Many people who hear the term "ultrasound" likely picture a pregnant woman in their doctor's office getting a sneak peek of the baby growing inside her womb -- perhaps even finding out whether they should paint the nursery pink or blue. But while fetal imaging is one of the most common uses of ultrasounds, this diagnostic tool actually has many applications.
Ultrasound, also called sonography, uses sound waves to develop ultrasound images of what's going on inside the body. An instrument called a transducer emits high-frequency sound, inaudible to human ears, and then records the echoes as the sound waves bounce back to determine the size, shape, and consistency of soft tissues and organs.
This information is relayed in real time to produce images on a computer screen. Ultrasound technicians, or sonographers, have special training in how to perform the test. Then a radiologist or your doctor will interpret the ultrasound images. This technology can help diagnose and treat certain conditions.
Ultrasound imaging has many uses in medicine, from confirming and dating a pregnancy to diagnosing certain conditions and guiding doctors through precise medical procedures.
Pregnancy. Ultrasound images have many uses during pregnancy. Early on, they may be used to determine due dates, reveal the presence of twins or other multiples, and rule out ectopic pregnancies. They also are valuable screening tools in helping to detect potential problems, including some birth defects, placental issues, breech positioning, and others. Many expectant parents look forward to learning the sex of their babies via ultrasound midway through a pregnancy. And later in pregnancy, doctors can even use ultrasounds to estimate how large a baby is just before delivery.
Diagnostics. Doctors employ ultrasound imaging in diagnosing a wide variety of conditions affecting the organs and soft tissues of the body, including the heart and blood vessels, liver, gallbladder, spleen, pancreas, kidneys, bladder, uterus, ovaries, eyes, thyroid, and testicles. Ultrasounds do have some diagnostic limitations, however; sound waves do not transmit well through dense bone or parts of the body that may hold air or gas, such as the bowel.
Use during medical procedures. Ultrasound imaging can help doctors during procedures such as needle biopsies, which require the doctor to remove tissue from a very precise area inside the body for testing in a lab.
Therapeutic applications. Ultrasounds sometimes are used to detect and treat soft-tissue injuries.
Most ultrasounds are done using a transducer on the surface of the skin. Sometimes, however, doctors and technicians can get a better diagnostic image by inserting a special transducer into one of the body's natural openings:
Additionally, ultrasound technology has advanced to allow for different types of imaging:
Ultrasounds offer many advantages:
Depending on the type of ultrasound test you are having, your doctor may offer special instructions, such as not eating or drinking anything for a number of hours before the test. Or you may be advised to drink several glasses of water in the time leading up to the test and refrain from using the bathroom to ensure that your bladder is full.
You should wear comfortable clothing that is easy to remove or partially remove. In some cases, you may need to disrobe or wear a gown, but often an ultrasound technician can easily access the area of the body that is being screened without your having to take off your clothes.
The technician will apply a water-based gel to the area. This is so the transducer can easily glide across your skin without any air in between. They may be looking for specific markers and may make measurements or notes while the test is in progress.
A typical ultrasound takes between 30 minutes and an hour. Ultrasounds usually are not uncomfortable, and you are awake and alert during the procedure. Often a technician will discuss what they are seeing during the test, but in some instances, you may need to wait to discuss the findings with your doctor.