How to Read an Ultrasound: Learn What Colors & Numbers Mean
An ultrasound is a medical imaging test that uses high-frequency sound waves to produce images of the inside of your body, such as organs, muscles and other soft tissues. The radiologist or ultrasound technician will then interpret the images and your doctor will communicate any findings with you at a later appointment.
While it is your doctor’s role to explain your report to you, PocketHealth allows you to securely access your results as soon as they are officially uploaded. This gives you an early look at your ultrasound data before your appointment.
Interpreting all the numbers, abbreviations and sometimes even colors in your report can be overwhelming. This guide will break down what they all mean, helping you better understand your results and prepare any questions for your upcoming appointment.
Your ultrasound report includes images from your scan, as well as the assessment made by the radiologist, ultrasound technician or other specialist. The report may contain technical medical terminology and other complex data. Some possible details in the report include:
Interpreting this information can be challenging for patients. While your provider will review these results with you at a later appointment, there are ways to prepare for this discussion. PocketHealth Report Reader offers easy-to-understand definitions of the medical terminology within your report, helping you better comprehend your results. This allows you to be more informed when your provider discusses them with you. Additionally, MyCare Navigator is a powerful tool to prepare you for your appointment. It suggests personalized questions to ask your doctor, maximizing your time together.
An image showing what different colors mean on an ultrasound
The ultrasound probe, also called a transducer, sends high-frequency sound waves into your body through a sound-conducting gel. The sound waves bounce off your internal structures, whether liquid, soft tissues or bone, and the ultrasound machine converts the collected sound waves into images in shades of black, white and gray. The intensity of the shade you see represents the density of the structure the sound wave encountered.
Black in an ultrasound image represents liquid, like amniotic fluid or a fluid-filled cyst. Most sound waves pass through fluid-filled areas, with only a small amount reflected back, making the area appear black.
White represents very dense structures like bone or kidney stones. Sound waves directed at bone easily reflect back, appearing bright white on the ultrasound image.
Gray in an ultrasound represents different types of tissue. The darker the gray, the denser the tissue, since only some of the sound waves are reflected back. Lumps or masses typically appear as dark gray spots on an ultrasound.
Red and blue colors on Doppler ultrasound for arterial and venous blood flow
Most ultrasound images are only black, white and gray. However, if you have a Doppler ultrasound, you may also see colors in your image. Colors are only seen in Doppler ultrasounds, which capture images of the direction and speed of blood flow in your vessels. Here’s a breakdown of what those colors mean:
Color on an ultrasound is not a negative aspect; it is a useful way to categorize features like blood circulation. Different colors indicate various vascular areas, helping the ultrasound technician understand what they’re observing.
In Doppler ultrasounds, red and blue colors have specific meanings. Blood flowing toward the transducer (arterial blood flow) appears in red, whereas blood flowing away from the probe (venous blood flow) appears in blue.
This means that arteries, carrying blood away from the heart, are displayed in red, while veins, which bring blood back to the heart, appear blue. Deviations from these color patterns may signal blood flow abnormalities and warrant additional investigation.
Yellow/orange are not usual Doppler colors. When yellow does appear, it is typically at the interface between red and blue. Yellow can suggest blood flow issues or turbulence, which is important for diagnosing blood vessel conditions and initiating appropriate intervention.
Most Doppler ultrasound systems don’t use the color green, unless they are particularly advanced. When green does appear, its meaning can vary depending on the machine’s parameters. It’s important to ask your doctor to help interpret this color, as the results will depend on the specific color map used. In some machines, green may represent one aspect of blood flow, while in others, it could have a completely different meaning. Color maps can differ from machine to machine.
Some possibilities for green include:
Now that you have a solid understanding of what your report shows, you can see how your ultrasound images support the radiologist’s findings.
Upon first glance of an ultrasound image, you’ll notice numbers and acronyms at the top of your ultrasound picture. These don’t have anything to do with the contents of your image. Instead, they’re used by the hospital or imaging clinic to identify each patient and record the ultrasound equipment settings used, along with any other hospital or clinic-specific information they collect. Additional data may include your name, the hospital reference number and other such identifying information.
Ultrasound image of a newborn’s right kidney in the sagittal plane. The information in the blue boxes is collected by the hospital or imaging clinic for administrative purposes only.
During your ultrasound, the technologist, sometimes called a sonographer, will adjust the ultrasound machine settings and probe angles to get the best image possible. Depending on your situation, you might even receive a contrast agent. Changing settings and angles provide different views, while the contrast agent improves the quality of your images. The following terms describe visual effects in your ultrasound images:
Attenuation is the reduction of signal intensity from the probe, producing a shadowy effect that makes the area look darker. This helps the radiologist clearly distinguish between different types of tissue.
