What is Abdominal Ultrasound Imaging?
Ultrasound imaging, also called ultrasound scanning or sonography, is a method of obtaining images of internal organs by sending high-frequency sound waves into the body. The reflected sound waves’ echoes are recorded and displayed as a real-time visual image. No ionizing radiation (x-ray) is involved in ultrasound imaging. An abdominal ultrasound image is a useful way of examining internal organs, including the liver, gallbladder, spleen, pancreas, kidneys, and bladder. Ultrasound images are captured in real time which can help to diagnose a variety of conditions and to assess damage caused by illness.
What are some common uses of the procedure?
Ultrasound imaging is used extensively for evaluating the kidneys, liver, gallbladder, pancreas, spleen, and blood vessels of the abdomen. Because it provides real-time images, it can also be used to:
- Guide procedures such as needle biopsies, in which needles are used to sample cells from organs for laboratory testing.
- Help a physician determine the source of many abdominal pains, such as stones in the gall bladder or kidney, or an inflamed appendix.
- Help identify the cause for enlargement of an abdominal organ.
Doppler ultrasound is a special type of ultrasound study that examines major blood vessels. These images can help the physician to see and evaluate:
- Blockages to blood flow, such as clots.
- Build-up of plaque inside the vessel.
- Congenital malformation.
With knowledge about the speed and volume of blood flow gained from an ultrasound image, the physician can often determine whether a patient is a good candidate for a procedure like angioplasty.
How should I prepare for the procedure?
Do not to eat or drink for 12 hours before your appointment.
Pelvic ultrasound – drink water.
What does the equipment look like?
The ultrasound image is immediately visible on a nearby screen that looks much like a computer or television monitor. The radiologist or sonographer watches this screen during an examination and captures representative images for storage. Often, the patient is able to see it as well.
How does the procedure work?
The ultrasound transducer functions as both a loudspeaker (to create the sounds) and a microphone (to record them). When the transducer is pressed against the skin, it directs a stream of inaudible, high-frequency sound waves into the body. As the sound waves echo from the body’s fluids and tissues, the sensitive microphone in 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. These signature waves are instantly measured and displayed by a computer, which in turn creates a real-time picture on the monitor. The live images of the examination can be recorded on videotape or on disk. In addition, still frames of the moving picture are usually “frozen” to capture a series of images.
How is the procedure performed?
When the examination is complete, the patient may be asked to dress and wait while the ultrasound images are reviewed on a monitor. Often, though, the sonographer or radiologist is able to review the ultrasound images in real time as they are acquired, and the patient can be released immediately.
What will I experience during the procedure?
Who interprets the results and how do I get them?
What are the benefits vs. risks?
- Ultrasound scanning is non-invasive (no needles or injections, in most cases) and is usually painless.
- Ultrasound is widely available and easy to use.
- Ultrasound imaging uses no ionizing radiation, and is the preferred image modality for diagnosis and monitoring of pregnant women and their unborn infants.
- Ultrasound provides real-time imaging, making it a good tool for guiding minimally invasive procedures such as needle biopsies.
- 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 effects on humans.
What are the limitations of Abdominal Ultrasound Imaging?
Ultrasound waves do not pass through air; therefore an evaluation of the stomach, small intestine and large intestine may be limited. Intestinal gas may also prevent visualization of deeper structures, such as the pancreas and aorta. Patients suffering from obesity are more difficult to image—this is because tissue attenuates (weakens) the sound waves as they pass deeper into the body.
Ultrasound has difficulty penetrating bone and therefore can only see the outer surface of bony structures and not what lies within and beyond. For visualizing bone or internal structures of certain joints, waves do not reflect clearly from bone or air. For visualization of bone, other imaging modalities, such as MRI (magnetic resonance imaging) may be selected.
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