Uterine Diseases: Leiomyomas

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  • 0:07 Uterine Fibroids
  • 1:30 Types
  • 3:30 Symptoms
  • 4:10 Fibroid Growth
  • 5:37 Lesson Summary
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Lesson Transcript
Instructor: Heather Adewale

Heather has taught reproductive biology and has researched neuro, repro and endocrinology. She has a PhD in Zoology/Biology.

Did you know that you could have lumps growing inside your uterus and not even know it? Or, that they could interfere with pregnancy? Learn about what a uterine leiomyoma (also called a fibroid) is in this lesson.

What Are Uterine Fibroids?

You know how everything in science seems to have multiple names for the same thing? I mean, why can't they just pick one and stick with it, right? Well, diseases of the uterus are the same. One in particular has three different names. These are the uterine leiomyomas, also called uterine myomas or uterine fibroids. And yes, they all refer to the same thing!

To make things simpler, we will use the term fibroids. These are areas of excess cell growth in the smooth muscle of the uterus. They look kind of like tumors, but they aren't cancerous. Another term for a non-cancerous growth in the body is benign. This is a good thing considering that fibroids are the most common form of tumors in the pelvic region. That's the region shown below, where the reproductive organs are located. And, they can range in size from that of a bean to a golf ball or larger. Can you imagine a uterus full of golf balls? How uncomfortable!

The reproductive organs are located in the pelvic region.
uterus shown in pelvic region

In fact, about 1 in every 3-4 women over the age of 35 gets uterine fibroids! That's more than those diagnosed with breast cancer. Not only that, but they're more common in African-American women than other races.

Types of Fibroids

Okay, so now that we know what a fibroid is, let's take a look at the different types and some of the symptoms. What makes one fibroid type different from another is based on the location of the fibroid. It's like how the nails on your fingers are called 'fingernails' while those on your toes are called 'toenails,' but other than their location, they're essentially the same thing, right?

I know, you may be thinking, 'Aren't all fibroids located in the uterus?' And yes, they are, but if you remember back to your lessons on uterine anatomy, you may remember that the uterus is made up of three layers. Let's take a quick look. The outer layer shown below is the perimetrium, and it's the outer covering of the uterus. Underneath that is a thicker layer made up of smooth muscle cells: that's the myometrium. You can remember this one because 'myometrium' and 'middle' both start with the letter 'M,' and the myometrium is the middle layer! And, the innermost layer, the one that sheds during menses, is the endometrium. You may remember from other biology lessons that the prefix 'endo-' means 'inner' or 'under.' So, here in the uterus, the endometrium is the innermost layer, underneath the myometrium.

The perimetrium is the outer covering of the uterus.

The most common type of fibroids is that found in the myometrial layer. They often cause an increase in the general size of the uterus but don't project to the surface. Fibroids that can be seen from the outside as irregular projections or lumps on the uterine surface are located beneath the perimetrial lining. If the fibroid projects into the inner space inside the uterus, that means it's located in or directly beneath the endometrial lining of the uterus. These types of fibroids are more likely to cause symptoms.


In most cases, women with uterine fibroids are asymptomatic, meaning they don't display any symptoms. However, in some cases, fibroids can cause excessive bleeding during menstruation, cell death, infection, pain or trouble urinating, constipation or rectal pain, and abdominal pain. The most common culprits are the fibroids found near or in the endometrial lining of the uterus. In severe cases, these types of fibroids can also interfere with pregnancy if they decrease the space the baby has to develop.

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