Ultrasound Tests: Purpose, Preparation, Procedure, Types, Advantages and Follow-up

Ultrasound is also called as sonography. It uses high-frequency sound waves to produce ultrasound images of what is going on inside the body.

Updated: October 28, 2019


Ultrasound is also called as sonography. It uses high-frequency sound waves to produce ultrasound images of what is going on inside the body. Fetal imaging is one of the most common uses of ultrasounds. However, this diagnostic tool actually has many applications in finding out problems with organs, vessels, and tissues without needing to make an incision. As this method does not use radiation it is the preferred method for viewing a developing fetus during pregnancy.

Purpose of Ultrasound Tests:

Generally ultrasound scans are done in pregnancy to provide the first view of her unborn child to an expectant mother. However, the test has many other uses. An ultrasound may also be done if you are having pain, swelling, or other symptoms that require an internal view of your organs. An ultrasound can provide a view of the

  • bladder
  • brain (in infants)
  • eyes
  • gallbladder
  • heart
  • kidneys
  • liver
  • ovaries
  • pancreas
  • spleen
  • thyroid
  • testicles
  • uterus
  • blood vessels

But there are also some diagnostic limitations of ultrasound. The sound waves do not transmit well through dense bone or parts of the body that may hold air or gas, such as the bowel.
Ultrasound images have many uses during pregnancy. They may be used to

  • determine due dates, reveal the presence of twins or other multiples, and rule out ectopic pregnancies in early stage.
  • detect potential problems, including some birth defects, placental issues, breech positioning, and others.
  • estimate how large a baby is just before delivery in later pregnancy.
  • look for the sex of the babies via ultrasound midway through a pregnancy.

Ultrasound imaging can help guide surgeons' movements during certain medical procedures such as needle biopsies, which require the surgeon to remove tissue from a very precise area inside the body for testing in a lab. Sometimes these are also used to detect and treat soft-tissue injuries.

Preparation for an Ultrasound:

Depending on the type of ultrasound test you are having you will need to take the below steps to prepare for an ultrasound. Fasting for eight to 12 hours before your ultrasound is required, especially if your abdomen is being examined. Undigested food can block the sound waves, making it difficult to get a clear picture for the technician.
For an examination of the gallbladder, liver, pancreas, or spleen, you need to eat a fat-free meal the evening before your test and then to fast until the procedure. However, you can drink water and take any medications as instructed by your doctor.
For some of the examination, you need to drink several glasses of water in the time leading up to the test and hold your urine to ensure that your bladder is full to get better visualized images.
Make sure to inform your doctor about any prescription drugs, over-the-counter medications, or herbal supplements that you take before the examination. An ultrasound carries minimal risks. Unlike X-rays or CT scans, radiation is not used in ultrasounds. For this reason, they are the preferred method for examining a developing fetus during pregnancy.

Procedure for an Ultrasound:

You should wear comfortable clothing that is easy to remove or partially remove if required. In some cases, you may need to take off your clothes or wear a gown.
But often the area of the body that is being screened can easily access by the ultrasound technician without taking off your clothes.
A water-based gel will be applied to the area by the technician so that the transducer can easily glide across your skin without any air in between. The gel also helps transmit the sound waves. Presence of any specific markers will be noticed and measurements will be taken while the test is in progress.
A typical ultrasound takes between 30 minutes to one hour. Usually you won't feel any kind of discomfort during the test, and you are awake and alert during the procedure. Often a technician will discuss what he or she is seeing during the test, but in some instances, you may need to wait to discuss the findings with your doctor.
An instrument called a transducer which looks similar to a microphone emits high-frequency sound which will not audible to human ears. The waves echo as they hit a dense object, such as an organ or bone. It then records the echoes 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 usually perform the test who have special training in the technique.
You may need to change positions depending on the area being examined,so that the technician can have better access.
A radiologist or your doctor can interpret the ultrasound images. This technology can help diagnose and treat certain conditions. The gel will be cleaned off of your skin after the procedure and you can get back to your normal activities.

Types of Ultrasound:

Most ultrasounds are done using a transducer on the surface of the skin. But sometimes, a special transducer is inserted into one of the natural openings of body to get a better diagnostic image. These include:

  • A transducer wand is placed in vagina of a woman to get better images of her uterus and ovaries in a transvaginal ultrasound.
  • A transrectal ultrasound is sometimes used in the diagnosis of prostate conditions.
  • The transducer probe is used in the esophagus so that the sonographer can obtain clearer images of the heart in a transesophageal echocardiogram.

Ultrasound can also produce different types of imaging. These include:

  • Doppler is a special type of ultrasound that creates images of blood flow through vessels.
  • Echocardiograms are used to view the heart.
  • Bone sonography helps doctors diagnose osteoporosis.
  • 3D imaging adds another dimension to the ultrasound image. These can create three-dimensional interpretations rather than the flat two-dimensional images that are made with traditional ultrasound.
  • 4D ultrasounds show 3D images in motion.

Advantages of Ultrasound:

  • Ultrasound captures images of soft tissues that don't show up well on X-rays.
  • Ultrasounds are widely accessible and less expensive than other methods.
  • The method is generally painless and do not require needles, injections, or incisions.
  • As the patient is not exposed to ionizing radiation, the procedure is safer than other diagnostic techniques such as X-rays and CT scans.

Follow-up After an Ultrasound:

Your doctor will review the images and check for any abnormalities after the examination. The findings will be discussed with you. If your doctor is able to make a diagnosis of your condition based on your ultrasound, they may begin your treatment immediately. Else, you may need to undergo other diagnostic techniques, such as a CT scan, MRI, or a biopsy sample of tissue depending on the area examined, if any abnormality is found and can not get diagnosed with the result of ultrasound alone.


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