Diagnosing Uterine Fibroids

Before we get started it’s important to know that while it may seem “easy” to diagnose fibroids it isn’t always the case. Some cases are “no brainers” – the physician can look at an ultrasound and have a clear understanding of size, position and the number of fibroids—and even recommend how to remove them. Oftentimes, however, this isn’t the case. Frequently, with commonly performed tests, it isn’t even possible to tell–with precision—just how many fibroids there are present in a given woman. In the pages below we’ll list some of the diagnostic tests as well as their limitations.

We’ll discuss 5 important methods to gain information about fibroids before offering surgery or another intervention. These diagnostic tests includes simple transvaginal ultrasound, saline infusion sonography (also known as a sonohysterogram), hysteroscopy, a combination called ultrasound-guided hysteroscopy and magnetic resonance imaging (MRI).


The beauty of transvaginal ultrasound lies in the fact that it is inexpensive, relatively non-invasive, nearly painless and can provide a great deal of information quickly. However, there are numerous disadvantages to ultrasound, too. In some instances the images (pictures) we obtain are imprecise. Often in women who have multiple fibroids it is difficult to determine the exact number, size and position of various myomas. Also, ultrasound cannot accurately determine the grade of a fibroid or whether its attachment point is simple (like a grape) or complex (broad based). Ultrasound examinations are extremely helpful in determining the size of fibroids provided there aren’t too many of them. The usefulness of ultrasound diminishes in instances when there are more than 3-4 fibroids.

Image taken from a Transvaginal Ultrasound
Transvaginal Ultrasound

Keep in mind that most women who we evaluate for abnormal menstrual bleeding or infertility require little–and sometimes no–additional testing beyond transvaginal ultrasound. The reason is simple—most women with menstrual abnormalities have a normal-appearing transvaginal ultrasound. Additional testing is often required when the ultrasound image is ambiguous, sampling of the lining tissue (endometrium) is necessary or if additional information is being sought that will be useful in determining whether or not intrauterine surgery is feasible.

In order gain more complete information, other tests—saline infusion sonography (also called SIS or a sonohysterogram), hysteroscopy, ultrasound guided hysteroscopy, or magnetic resonance imaging (MRI) may be required.

Image taken from a Transvaginal Ultrasound
Transvaginal Ultrasound


That’s a lot of names for the same test! For the purposes of this article we’ll use the term saline infusion sonography or SIS.

Saline infused sonography is a test that involves the use of ultrasound along with the injection of water into the uterus. The reason for the water injection is simple—water shows up as “jet black” on an ultrasound picture filled with various shades of “grey”. The shades of grey can look confusing even to experienced physicians. The injection of water into the uterus lets us know the exact location of the cavity and its relationship to the uterine fibroid.

During the test a catheter is inserted into the uterine cavity and water is injected through the cervix while an ultrasound examination is being performed. The water highlights the uterine cavity as well as any “masses” that occur within it—specifically fibroids and endometrial polyps. This turns out to be a very good method for measuring the fibroid or the polyp. In addition SIS is able to clarify the type of fibroid—submucous or intramural—as well as its grade and the size of the attachment point.

Image taken from a Transvaginal Ultrasound



Keep in mind that the SIS was invented in the 1980s when hysteroscopy with small diameter scopes was unavailable. You will learn more about hysteroscopy in the section below. It was a good test for its time but today we feel that there are better tests that offer more information. The SHG has several shortcomings.

  1. SIS involves the placement of a catheter into the cervix which requires a certain amount of manipulation and often causes cramps.
  2. SIS requires the injection of water into the uterus which distends it and—you guessed it—causes more cramps.
  3. SIS often produces an ambiguous image and incomplete information. When this happens a test called hysteroscopy (see section below) is often needed.
  4. When the SIS is negative it’s helpful. However, when the test shows growths within the uterine cavity it is often followed by other tests—namely hysteroscopy.
Diagram of an Hysteroscopic Examination of the Uterus

Since the invention of the SIS hysteroscopes have become smaller and smaller with diameters that are nearly identical to the catheter used for the saline infusion sonogram. With “scopes” now as small as catheters we, at The Center for Menstrual Disorders, feel it makes more sense to place a scope in the uterine cavity and get a direct view rather than an indirect view. But since there are times when ultrasound does provide additional information—such as direct measurements–we simply place an ultrasound transducer on the abdomen—see below under Ultrasound Guided Hysteroscopy. Using this method we can offer the woman the best of both worlds—hysteroscopy and SIS.

