How to Read an Ultrasound: Text, Images, and Colors

If you are a doctor or radiologist, part of your training was on how to read an ultrasound, which makes it easy. For patients, however, an ultrasound can look like a complex puzzle of tiny pieces that are hard to figure out.

Should we give up? Certainly not!

Reading an ultrasound can be easy if you know what meaning to assign to the text and numbers, images, and colors on an ultrasound. And that’s what we’ll help you do in this article.
But first things first. Let’s begin with a quick recap of the meaning of what you’ll be reading: an ultrasound.

An ultrasound, also called a sonogram, is an image of internal body structures produced by sound waves when a radiologist places an ultrasound scanner probe on the skin over the designated body area.

These images can show information about the status of body structures, such as a fetus in a normal position inside the uterus.

However, they can also show abnormal body structures and tissues, such as tumors, providing key details for medical diagnosis and treatment.

One of the most common ultrasounds that radiologists and doctors perform is the fetal ultrasound on pregnant women.

In this article, we shall refer to fetal ultrasound when explaining how to read an ultrasound. Also, expect a quick mention of what breast cancer looks like on ultrasound along the way.
And now that we know what it is, we can proceed with how to read a sonogram.

Ultrasound reading entails giving meaning to the details in the ultrasound photo. These details include text and numbers, images, and colors in different shades.
Focusing on these three types of details, I put together this 3-step guide to reading an ultrasound.

The tiny scripts on an ultrasound image can be intimidating, just like other medical inscriptions. For that reason, most people will tell you to ignore the writings, and they are right to some extent.

You don’t need to fret trying to understand every word on an ultrasound image. The only information that may interest you is the name that shows the ultrasound imaging was done on you.

Other details you can easily decode include the date and a medical reference number.

Leave the other less decipherable writings on the ultrasound to doctors and sonographers. Often, these are ultrasound machine interpretations of the settings and instructions the sonographer feeds to the ultrasound machine during imaging.

The orientation of the ultrasound is important in order to understand what you see on the screen or printed ultrasound picture.

When the radiologist or doctor performs the ultrasound, s/he first checks the probe to identify the indicator. As a standard rule, the indicator should face the patient’s right when the probe is transverse and point to the patient’s head in a longitudinal orientation.（1）

So, to read the image, imagine the patient lying supine (on their back, face up) on the examination bed. The radiologist places the probe on the patient’s abdomen in a transverse orientation.

So, here’s what you’ll see on the screen or the printed version of the ultrasound:

We know ultrasound pictures as black and white. Sometimes, however, you will notice gray shades and red and blue colors.

So, what do the colors on an ultrasound photo mean?

To understand the colors of an ultrasound, it is crucial to appreciate first how these colors come about.

When the sonographer places the probe on your skin and presses the scan button, the probe sends high-frequency sound waves (2-10kHz) through body tissues to the targeted body structure.

Once the sound waves hit the body tissues, they are reflected back, and the probe receiver detects them as sound echoes. This is why the ultrasound is sometimes called echography. The echo sounds then appear as images on the ultrasound monitor.

Not all body tissues react in the same way to ultrasound waves. Some tissues bounce back an echo from ultrasound waves more readily than others. Experts call this ability of body tissues to return an echo signal when hit by sound waves echogenicity.（3）

So, it is a tissue’s echogenicity that determines what color it returns on the ultrasound image:

We can use this info on ultrasound colors to give an example of what breast cancer looks like on ultrasound.

If you have a fluid-filled cyst in your breast, it will show as black circles on ultrasound (remember that fluid is anechoic and, therefore, black).

Cancerous tissues are hypoechoic. So, if you have a cancerous tumor in your breast, it will present in a gray shade, but darker than the surrounding normal hypoechoic tissues. （4）Always remember that the oncologist is the best interpreter of a breast cancer ultrasound.

