An ultrasound scan is a diagnostic imaging procedure used to assess soft tissue structures such as muscles, blood vessels, and organs.

Ultrasound uses a transducer that sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed at certain locations and angles, the ultrasonic sound waves move through the skin and other body tissues to the organs and structures within. The sound waves bounce off the organs like an echo and return to the transducer. The transducer picks up the reflected waves, which are then converted by a computer into an electronic picture of the organs or tissues under study.

Different types of body tissues affect the speed at which sound waves travel. Sound travels the fastest through bone tissue, and moves most slowly through air. The speed at which the sound waves are returned to the transducer, as well as how much of the sound wave returns, is translated by the transducer as different types of tissue.

Ultrasound is used to view internal organs as they function (in ‘real time’), and to assess blood flow through various vessels. Ultrasound procedures are often used to examine many parts of the body such as the abdomen, breasts, female pelvis, prostate, scrotum, thyroid and parathyroid glands, and the vascular system. During pregnancy, ultrasounds are performed to evaluate the development of the fetus.

Technological advancements in the field of ultrasound now include images that can be made in a three-dimensional view and/or four-dimensional view. The added dimension of the 4D is motion, so that it is a 3D view with movement. 4D ultrasound is predominantly used in obstetric scanning and can be used to enhance visualization of fetal abnormalities, picked up by conventional imaging, such as cleft lip, so that parents can recognize what the doctors are describing.

Different ultrasound techniques exist for different conditions. Examples of some of the more common types of ultrasound examinations include the following:

• Doppler ultrasound: Used to see structures inside the body, while evaluating blood flow at the same time. Doppler ultrasound can determine if there are any problems within the veins and arteries.
• Vascular ultrasound: Used to see the vascular system and its function, including detection of blood clots.
• Abdominal ultrasound: Used to detect any abnormalities of the abdominal organs (i.e., kidneys, liver, pancreas, gallbladder), such as gallstones or tumours.
• Renal ultrasound: Used to examine the kidneys and urinary tract.
• Obstetric ultrasound: Used to monitor the development of the fetus.
• Pelvic ultrasound: Used to scan the uterus, ovaries and/or bladder.
• Breast ultrasound: Used to examine a mass in the breast tissue, and for surveillance in conjunction with mammography.
• Thyroid ultrasound: Used to see the thyroid gland and to detect any abnormalities.
• Scrotal ultrasound: Used to further investigate pain in the testicles.
• Musculoskeletal ultrasound: Used to examine any joint or muscle pain for conditions, such as a tear.
• Interventional ultrasound: Used as a guide in minimally invasive procedures such as biopsies.

There is different preparation for each ultrasound depending on the type of scan you are having:

Pelvis, Kidneys, Lower Abdomen, Bladder:

• It is important to have a full bladder for this scan.
• 1 hour before your appointment, empty your bladder then drink 1 litre of water.
• Do not empty your bladder again until after your scan.

Gall Bladder, Upper Abdomen:

Morning Appointments:

• Eat a light meal the night before your appointment but do not eat any fatty food (i.e. butter, milk, eggs, cheese, fried food).
• Have nothing to eat or drink in the morning before your scan.

Afternoon Appointments:

• Eat a light meal the night before your appointment as above.
• On the day of the scan eat a light breakfast with no fat.
• Have nothing further to eat or drink until after your scan.

Abdomen & Pelvis:

• Follow the preparation for a gall bladder & upper abdominal scan and also have a full bladder.

Obstetric Scans:

• Patients up to 8 weeks gestation: It is important to have a full bladder for this scan. Follow the preparation for a pelvic ultrasound.
• Patients over 8 weeks gestation: There is no preparation required.

A clear gel is placed between the transducer and the skin to allow for smooth movement of the transducer over the skin and to eliminate air between the skin and the transducer for the best sound conduction. The transducer is moved across the skin and is placed at different angles to obtain images of the area of interest. These images are saved onto a DVD.

There are no confirmed adverse biological effects on patients or sonographers caused by exposure to ultrasound.