Enhancement refers to the efforts made to improve ultrasound images.
Anisotropy is an image artifact, meaning a spot or feature in the ultrasound image that is introduced by accident and does not exist in the tissue being scanned. Such image artifacts disappear when the angle of the probe is changed.
The following tips will explain the basics of what to look for and what it means.
Before reviewing any images, it’s important to first examine the findings in your accompanying radiology report, when available.
While reviewing your report is typically done with your doctor at a follow-up appointment, you can also get early access to your imaging results through PocketHealth, often as soon as they are released by the hospital or imaging clinic. PocketHealth Report Reader can also help you understand complex medical definitions in your ultrasound report, so you are better prepared for a follow-up conversation with your doctor.
However, there’s no substitution for professional medical advice. Access to your imaging results does not replace reviewing those findings with your referring physician during a scheduled appointment. This is a critical step because your healthcare provider interprets the results along with other scans or your overall medical history.
This is possibly the most challenging aspect of reading an ultrasound since it’s not always clear what exactly you’re looking at. Ultrasound images appear in gradients of black and white which can be tough to distinguish, and certain organs or body parts can be easily mistaken for others.
It’s important to remember that with most ultrasounds (excluding transvaginal ultrasounds), you are looking at a mirror image. In other words, the left side of the image shows the left side of the body part, and the right side of the image shows the right side of the body part.
Most ultrasound images have a cone-like shape: the narrowest end of the cone is the top of the image, where the ultrasound probe was first placed on the body. Start your review there. Much of the topmost section will be gray, representing layers of tissue. Below, where the image widens out into a fan shape, is the area of the body that the ultrasound was scanning for—and the reason you had the appointment in the first place.
As covered earlier, it’s important to remember that different colors represent various aspects of an ultrasound. Black areas in your images indicate fluid, while tissue appears gray. The brighter the gray tone, the denser the tissue. The brightest white represents bone. Keep these distinctions in mind as you review your images to differentiate between tissue, bony structures and fluid-filled areas. For Doppler ultrasounds, refer to the color meanings discussed earlier in this guide.
Many parents and family members are excited to examine pregnancy ultrasound images and check the progress of the baby’s development. All the above tips still apply, but there are also a few additional things to look for in your fetal ultrasound image.
The uterus will be a clear, dark, pear-shaped section in the ultrasound image. What you can see in a pregnancy ultrasound will depend on how far along you are in your pregnancy. For instance, you might see the yolk sac in early pregnancy ultrasounds, but it is gradually absorbed by the embryo and disappears before the second trimester.
Ultrasound image at 7 weeks pregnant shows the embryo and the amniotic, gestational and yolk sacs within the uterus.
Since ultrasounds use sound waves instead of radiation to create images, they are widely used to monitor fetal growth and progress, as well as measure gestational age and confirm if there’s sufficient amniotic fluid. The development of the fetus will change dramatically during each trimester of pregnancy.
Ultrasound image of a fetus at 11 weeks pregnant (first trimester).
In a pregnancy ultrasound image, you’ll see letters and numbers, typically listed down the side or along the bottom of the image. These are the fetal biometric measurements recorded by the ultrasound technician to assess fetal development. Here’s a list of some of the most common measurements:
There may also be other fetal measurements taken to identify abnormalities during certain weeks of pregnancy. For example, the Nuchal Translucency measurement (NT) is taken late in the first trimester and measures the amount of fluid behind the embryo’s neck to assess the risk of chromosomal abnormalities like Down syndrome.
A pregnant person looking at their pregnancy ultrasound report on PocketHealth
Typically, it takes less than a week for your referring physician to receive your ultrasound results. As with other medical imaging procedures like X-rays and CT scans, the technician forwards your ultrasound images to the radiologist.
The radiologist will interpret the images and send them and an accompanying ultrasound report to your referring physician. Then your doctor will discuss the results with you in a follow-up appointment.
The exact timing depends on several factors, including the complexity of your ultrasound, the schedule at the imaging clinic or hospital or the need to have further imaging to clarify your results.
Ultrasound reports are full of complicated medical interpretations and terminology. PocketHealth Report Reader provides easy-to-understand definitions for complex medical terms so that you can be more informed.
MyCare Navigator highlights any follow-up recommendations your report might contain and provides personalized questions to ask your doctor so that you can have more thorough conversations at your follow-up appointment.
The more you understand, the more focused and confident you can be in conversations with your healthcare team and the better you can advocate for your health going forward.
Updated: May 10, 2025
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