Abdominal ultrasound (US) scanning, abdominal US imaging, abdominal ultrasonography or sonography.
Ultrasound scans are high frequency sound waves too high for humans to hear. After the Titanic hit an iceberg and sank in 1912, many people researched ways to find underwater icebergs. During this time, SONAR (sound navigation and ranging), which uses ultrasound, was developed.
Ultrasound waves sent to the part of the body being examined are reflected, refracted, or absorbed at the interfaces inside the body. Echoes that return in this way carry information about the size, distance, and uniformity of internal organs. This is displayed on a monitor to create an ultrasound image.
During abdominal sonography, a hand-held device called a "transducer" is placed on the area being examined and moved around. This transducer generates ultrasound and sends it through the body. It also detects the returning echoes and transmits them as electrical signals. Because one transducer continuously generates many ultrasound waves while detecting echoes, a real time image can be produced on a viewing monitor. These images can be recorded on videotape, or images can be frozen and recorded on to film.
During abdominal sonography, lubricating gel is applied to the skin so that the transducer can be moved around to produce real time images. Ultrasound is similar to audible sound in that it can pass through water and human organs easily, but it can't pass through air or bone. So gel is applied between the transducer and the skin to bridge the gap, and effectively send the ultrasound waves.
Abdominal sonography is a useful way of examining internal organs, such as the liver, gallbladder, pancreas, kidneys, spleen, and urinary bladder.
Because US images are real time images, blood flow, blood vessels, bowel movement, and the movement of internal organs from breathing can be seen.
Safe, painless, easy, fast, and widely available
Real time imaging -- ultrasonography can be used to guide invasive procedures such as biopsy, and to visualize bowel movement and blood flow.
In case of an emergency, bedside sonography can be done without particular patient preparations.
To detect causes of fever
Serial follow up of known abnormalities in the abdomen, such as gallstones, liver cirrhosis, cyst, benign tumor, etc.
To examine blood flow; to discover blockage and/or atherosclerotic plaque, blood clot in the arteries, and veins of the abdomen
To guide invasive procedures such as needle biopsy and withdrawal of fluid
Gallstones and cholecystitis
Cancers of the liver, kidneys, pancreas, gallbladder, biliary tree
Enlarged liver, spleen, kidneys, lymph nodes
Injury -- hematoma, tear, rupture
Hemorrhage of the adrenal gland
Abdominal aortic aneurysm
You will be asked to remove your clothing and put on a hospital gown.
You will be positioned on an examination table and made to lie down on your back and lay your hands above your head. It may become necessary to change positions during the exam, and lie down on your side or sit up.
A lubricating gel is applied to the patient's abdominal area.
An apparatus known as a transducer is placed on the abdominal area and moved around to get real time images. Sometimes you will have to breathe in and hold your breath according to the technologist, sonologist, or physician's instructions.
After the examination, the gel is cleaned off and you can change back into your clothes.
Examinations usually take 10-30 minutes.
You should wear comfortable, loose-fitting clothing.
Take off your top right before the examination, and put on a hospital gown.
You should not eat or drink for as many as 12 hours before your exam.
In case of an emergency, exams can be done without special preparations.
Tell the sonographer, sonologist, or physician sonologist conducting the examination about pain, bleeding, or any other symptoms you might have. Also, telling the examiner about past ultrasounds and surgeries is helpful, and sometimes provides crucial information.
The image recorded on film or videotape is interpreted and analyzed by a radiologist (a physician specialist experienced in ultrasound and other radiology exams). The official report is sent to the practitioner who requested the examination.
The personal doctor's office informs the patient when the results are in and the outcome, and uses them as a reference in evaluating and treating the patient.
There is no known risk to humans from diagnostic ultrasound.
Unlike X-ray examinations, ultrasound does not use radiation. Pregnant women and fetuses can be safely examined.
Ultrasound does not penetrate air or bone. So if an abnormality is behind bowel gas, ribs, or calcified rib cartilage, it may not be discovered.
Because ultrasound is absorbed and reflected inside the body, only some of the waves reach deep places farthest from the transducer. There's a limitation to ultrasound's ability to look deep into the body. Of two tumors of equal size, the tumor closest to the transducer will be discovered more readily than the more distant one. Examinations, consequently, are not as productive for obese, tall patients as they are for thin or petite ones.
Ultrasonography is an operator-dependent, subjective test. The more experience the operator has, the better the patient listens to his instructions (hold your breath, do not eat, repress the urge to urinate), the better the results. Further, the more the operator knows about the patient's past medical history, current medical history, and the results of other radiological and laboratory tests, the better the examination. For best results, before taking ultrasonography, ask if the practice where the scan is being performed is accredited either by the American Institute of Ultrasound in Medicine or the American College of Radiology.
Abdominal ultrasonography can't discover all abnormalities. If there's an ulcer, small polyps, or diverticuli, or infection/inflammation in the stomach, intestine, or colon, ultrasound will not be effective in finding them. In such cases, endoscopy, barium enema, or an upper GI series must be done. Further, in the case of abdominal injury, ultrasound is an incomplete examination, and a CAT scan will have to be done.