Ultrasonography is a diagnostic imaging method that has been around for some 30 years. Sound waves are emitted from a small transducer (like a microphone) placed on the skin. The sound waves pass through the tissues and are invariably reflected and reabsorbed at interfaces between different tissues. The sound waves bounce back to the transducer in somewhat different form; the ultrasound machine computes the sound energy into a representative image. Typically, on an ultrasound image fluid appears black, and tissues such as fat appear bright or white. There have been numerous advances in ultrasound including the development of ultrasound imaging of blood vessels (color and Doppler).
Ultrasonography is a valuable first line investigation in patients with a number of abdominal complaints. It is especially useful for patients complaining of right upper quadrant pain, for the evaluation of diseases of the gall bladder or biliary tract (tubes that drain the liver or gallbladder into the small intestine) and provides valuable information about a number of internal organs within the abdomen such as the liver. Among the many conditions that may be diagnosed confidently with ultrasound are gallstones, an inflamed gall bladder, dilatation of the bile ducts, abnormal liver texture, focal liver masses or the presence of free fluid within the abdomen which itself may be associated with a variety of gastrointestinal disorders.
For the most part, no preparation is required for an ultrasound. The only exception is when it is necessary to evaluate the gall bladder in which case the patient should fast for a period of 8 hours. If the patient does not fast, the gallbladder may be contracted, and seeing it and any abnormalities such as gallstones will be more difficult. Fasting relates to both solids and liquids and is an important preparation for any ultrasound examination of the gallbladder or in a patient with right upper quadrant pain.
The ultrasound examination itself is entirely painless. The patient is asked to lie on the examination table with the appropriate body part exposed. Ultrasound gel, which is a harmless nonallergenic bactericidal gel, is applied to the end of the transducer which in turn is applied to the patients abdomen. A typical examination may take 15 to 20 minutes. The images are immediately reviewed by the radiologist; if they are satisfactory the patient may be discharged from the department.
What Happens Afterwards?
The patient can immediately resume normal activity. There are no reported adverse reactions with any form of diagnostic ultrasound. This procedure is entirely safe.