No Two Fibroids Are Alike

Fibroids are like snowflakes – no two are alike!

The Internet is both a great source of information and confusion. Although we now have access to hundreds of drawings and photographs with several clicks of a mouse it is impossible to convey all the different varieties of fibroids. A complete discussion of the variation is beyond this chapter. However, what will follow is a very complete resource and will give you some insight into the classification, types and variations among fibroids. An appreciation of this understanding is important as it will give you some insight into why so many approaches to treatment exist.

Two snowflakes


There are many different classification systems for fibroids. In general, however, there are 3 main types of fibroids:

Subserous fibroids—these fibroids grow predominantly outside the uterus and bulge into the abdominal or pelvic cavity. Like all fibroids they can vary in size. Because they grow into the abdominal cavity—where there’s a lot of room—they can achieve a very large size before they produce symptoms. When you hear about “giant fibroids” that are the size of a melon (or larger) they are generally of this variety. Subserous fibroids, if they produce symptoms at all, can cause bloatedness and compression of the bladder (leading to urinary frequency) and bowel (leading to new-onset constipation). For the most part, however, subserous fibroids don’t cause any symptoms.

Intramural fibroids—the word “mural” means “wall”. An intramural fibroid is one that arises within and remains in the wall of the uterus. Technically, all fibroids start out as intramural fibroids but then may evolve as described below.

Most intramural fibroids do not cause symptoms until they reach a critical size. Fibroids that grow within the wall have limited space. Sooner or later their growth causes them to bulge in one of two directions—either into the uterine cavity (when they become known as submucous) or into the abdominal cavity (when they become known as subserous).

Women with intramural fibroids can experience heavy menstrual bleeding but that isn’t always the case. As fibroids encroach into the uterine cavity they tend to produce symptoms of heavy vaginal bleeding. Intramural fibroids can also increase the likelihood of infertility and pregnancy loss.

Submucous leiomyomas—I often say that “fibroids are like real-estate”. The “health value” –or the problems they cause–are all about location! Submucous fibroids “live” in the “neighborhood” of the inside of the uterine cavity.

Submucous fibroids—even ones that are no more than an inch (2-3 centimeters) in diameter can produce very heavy and prolonged menses. The reason is quite simple—the superficial blood vessels that fibroids contain often rupture at the time of menses and the resulting bleeding can be severe enough to require hospitalization and even blood transfusions.

Aside from causing very heavy menses, submucous fibroids can be responsible for infertility and miscarriages. Even once pregnancy is established submucous fibroids can cause a woman to undergo premature labor.


Generally speaking this “grading system” refers only to submucous leiomyomas as follows:

Grade 0 leiomyomas are entirely (90 – 100%) within the uterine cavity.

Grade 1 leiomyomas are between 50 and 90% within the cavity.

Grade 2 leiomyomas are between 0 and 49% within the uterine cavity.

The grading system was largely developed by hysteroscopists—gynecologists who specialize in surgery within the uterine cavity. The system was developed to assist gynecologists in determining which cases were simpler and which were more difficult—an important piece of information in giving advice to a woman about the best type of surgery for her.

In general, grade 0 are the easiest to remove while grade 2 are the most difficult to remove. Please keep in mind that there are many other factors besides type (subserous, intramural and submucous) and grade (0, 1, and 2) that determine the difficulty of fibroid removal and what methods are best suited for a particular case.

A comparison of Grade 0, Grade 1, and Grade 2 Leiomyomas


There is tremendous variability that one finds in women with respect to the number of fibroids they grow. Many of the women who are referred to us because of heavy or prolonged menses often have only 1 or 2 large myomas that are responsible for the bulk of their symptoms. In other instances the women we see have numerous–up to 20–small myomas each less than a centimeter in diameter.


There is little that you will find in the literature that speaks to “patterns” of fibroids but some understanding of this is worthwhile.

Several patterns of fibroids seem evident:

Solitary fibroids—In many women—at the time they present with issues such as infertility or abnormal menstrual bleeding—only a single fibroid is seen. The size can vary from 1-9 centimeters. While the removal of this solitary myoma doesn’t mean that others will not grow but often this seems to be the case.

Multiple small fibroids (less than 2 centimeters each)—In other women the pattern we see appears to involve many (4-20) small fibroids. While removal of many of these fibroids may alleviate their symptoms, it’s not possible to remove every last one. Young women (under the age of 40) with this pattern often have the potential for future problems if some of the fibroids left behind begin to grow.

Mixed pattern—Still other women have, what appears to be, a mixed pattern–one or two large or “dominant” fibroids together with multiple smaller ones. As you might expect, the existence of multiple smaller fibroids is especially problematic in young women (under 40) where the removal of 2 or 3 fibroids still leaves a “reservoir” of fibroids that have the potential to grow.