Uterine Fibroids and Their Relationship with Fertility

In general terms, the presence of fibroids in patients who wish to have children is progressively increasing. This rise is justified by the fact that the age of motherhood is being delayed.

Studies related to uterine fibroids estimate that up to 70% of women develop fibroids at some point in their lives, with the highest incidence occurring after the age of 50.

• What are uterine fibroids
• Classification by location
• Symptoms
• Diagnosis

What are uterine fibroids?

Uterine fibroids (UF), also known as leiomyomas or fibromyomas, are the most common solid tumors of the female pelvis. They originate from the myometrium and consist of an abundant extracellular matrix surrounded by a thin pseudocapsule of connective tissue and compressed muscle fibers.

The appearance of uterine fibroids may be linked to genetic and hormonal factors. They usually develop during a woman's fertile years.

Although the exact cause of uterine fibroids is not known, their growth can be influenced by hormones such as estrogen and progesterone. Currently, cytokines and other growth factors related to fibrosis and angiogenesis also appear to play a role.

Although they usually do not cause problems, in some cases they can produce significant symptoms. If they grow large enough, they may hinder fertility or complicate pregnancy, in which case removal might be necessary.

Classification of fibroids

Once a patient is diagnosed, fibroids can be classified according to their location:

• Subserosal: Located on the outer surface of the uterus, deforming the serous membrane. These represent 55% of fibroids.
• Intramural: Found within the thickness of the muscular wall, not affecting the serous or mucous membranes. Around 40% of fibroids are intramural.
• Transmural: Located within the muscular wall and deform both the serosa and the endometrial mucosa.
• Submucosal: Develop just beneath the endometrium, displacing it as they grow. These represent about 5% of fibroids.

Wamsteker’s classification further divides submucosal fibroids into three types:

• Type 0: The fibroid is entirely located within the uterine cavity, either sessile or pedunculated.
• Type I: The fibroid has an intramural extension of less than 50%.
• Type II: The fibroid has an intramural extension greater than 50%.

Clinical Symptoms of Uterine Fibroids

The presence of fibroids can lead to a number of conditions, such as:

• Heavy menstrual periods or abnormal uterine bleeding.
• Pain and discomfort symptoms, including a feeling of pressure, compressive symptoms in nearby organs, and lower back pain.
• They may contribute to fertility problems. As a sole cause of infertility, fibroids are present in about 3% of patients. They are also associated with recurrent miscarriages.
• The likelihood of developing cancer from a uterine fibroid is rare—only about 1 in 10,000 patients may develop a malignant tumor. Only 0.5% of fibroids become malignant tumors in women, known as sarcomas.

When symptoms appear, the diagnosis and treatment of fibroids will depend on their number, size, and location.

Diagnosis: How are uterine fibroids detected?

Some patients may experience symptoms that serve as warning signs, while many others may be asymptomatic. In both cases, the annual check-up with a gynecologist, through a transvaginal pelvic ultrasound (which uses sound waves to produce images), can detect the presence and size of fibroids.

To assess the extent of the impact on the uterine cavity, additional procedures may be needed, such as:

• Ultrasound: The main diagnostic tool for fibroids, allowing the determination of size and intracavitary involvement.
• Sonohysterography: The instillation of fluid into the uterus helps define the intracavitary portion of fibroids more clearly.
• Hysteroscopy: A small lens is inserted into the uterine cavity, allowing visualization on a video screen. It is the gold standard for evaluating fibroids in terms of size, location, and grade. This exam also assesses whether the fibroid can be resected hysteroscopically. The angle formed by the fibroid and the uterine wall is key in assessing its intracavitary component; the sharper the angle, the more intracavitary the fibroid is.
• Hysterosonography: Involves injecting fluid into the uterine cavity followed by a transvaginal pelvic ultrasound.
• Magnetic Resonance Imaging (MRI): An excellent method to evaluate the relationship between the fibroid and the myometrium. It’s a non-invasive medical test that uses a strong magnetic field to produce images.

Despite their frequent occurrence, uterine fibroids are not usually a cause for serious concern, and there are various treatment options available to manage any discomfort they may cause.

If you're considering pregnancy and have uterine fibroids, we recommend reading our article on the different treatment options available.

Relationship Between Fibroids and Fertility

The connection between uterine fibroids and infertility is complex and not fully understood. Fibroids are believed to impact fertility through several mechanisms, including:

• Mechanical effect: Fibroids can alter the shape and size of the uterus, making it difficult for a fertilized egg to implant.
• Distortion of the endometrial cavity: Submucosal fibroids, located inside the uterine cavity, can distort the endometrial surface, hindering fertilization and implantation.
• Blockage of tubal ostia: Fibroids can block the fallopian tubes, preventing sperm from reaching the egg or stopping a fertilized egg from reaching the uterus.
• Altered uterine contractility: Fibroids can interfere with normal uterine contractions, complicating implantation and embryo development.
• Disruption of gamete transport: Fibroids can affect blood flow to the ovaries and fallopian tubes, impairing egg maturation and sperm transport.

Remember, your annual check-up with a trusted gynecologist is essential for prevention, and preparing for pregnancy ahead of time can help you feel more at ease throughout the journey.

Do you have any questions or need more information?

At Fertility Madrid, we specialise in treatments such as egg donation, in vitro fertilisation and artificial insemination, among others.

Please do not hesitate to contact our professionals at our fertility clinic and they will answer all your questions without obligation.