Ultrasound imaging, also called sonography, is a method of obtaining images from inside the human body through the use of high-frequency sound waves. The reflected sound wave echoes are recorded and displayed as a real-time visual image. No ionizing radiation (x-ray) is involved in ultrasound imaging.
The ultrasound transducer functions as both a generator of sound (like a speaker) and a detector (like a microphone). When the transducer is pressed against the skin it directs inaudible, high-frequency sound waves into the body. As the sound echoes from the body’s fluids and tissues the transducer records the strength and character of the reflected waves. With Doppler ultrasound the microphone captures and records tiny changes in the sound wave’s pitch and direction of the sound. These echoes are instantly measured and displayed by a computer, which in turn creates a real-time picture on the monitor.
Because ultrasound images are captured in real time, they can show movement of internal tissues and organs and enable physicians to see blood. Ultrasound imaging is used extensively for evaluating the abdominal and pelvic organs and and blood vessels. Obstetric ultrasound refers to the specialized use of sound waves to visualize and thus determine the condition of a pregnant woman and her embryo or fetus. Ultrasound is also being used to image and guide biopsy the. Ultrasound is also used to evaluate superficial structures such as the thyroid gland and testicles.
- Ultrasound scanning is noninvasive (no needles or injections in most cases) and is usually painless.
- Ultrasound uses no ionizing radiation and is the preferred image modality for diagnosis and monitoring of pregnant women and their unborn infants.
- Ultrasound images can visualize structure, movement and live function in the body’s organs and blood vessels.
- For standard diagnostic ultrasound there are no known harmful risks or effects on humans.
How should I prepare for the procedure?
You should wear comfortable, loose-fitting clothing for your ultrasound exam. For some scans your doctor may instruct you not to eat or drink for as many as 12 hours before your appointment. For others you may be asked to drink up to six glasses of water two hours prior to your exam and avoid urinating so that your bladder is full when the scan begins.
Please arrive 15 minutes before your exam. The preparations for an ultrasound vary depending on the body part you are having scanned.
If you are having an ultrasound of any Upper Abdominal Organ (Gall Bladder, Pancreas, Liver, Spleen, kidneys or aorta eat an early low-fat dinner on the night before your exam and have nothing to eat or drink for 8 hours prior to your exam.
If you are having an ultrasound of your Pelvis you will need to have a full bladder for this exam. Please drink 6 eight oz. glasses of liquid. Finish drinking this liquid one hour prior to your exam. Do Not Empty your bladder before the exam.
There is no preparation if you are having an ultrasound of your Breast, Extremity or other body parts (i.e., Thyroid).
How is the procedure performed?
The patient is positioned on an examination table. The technologist or doctor will spread some warm gel on your skin and then press the transducer firmly against your body, moving it until the desired images are captured. There may be varying degrees of discomfort from pressure as the technologist guides the transducer over your skin. Most ultrasound examinations are painless, fast and easy.