What Is a Sonogram?

What is a sonogram? Image is a sonogram of a four month old fetus

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what is a sonogram. sonogram example

Dr. McCoy whips out his trusty tricorder and waves it over his patient. As if by magic, a three-dimensional image of the organs and muscles and circulatory system appear on the screen. With this information in hand, Bones can see that the five-month-old fetus is doing just fine. Yes, it sounds like science fiction. But have you ever wondered, “What is a sonogram?”

If you have, you don’t know how close we are to making science fiction into science reality.

Sonogram? Ultrasound? Same Thing, Right?


what is a sonogram. sonogram example

CC BY-SA 2.0, Rick Kimpel via https://www.flickr.com


what is a sonogram. lady having ultrasound


CC0 Creative Commons, MedicalPrudens via https://pixabay.com

Well, no. Not exactly. We tend to use the words interchangeably because most people don’t really know how the process works. What is an ultrasound? What is a sonogram? The super basic version is this: An ultrasound is a procedure, a sonogram is a result.

Here’s the less basic version.

What is an ultrasound?

When you get an ultrasound, the technician blasts your body with intense high-frequency sound (that’s where the “ultra” in “ultrasound” comes from).

OK, it’s not nearly as scary as I just made it sound. There’s no more risk than standing next to a loud radio. Less risk, actually, because it can’t damage your hearing or make you start humming an annoying tune you can’t get out of your head!

Much like how a bat or a dolphin gets around by echolocation, the sound waves bounce off of your innards. The reflected sound is captured by the ultrasound machine (the handheld wand is the most familiar capture device, but there are variations). The machine than renders the sound into an image.

That’s the answer to the question, “What is an ultrasound?”

The Different Types of Ultrasound

The majority of ultrasounds are done using a transducer on the surface of the skin. Sometimes, a better diagnostic image can be made with the insertion of a special transducer into one of the body’s natural openings. Below are some examples of this:

  • Transrectal Ultrasound – This is sometimes used in the diagnosis of prostate conditions. It involves using a transducer wand that is placed inside the rectum.
  • Transvaginal Ultrasound – This process uses a transducer wand that is placed inside the woman’s vagina to get images of the ovaries and uterus.
  • Transesophageal Echocardiogram – This uses a transducer probe within the esophagus to receive images of the heart.

What is an Ultrasound Used For?

The ultrasound is best known for confirming and monitoring pregnancies, however, an ultrasound is also commonly used for the following:


Doctors use ultrasound imaging to help diagnose a number of conditions that affect the bodily organs and soft tissues. These include:

  • Liver
  • Heart
  • Abdomen
  • Kidneys
  • Spleen
  • Gallbladder
  • Blood Vessels
  • Bladder
  • Thyroid
  • Pancreas
  • Breast
  • Testicles
  • Ovaries
  • Eyes

There are a small number of limitations for ultrasounds. For example, the sound waves will not transmit well through areas of the body that may hold gas or air (such as the intestines), or through areas that are blocked by dense bone.

Medical Procedures

When a doctor needs to remove tissue from a particularly precise area of the body, ultrasound imaging can assist in visual direction.

Therapeutic Application

An ultrasound is sometimes used for the detection and treatment of some soft-tissue injuries.

What is a sonogram?

The next question is, “What is a sonogram?”

That would be the image produced by the ultrasound! Sonogram more or less translates into “sound writing” (like “sonar” and “telegram” mashed together). Whether it be the image on a screen or a print out of your unborn baby taped to your desk, both are sonograms.

Figuring out what you’re looking at it is not always easy, though. X-rays of bones are pretty straightforward: the hip bone is connected to the thigh bone. The thigh bone is connected to the…well; you know the song.

Sonograms are a bit trickier.

For instance, liquids don’t block the sound waves, so they appear black on the sonogram. Soft tissue like skin and muscle appear as grays while hard tissues like bones and teeth are solid colors. And the fact that it’s two-dimensional means you have to have a pretty decent knowledge of human anatomy to know what you’re looking at.

Sure, everyone knows what a cross-section of a skull looks like but what about the liver or a kidney? Most of us wouldn’t even know what one looks like if it was sitting on a plate in front of us!

Still, for a trained ultrasound technician, sonograms are windows into the human body unlike anything else. So where did this awesome technology come from?

A (Very) Brief History of Peeking Under the Hood

While Dr. Karl Dussik of Austria is credited with being the first person to use ultrasound to try to detect tumors, Dr. George Ludwig in the United States was the first to make a practical use of ultrasound to detect gallstones in 1948. Over the next decade, other doctors refined the procedure to detect breast tumors and to perform echocardiograms. But the real breakthrough came in 1958 when Dr. Ian Donald used an ultrasound to take a sonogram of a fourteen-week old fetus.