Back to ultrasound color interpretation.
With advanced imaging technology, today’s ultrasounds can also show other colors. This usually happens through the color Doppler imaging technique.（5）

In ultrasound imaging, color Doppler produces color codes of tissue speed and flow direction over gray images to show blood movement in veins and arteries. As a diagnostic tool, the color codes can help detect blood clots, narrowed arteries, or other blood-flow-related medical issues.
On a normal ultrasound, however, the red and blue colors reflect the direction of blood flow to or away from the ultrasound probe. Some healthcare practitioners use the BART mnemonic code to remember that:

If you’ve understood these 3 steps of how to read ultrasound, we can now proceed to an actual example of how to read pregnancy ultrasounds.

I mentioned earlier in the article that pregnancy or fetal ultrasounds are very common. That’s because expectant women and their partners love to follow the healthy development of their baby growing in the womb.

However, pregnancy ultrasounds don't just tell the baby's developmental progress. They also reveal other details of the pregnancy, depending on the stage of gestation.

Here’s a tabled summary of what a fetal ultrasound can show at different stages of the pregnancy.

In all three stages, the ultrasound will also show the position of the embryo/fetus and detect the baby’s heartbeat and rate.

Fetal body tissues develop gradually and can produce different levels of echo signals at different stages of the pregnancy. As such, a fetal ultrasound will return different color shades depending on fetal age.

That said, we can use the general steps of how to read an ultrasound that we explained above to read a pregnancy ultrasound in these steps:

We exemplified earlier that the top of a uterus is concave due to the probe placement on your abdomen.

From there, you will see two white lines that mark the edge of the womb downwards on either side. Note that these lines may be absent if the radiologist focuses only on the center of the uterus and not its entire structure.

Within the womb of a pregnant woman, an ultrasound will show a large dark circle that marks the amniotic fluid. This is the space where the baby will grow over the pregnancy months.

In the first trimester, the embryo will present as a tiny grey or whitish spot inside the amniotic fluid.

Along the pregnancy period, you can tell other features of the fetus with gray and whitish shades, including the head and your baby’s skeletal system when it’s better formed in the last part of the first trimester.（6）

One of the reasons a pregnant woman will want an ultrasound is to know the sex of the baby. While determining the sex can be elusive at the beginning, an ultrasound will show signs of your baby’s sex towards the end of the first trimester/beginning of the second trimester.

Radiologists focus the ultrasound probe on the fetus’ genital area using the tubercle, a nub situated between the legs.

If you want to know more about your baby on an ultrasound, you can opt for 3D/4D ultrasound imaging. With this, you can see your baby’s facial features in clear gray and white shades with 3D images or a 4D video.

Finer fetal details are captured best by ultrasound after week 20, and medics can use this type of ultrasound to detect fetal defects such as a cleft lip/palate.(8)

Most of us will be at a loss when wondering how to read an ultrasound. But you don’t have to feel lost.
The writings on an ultrasound photo are only important for your personal details. The ‘left is right’ rule will help you know which part of the image shows which part of your body. The different colors point to how well a body tissue reflects back the ultrasound waves sent by the probe.
If the details on how to read a sonogram in this article should still sound Greek, you know you can count on your doctor or urologist to read for you the ultrasound with precision.

1. MSD Manual Professional Version. How To Do Ultrasonography.

2. McGraw Hill. Chapter 3. Ultrasound Orientation.

3. National Breast Cancer Foundation. Breast Cancer Ultrasound.

4. Evans DH, Jensen JA, Nielsen MB. Ultrasonic colour Doppler imaging. Interface Focus. 2011 Aug 6;1(4):490-502.

5. Gharekhanloo F. The ultrasound identification of fetal gender at the gestational age of 11-12 weeks. J Family Med Prim Care. 2018 Jan-Feb;7(1):210-212.

6.Divya K, Iyapparaja P, Raghavan A, Diwakar MP. Accuracy of Prenatal Ultrasound Scans for Screening Cleft Lip and Palate: A Systematic Review. J Med Ultrasound. 2022 Aug 16;30(3):169-175.