvic pain, their impact on fertility is highly dependent on specific characteristics.
The Link Between Fibroids and Conception
Fibroids are not a definitive cause of infertility, and the majority of women who have them conceive naturally and have uncomplicated pregnancies. Fibroids are the sole factor identified in only 1% to 3% of all infertility diagnoses, requiring a comprehensive evaluation to rule out other common causes. The correlation becomes stronger in cases of unexplained infertility, where all other factors have been assessed and found normal. Fibroids may interfere with the reproductive process by altering the shape of the cervix, which affects sperm movement, or by obstructing the openings of the fallopian tubes. The size and position of the fibroid are the most significant determinants of whether it will interfere with the ability to become pregnant.
Location Determines Interference
The precise location of a fibroid within the uterine wall dictates its potential to interfere with conception and successful implantation. Fibroids are classified into three main types based on where they grow, each presenting a different level of risk to fertility. Understanding the location is more important than the total number or overall size of the growths.
Submucosal fibroids, which grow just beneath the inner lining and protrude into the uterine cavity, pose the greatest challenge to fertility. These fibroids significantly distort the shape of the uterine cavity, the space where an embryo must implant to establish a pregnancy. Studies show that the presence of submucosal fibroids can reduce the chance of live birth by as much as 70%.
Intramural fibroids are located within the muscular wall of the uterus itself and represent a moderate risk to fertility. If they grow large enough, especially exceeding five centimeters in diameter, they can stiffen the uterine wall or compromise the blood flow to the endometrium. This change in the uterine environment may interfere with implantation or the early development of the placenta. Data suggest that even non-cavity-distorting intramural fibroids can lower the odds of a live birth by approximately 44% compared to women without fibroids.
Subserosal fibroids grow on the outer surface of the uterus and are connected to the organ by a stalk or a wide base. Because they do not affect the uterine cavity or the muscular wall, they rarely interfere with conception or implantation. Fertility specialists agree that removing subserosal fibroids solely for the purpose of improving fertility is unnecessary. They have the least impact on a woman’s ability to become pregnant.
Medical Evaluation of Fibroid Impact
A thorough medical evaluation is necessary to determine if a fibroid is the source of fertility challenges. The initial assessment involves a transvaginal ultrasound, which uses sound waves to create detailed images of the uterus and ovaries. This non-invasive test helps the physician map the size, number, and general location of the fibroids.
For a clearer view of the uterine cavity, Saline Infusion Sonography (SIS), or hysterosonography, may be performed. This technique involves injecting sterile saline solution into the uterus to gently distend the cavity, providing superior imaging contrast during the ultrasound. SIS is useful for identifying submucosal fibroids and determining if they are distorting the cavity.
If a submucosal fibroid is strongly suspected, a hysteroscopy may be used for direct visualization. A thin telescope-like instrument is inserted through the cervix into the uterus during this procedure. This allows the specialist to directly see the inside of the cavity and confirm the precise location and size of any fibroid impacting the lining. These diagnostic tools help guide the decision on whether intervention is warranted to improve reproductive outcomes.
Treatment Options to Restore Fertility
Surgical removal is the fertility-sparing treatment for women whose fibroids interfere with conception. The procedure designed to remove fibroids while preserving the uterus is called a myomectomy. This approach is favored over treatments that compromise the uterine structure, such as uterine artery embolization, which is not recommended when future pregnancy is desired.
The method of myomectomy depends on the fibroid’s location. Submucosal fibroids are often removed using a hysteroscopic myomectomy, a minimally invasive procedure performed through the cervix without external incisions. For large intramural or subserosal fibroids, a surgeon may perform a laparoscopic myomectomy through small abdominal incisions, or an open abdominal myomectomy for the most complex cases.
Following the successful removal of problematic fibroids, especially those that distorted the uterine cavity, a woman’s chances of becoming pregnant can improve significantly. For those who still face challenges, assisted reproductive technologies (ART) like in vitro fertilization (IVF) may be considered. In these situations, myomectomy is performed first to optimize the uterine environment, improving the likelihood of successful implantation during the ART cycle.