Definition and Overview

Ultrasound, when used in a medical environment is also referred to as ultrasonography or sonography. It is an imaging method commonly used to diagnose a variety of medical conditions and diseases. An ultrasound device uses sound waves that produce echoes when beamed inside the body. These waves will then produce an image that medical practitioners use to diagnose the patient's illness or condition.

Majority of ultrasound procedures are performed using ultrasound equipment outside of the body. However, some medical conditions require that the sonar device be inserted into the body.

How the procedure works

Ultrasound devices are commonly used by physicians or specialists to obtain an image of a patient's internal organs. The image is produced when a probe is moved over an area of the body, such as the stomach. The probe emits sound waves that penetrate the skin and sends an echo back to the probe. The echo is recorded and transmitted as images to a monitor. However, the quality of the images can be affected by several factors.

  • Air and gas
  • Layers of fat
  • Bone
  • Skills of the operator

When an ultrasound is used

Ultrasound is commonly used as a diagnostic tool. However, it can also be used in screening procedures or a treatment programs. The most common uses of ultrasound are to:

  • Evaluate the performance of the heart (echocardiography). The procedure can be performed either as a trans-thoracic (probe used outside the body) or trans-esophageal (probe is inserted into the esophagus through the mouth)
  • Evaluate blood clots in vessels – ultrasound can detect blood clots in conditions such as superficial or deep venous thrombosis, aneurysms, or stenosis. It is often used on stroke patients.
  • Evaluate Abdominal Structures – ultrasound is used to detect gallstones, determine if there is an infection in an organ, find blockages in the bile ducts, check for appendicitis or kidney stones, and to find the causes of conditions like lower abdominal pains.
  • Evaluate the thyroid gland to find tumors or nodule growth.
  • Evaluate knee joints to check for fluid buildup
  • Help physicians insert an intravenous line when it is difficult to detect a vein
  • Evaluate the womb during pregnancy
  • Find genital and/or prostate abnormalities
  • Diagnose cancer

Associated risks

Ultrasound is a safe procedure, and there have been no reported risks associated with the procedure. However, because of its limitations, some doctors may order additional imaging tests such as an x-ray, MRI, or CT-scan, which have associated risks because of the use of radiation.

How an Ultrasound is performed

The doctor will first inform you what you'll need to do in order to prepare for an ultrasound. In some cases, the doctor may ask the patient to go on a fast for at least 8 hours, especially when the area to be examined is around the abdomen. Food inside the intestines can affect the quality of the ultrasound images.

You will then be asked to lie down on a table with the portion of your body to be tested exposed. The sonographer (ultrasound technician) or the doctor will then apply a special gel to the area. The gel helps the probe move easily over the skin and prevent any friction. The gel also helps in transmitting the sound waves into the body.

As the sonographer or doctor moves the probe around the area, low-frequency sound waves are transmitted into the body. However, you won't be able to hear the sound because they are at a frequency that is too high for the human ear. The sound waves will bounce back when they hit dense objects. The computer records the echo and displays the image on a computer monitor.

The doctor may adjust the pressure on the probe from time to time or ask you to change your position to achieve a better angle.

Once the doctor is satisfied with the images, the gel is wiped off, and you can return to your daily activities or your hospital room. The technician or doctor will need some time to analyze the image, especially when checking for abnormalities. In pregnancy cases, the doctor will normally be able to perform the analysis during the procedure.

To analyze the image, the doctor or the technician will need to be well versed in the structure of a normal organ. The doctor will be able to tell if there are any abnormalities in your organs by examining the images closely. In some cases, the doctor may require further tests, such as a tissue test to provide an accurate diagnosis of the abnormality.


  • American Institute of Ultrasound in Medicine.
  • Focused Ultrasound Foundation.
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