Since hysteroscopy is done in our office-based surgical center we are able to offer sedation for women who choose it—something that is typically unavailable during a sonohysterogram (SIS) typically performed in an ultrasound suite!


Hysteroscopy is an excellent—relatively non-invasive tool—in assessing the inside of the uterine cavity. This is extremely important for women who are experiencing menstrual issues as well as infertility. Remember what I said earlier about fibroids being like “real estate”? Hysteroscopy is the most important test we turn to when we’re trying out to figure out the “location” and the “neighborhood” of fibroids that are primarily responsible for heavy vaginal bleeding or infertility.

Hysteroscopy allows us to look at the fibroid and determine how much of it lies within the uterine cavity. This simple test also allows us to determine the nature of the “attachment point”. These assessments are very important in order to determine how best to remove a fibroid. Certain fibroids are best approached through the “hysteroscopic” approach—meaning through the natural openings of the vagina and the cervix. Other fibroids are best approached laparoscopically—meaning through multiple small skin incisions that allow access to the abdominal cavity.

Importantly, hysteroscopy is also an important tool in differentiating fibroids from polyps. Polyps are also structures that may grow within the uterine cavity and are also responsible for abnormal menstruation.

Finally, there is an important and often neglected advantage of hysteroscopy. Hysteroscopy simulates the environment for removing fibroids. Although tests such as magnetic resonance imaging can supply a great deal of information about fibroids, hysteroscopy provides a direct look and feel. With hysteroscopy we can see the blood vessels feeding the fibroid, watch the attachment site and get an important idea about whether or not certain instrumentation can safely fit through the cervix in order to remove fibroids within the uterine cavity (submucous). No other test can provide this simulation.

Comparison of a normal uterus to one with Submucous Leiomyoma and one with Septum-Intrauterine Scarring.


I need to be clear about something. I am not suggesting that every woman who requires an investigation beyond a simple ultrasound requires both a hysteroscopy and an ultrasound. What I’m saying is this: if a woman has an abnormal ultrasound finding that needs to be further evaluated because of the suspicion of a fibroid or a polyp it makes sense that she undergo a hysteroscopy in a facility where an ultrasound can be simultaneously available. Many—but not all women–with abnormal ultrasound finding will require further evaluation with hysteroscopy. If this examination is done in a facility where ultrasound examinations available at the time of her hysteroscopy then a great deal of information can be gained in this single test. This includes:

  1. The size, number and grade of fibroids
  2. The size and number of endometrial polyps
  3. The type, size and location of the attachment points
  4. The nature of the blood supply to the fibroid
  5. Information about the cervix—which is critical toward formulating a plan for removal of the fibroid or polyp
  6. Additional information that will be useful to the surgeon who is contemplating removal of the fibroid and which is the superior route of removal.


If you read on-line articles you will find many scholarly articles on the benefits of magnetic resonance imaging (MRI) for fibroids. MRI is clearly a superior method for determining the size, location and number of fibroids. MRI is often worthwhile performing if the removal of fibroids are contemplated using a laparoscopic approach. It is also important if one is considering uterine artery embolization or focused ultrasound destruction of fibroids. However, MRI is generally quite unhelpful in determining whether or not a fibroid can be removed hysteroscopically – through the cervix and vagina. Keep in mind that MRIs are quite expensive and while they are very sensitive for detecting very small fibroids (less than 1 centimeter) these smaller fibroids are often of questionable clinical importance. The bottom line is this—the best tools for evaluating the kind of fibroids that produce excessive menstrual bleeding are clearly a combination of ultrasound and hysteroscopy.

A woman having an MRI performed to check for fibroids.

MRI may be the best tool, however, when evaluating a uterine containing numerous fibroids that require laparoscopic removal or procedures such as uterine artery embolization and focused ultrasound destruction.