Fibroids are smooth muscle tumors of the uterus. They grow from the muscle cells of the uterus and are also called uterine leiomyomas, or myomas. They are benign ( non-cancerous), and are the commonest tumours found in a young woman. Since they are so common ( about 25% of women in the childbearing group will have fibroids) , many infertile women will also be found to have fibroids. However, most fibroids do not affect fertility and can safely be left alone. Unfortunately, many doctors are very anxious to surgically remove these, and this unnecessary surgery can actually cause infertility !
Fibroids are classified according to their location and are of 3 types. The uterus has 3 layers - the inner lining which lines the cavity, called the endometrium; the wall of the uterus which consists of smooth muscle, called the myometrium; and the outer lining , called the serosa. A fibroid which grows in the muscular wall of the uterus is called an intramural ( "within the wall" ) fibroid. A fibroid which grows mainly on the outer surface of the uterus, under the serosa, is called subserosal. A fibroid which grows just under the uterine lining, inside the uterine cavity, is called a submucous or intracavitary fibroid.
Although the exact cause is unknown, the growth of fibroids, like all tumours, seems to be related to a gene that controls cell growth. Fibroid growth is also affected by the reproductive hormones estrogen and progesterone.
The majority of fibroids are small and do not cause any symptoms at all. Most fibroids in infertile women are detected on a routine pelvic examination; or during ultrasound scanning. However, submucous fibroids can cause increased uterine bleeding; and very large fibroids can cause pelvic pressure.
What about the relationship of fibroids and infertility ? It's easy to understand how a submucous fibroid which protrudes into the uterine cavity or causes distortion of the uterine cavity may act as a foreign body, and present a mechanical barrier to implantation. However, most other fibroids do not affect fertility. This is still controversial, because some doctors believe that intramural fibroids may cause an alteration or reduction of blood flow to the uterine lining , making it more difficult for an implanted embryo to grow and develop.
Most women with fibroids have completely normal pregnancies and deliver healthy babies with no complications. Women with large fibroids may have an increased risk of some problems during pregnancy, however, such as breech presentation of the fetus, premature rupture of the "bag of waters", and abruptio placenta (a condition in which the placenta separates from the uterine wall during the pregnancy).
Most fibroids are diagnosed during an ultrasound examination. One limitation of ultrasound is the inability in many cases to determine the relationship of the fibroids to the uterine cavity . This is why additional tests may need to be performed. These include:
In an infertile woman this is a key diagnostic tool, because it allows us to detect fibroids that are within the uterine cavity or cause significant distortion of the cavity.
This is an excellent test for determining the relationship of fibroids to the uterine cavity. During the ultrasound examination, saline is instilled into the uterine cavity through a catheter. This separates the walls of the uterine cavity just enough to allow an ultrasound to detect abnormalities inside the cavity.
The hysterosalpingogram uses radiopaque dye to visualise the uterine cavity; and can diagnose only submucous fibroids, which appear as "filling defects" or distort the cavity.
Magnetic resonance imaging is an expensive way of defining the location and size of fibroids, and is rarely used.
Most fibroids in infertile women do not need any treatment at all, because they do not affect fertility or pregnancy. They are best left alone ! In fact, unnecessary surgery can actually reduce your fertility, because it causes adhesions and scarring which can damage the tubes.
However, submucous fibroids in infertile women ( those within the uterine cavity or causing significant distortion of the cavity ) do need to be removed; and these are best removed by doing an operative hysteroscopy. This requires a skilled surgeon, who should document the surgery on video or CD.
The standard operation for removing fibroids is called a myomectomy. This was traditionally done through open surgery; and can also be performed laparoscopically. However, this is of very limited use in infertile women, because this surgery removes only subserosal and intramural fibroids, most of which can be left alone in infertile women.