Sonography & Sonohysterography of the Non-Gravid Uterus

Ultrasound in Postmenopausal Bleeding and Biopsy Guidance

And secondly, can ultrasound help if a woman is gonna have a biopsy for postmenopausal bleeding because of the concern for cancer?

Can ultrasound help identify the appropriate biopsy technique?

To answer those questions, let's start by considering what are the ultrasound features of the endometrium and how do they relate to endometrial pathology?

Ultrasound Features of Endometrial Pathology

Well, with endometrial atrophy, the ultrasound feature is uniformly thin endometrium with an endometrial polyp.

The ultrasound appearance is a focal area of thickening, often with a feeding vessel seen on colored doppler.

Occasionally there are cystic spaces, and if there's fluid in the uterine cavity with a polyp, there will be projection of tissue into the fluid filled cavity with endometrial hyperplasia.

The ultrasound appearance is a homogeneously thickened endometrium with endometrial carcinoma.

Typical appearance is a heterogeneous endometrium with unclear margin or markedly thickened endometrium.

And with a submucosal fibroid, you'll see a hypo coic lesion indenting the endometrium.

Examples of Ultrasound Appearances

And here are a few examples.

This is a typical appearance of endometrial atrophy postmenopausally.

You can see a very thin line of the endometrium measuring about 1.6 millimeters, measuring 1.6 millimeters, 0.16 centimeters.

This is an example of a polyp.

You can see a focal echogenic lesion in the center of the uterus.

There is one feeding vessel into it.

Very typical appearance of a polyp.

This is an example of endometrial hyperplasia.

You have a thickened endometrium, very prominent endometrium, but it's very homogeneous and well defined margins.

This is an example of endometrial cancer, very thickened, extremely thickened, and very poor margins.

In some places, it's somewhat heterogeneous, darker area here, brighter area here, and a very unclear margin down posteriorly at that point.

Another example of cancer where the endometrium is extremely thick, but it also has fluid in the uterine cavity.

And a irregular endometrial surface outlined by that fluid.

Also seen to be irregular here.

Limitations of Ultrasound Features for Diagnosis

So as we've seen on the previous few slides, there are some ultrasound features that are typical for various kinds of endometrial pathology.

However, they're not, in most cases predictive enough to be able to make a clear or definitive diagnosis.

In fact, I think it's fair to state the following that in a woman with post-menopausal bleeding, the only sonographic feature that's definitive enough to eliminate the need to perform a biopsy is endometrial thickness.

Measuring Endometrial Thickness

Since endometrial thickness is used or can be used to say biopsy is not necessary, and we'll see in a minute, we have to have a very careful technique when we are measuring the endometrium.

So we want to measure it via a sagittal image on a transvaginal ultrasound, transvaginal in a woman with postmenopausal bleeding to get the best definition of the endometrium to measure it, we take a double thickness measurement, including the anterior and posterior endometrium.

Usually you can't separate them, but if there is fluid in the endometrial cavity or in the uterine cavity, you have to measure the anterior and posterior components separately and add them together to get the endometrial thickness measurements.

We wanna sweep through the uterus to find the area of maximal thickness.

And if you don't see the endometrium well enough to get an accurate measurement in a woman with postmenopausal bleeding, it's important to interpret the scan as being non-diagnostic.

As far as endometrial thickness goes, if you can't see the endometrium clearly in its entirety, and this is how you measure it, criteria are put forth by an international endometrial tumor analysis group in 2010.

You wanna pick the region of maximal thickness as in this diagram, and if there's fluid in the cavity, separating the anterior and posterior portions, you wanna measure each separately and add them together.

Here is a good example of why you wanna look at the area of maximal thickness.

Initially you might think that you were measuring an endometrium here, and it looks like it's just about four millimeters.

However, what you can see when we sweep through, as in this image here and stop at the area of maximal thickness, it's not four millimeters, it's 8.7 millimeters, which is, as we'll see soon, abnormally thick.

So again, it's important to sweep through, pick the area of maximal thickness and measure there.

When there's fluid in the cavity, you can see a little thin band of fluid.

The right way to measure it is to measure the anterior part and the posterior part.

You can see two measurements here.

We add them together to determine a endometrial thickness here of 4.8 millimeters.

Incorrect would be to measure the whole thing, even though there's fluid in the middle.

And you would, if you do that, get an incorrect measurement of 6.5 millimeters as seen here.

So when there's fluid measure, anterior and posterior parts separately.

Clinical Significance of Endometrial Thickness

So what's so important about the endometrial thickness?

A number of studies, a fairly large number of studies have looked at the relationship between endometrial thickness and endometrial cancer.

In particular, they have looked at what the diagnosis is in a patient with a thin endometrium.

What do we mean by a thin endometrium?

Well, there's a little bit of variability in these studies, but typically using either four or five millimeters as the definition as the cutoff for a thin endometrium.

And I highlight in green these two columns.

They're the ones that we wanna focus on.

So the first column, this one, endometrial cancer looks at what is the likelihood or what is the incidence of endometrial cancer in a woman with postmenopausal bleeding who has a thin endometrium?

And you can see it's exceptionally low.

It's very, very low.

In fact, in most studies, no one 0% of women with postmenopausal bleeding had cancer if their endometrium is thin.

So a thin endometrium comes pretty close to ruling out uterine and endometrial cancer.

What was the diagnosis?

It was almost always atrophy.

The vast majority of patients with a thin endometrium have endometrial atrophy.

Not all of them, but the large majority.

And in some studies, all patients with a thin endometrium had atrophy.

In other words, a thin endometrium.

According to one consensus conference, the Society of Radiologists and Ultrasound Consensus Conference called it thin if it was less than or equal to five millimeters.

The American College of O-B-G-Y-N Committee said it's thin if it's less than or equal to four millimeters.

In fact, in my own department, what we do is we say if the endometrium is four millimeters or less, it is normal thin in a woman with postmenopausal bleeding.

If it's four to five millimeters, it's borderline.

And if it's above five, it is thick.

So a thin endometrium indicates an extremely low false negative rate for endometrial cancer.

In other words, the likelihood of endometrial cancer in a woman with postmenopausal bleeding and a thin endometrium is somewhere between zero and 2% very low.

The false negative rate of zero to 2% is actually lower than the false negative rate of an endometrial biopsy.

So a thin endometrium means an extremely low likelihood of endometrial cancer.

It also means a very high likelihood of endometrial atrophy, above 90% in most studies.

So if this is a woman with postmenopausal bleeding, we measure the endometrium looks thin.

It is thin, it's just over one millimeter.

This is a thin endometrium and a woman with postmenopausal bleeding, which means by those studies that she has a very high likelihood of endometrial atrophy and extremely low likelihood of endometrial cancer.

So biopsy is unnecessary because of the low likelihood of endometrial cancer.