Interest in the procedure and the equipment exploded, spurring an astonishing rate of development. By the early 1970s, ultrasound technology was in widespread use all around the world. It’s hard to overstate the number of lives saved since then.

So what is a sonogram used for and how does it save lives?

Using it for babies

The human body is a wondrous machine. It’s also prone to making mistakes. A lot of them.

These mistakes can be deadly for the tiny little bundle growing inside the mother, as well as for the mother herself. Before sonograms, there wasn’t a darn thing we could do about it until the baby was born (or disaster struck) because there was simply no way to know if there was a problem. Now we can assess if the pregnancy is proceeding normally or if any steps need to be taken to help it along.

In the worst case scenarios such as an ectopic pregnancy where the nonviable fetus is growing outside the womb, a sonogram can alert the doctor early enough to save the mother’s life.

Sonograms can also detect a ripped placenta requiring stitches. Or if there’s too much or too little amniotic fluid, conditions that require very different treatments. In the best case scenario, a sonogram will tell us that everything is just fine.

For an expecting couple, having that kind of reassurance provides a much needed psychological buffer from the stress of pregnancy. As someone that’s lived through two miscarriages, seeing a healthy fetus on the screen in the second trimester felt like having a boulder taken off of my back.

Secret parenting tip!

Here’s a super nifty thing you don’t hear about because doctors don’t do it very often. As you may or may not be aware, after a baby is born, it takes a few years for the bones of your baby’s skull to fuse together. That’s the little soft spot on the top of their head.

Normally, the bone would block the sound waves. But because there’s essentially a “hole” in your child’s skull, you can get a sonogram of their brain. My son had one done because his head was enormous and they were worried about water on the brain. It turns out that he just had a really large head, but the sonogram was amazing. It was literally a picture of his brain, with all the squiggles and curves!

Sonograms for other stuff

Lest you think sonograms are only for adorable baby pictures, let me assure you that this is not so! There’s actually a fairly lengthy list of ways this technology is used in medicine, so here’s a brief rundown:

  • Anesthesiology — When they want to stick a needle near a nerve cluster, they need to see how to avoid it.
  • Cardiology — This lets them see if your heart is leaking more than normal (yes, your heart leaks, look it up).
  • Tumors — These are a lot easier to spot in 3D, but even regular sonograms are great for this.
  • Musculoskeletal — X-rays are great for broken bones. Not so good for torn muscles, tendons, nerves, and the rest.
  • Angiology — Clogged arteries? Blood flow all messed up? This is one they can take a look at where the problem is.

3D/4D Sonograms

One of the cooler innovations in recent years has been three-dimensional sonograms. Just like Dr. McCoy! By three dimensional, I don’t mean 3D like you see in the movie theaters. Rather, the image is no longer a two-dimensional slice of whatever it is you’re looking at. So instead of a cross-section of a baby’s face or that liver or kidney from before, you can see the entire thing on the screen like a regular photo.

Granted, it’s a computer-generated image, and it’s not even remotely as sharp as even the lowest of low-resolution phone cameras, but it’s still an invaluable tool for diagnosing problems without having to cut open the patient.

Even better, thanks to increasing processing power, the three-dimensional images are being rendered in real time. These are “4D” sonograms (time is the fourth dimension for you non-science fiction types out there).

What is a sonogram in real time 3D good for? It only lets doctors stick tiny probes into patients and maneuver it on the screen as if they were operating on the exposed interior of the body. You get all of the surgery without all of the trauma. If that’s not science fiction, I don’t know what is!

The Future

Three words: Smaller. Faster. Better. There are already portable ultrasound machines that you can wear as a vest (say, on a battlefield).

There’s even a version that can run on a smartphone! As computers continue to become more powerful, the processors will be able to render even more detailed images, making the images of just five years ago look like caveman drawings in comparison. This will be especially useful for 4D imaging, which is processor intensive but incredibly valuable as a tool for doctors.

At the same time, manufacturers are experimenting with HIFU, High Intensity Focused Ultrasound. They target and destroy tumors inside the body without having to cut the patient open. The future is sounding pretty great. Not that you can actually hear it…

So what is a sonogram? A simple concept from nature turned into a hi-tech weapon against disease and injury.

As the technology improves, it will continue to become even more widespread. That means demand for people trained in its use will grow as well. If you’re looking for a field to enter, this might just be the one for you. You may not be Dr. McCoy with a tricorder flying through space, but you’ll be the next best thing!

Feature image: CC0, by CDC/Jim Gathany, via Wikimedia

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