How to Read an Ultrasound Image

To the untrained eye, an image from an ultrasound looks like a Rorschach puzzle, open for interpretation. “Ultrasound” and “sonogram” are two words that many people confuse and use interchangeably. They are related but still very different. An ultrasound is the examination and the act of using soundwaves to create an image. The image the ultrasound creates is the sonogram. Knowing how to read an ultrasound picture, or sonogram, takes some practice and knowledge of the human anatomy, but it is possible for the average person.


Pay no mind to the numbers and text at the top of the image. Hospitals use them internally to identify the patient, the hospital reference number, or the ultrasound machine identifier. The information doesn’t have anything to do with the image you are viewing, so you can ignore it.


Most sonograms are in black and white. Advances in imaging like 3D and 4D imaging have led to changes in images so that some are now yellow in color. They are all monochromatic, though, existing in only one color and shades of it. Sound waves from the probe penetrate the skin, bounce off structures, and return to the probe and CPU. The computer then translates the data and produces an image. The sound waves cannot penetrate bone, so in a sonogram, any bone shows bright white. The more that the waves can penetrate something, the darker it appears on the image. Amniotic fluid and blood, for instance, look black on a sonogram. Tissue appears in shades of gray because the sound waves can penetrate somewhat but not as much as it does a liquid.


One of the biggest questions people have is, “What am I looking at?” They don’t know how the image is oriented or which way is up. Start at the top of the image, and work down. The very top is where the probe rests, so the image shows what the organs and fetus look like from the side, not the top. In an ultrasound of a uterus, what you see at the top is the outline of tissues above the uterus. Further down the image, you can see deeper into the uterus and the lining.


Depending on what the sonographer is examining, there are telltale signs that provide them with information. A knowledge of human anatomy comes into play for interpreting the structures. To determine the sex of a baby in the womb, there are specific shapes and structures they use to determine what the sex is. Experienced sonographers who know how to read an ultrasound picture can identify these structures to help patients read the sonogram.