You are probably referring to a "HIDA scan", a procedure that is used on patients who seem to have trouble with their gall bladders. This is a nuclear imaging procedure that is used to create an image of the gall bladder in order to evaluate its level of functioning and its health. HIDA stands for Hepatobiliary Imino-Diacetic Acid, and the scan is called a Hepatobiliary Imino-Diacetic Acid scan, a cholescintigraph, or simply a HIDA scan. The phrase is often either misheard or mispronounced as hydroscan.
The HIDA scan essentially involves injecting a radioactive substance into your bloodstream as a tracer; this eventually reaches your biliary system, allowing the imaging equipment to capture an image of your gall bladder. The entire procedure is usually completed within two hours, but in some cases it could take longer. It begins with the injection of the radioactive tracer, which is usually a substance known as technetium-99m. This is quite painless, and many patients don’t even realize when this step is finished, or even when it started. Next, as the tracer circulates through your blood stream and reaches your liver and gall bladder, the imagine machine will track its progress. Once the tracer reaches your gall bladder, the machine will take the required images, and you can then get up and walk around. Images of a healthy gall bladder can usually be captured within an hour, but if there is severe blockage or inflammation, the tracer will take longer to pass through the bladder. The doctors may wait for up to four hours after the injection to see whether images can be recorded. Typically, this will be followed by a procedure in which gall bladder contractions are induced with the help of a drug. If your gall bladder is functioning normally, this part of the procedure will also be painless. However, the worse your gall bladder is, the more pain you will experience during this procedure. A mild dysfunction will usually cause only mild cramps, but a serious blockage could cause a considerable amount of pain. However, most patients agree that this pain is nothing compared to the pain they regularly experience. If you have been asked to take this test, it is probably because you have been complaining of the typical symptoms of gall bladder disease. There is therefore no need for you to worry – if your gall bladder is healthy, the entire HIDA test will be painless, and if there is in fact a problem, the pain will be relatively mild.
answered by G R