What is cholescintigraphy (HIDA scan)?
Cholescintigraphy is a test done by nuclear medicine physicians to
diagnose obstruction of the bile ducts (for example, by a gallstone
or a tumor), disease of the gallbladder, and bile leaks. It sometimes
is referred to as a HIDA scan or a gallbladder scan.
How is cholescintigraphy (HIDA scan) done?
For cholescintigraphy, a radioactive chemical is injected
intravenously into the patient. The test chemical is removed from
the blood by the liver and secreted into the bile which is produced
by the liver. The test chemical then disperses everywhere that the
bile goes-into the bile ducts, the gallbladder, and the intestine. A
camera that senses radioactivity (like a Geiger counter) is then
placed over the patient's abdomen and a "picture" of the liver, bile
ducts, and gallbladder is obtained which corresponds to where the
radioactive chemical has traveled within the bile-filled liver, bile
ducts, and gallbladder. Cholescintigraphy takes approximately two
How are the results of cholescintigraphy (HIDA scan) used?
There are various patterns of radioactivity that can be seen
following the injection of the radioactive chemical, and each has a
different meaning. If the test chemical is not detected in the
liver, a diseased liver is probably indicated. If the chemical is
absorbed by the liver but not secreted into the bile ducts, there
probably is a complete obstruction of the bile ducts exiting the
liver. When the test chemical fails to appear in the gallbladder,
but is detected in the intestine, there probably is an obstruction of
the cystic duct leading to and from the gallbladder. (Obstruction is
most commonly caused by gallstones and, less commonly, by tumors.
Parasites, and blood clots also may obstruct infrequently.) Finally,
if the chemical appears outside the liver, bile ducts, gallbladder,
or intestine, there probably is a bile leak from the bile ducts or
Cholescintigraphy is most commonly used to diagnose problems with the
gallbladder when other more commonly-performed tests, particularly
ultrasonography, are normal. Cholescintigraphy can be modified with
the addition of an intravenous injection of cholecystokinin, the
hormone that is normally released by the body after a meal. This
hormone causes the gallbladder to contract and squeeze out its bile
into the intestine. Reduced contraction of the gallbladder following
cholecystokinin (i.e., reduced emptying of the radioactivity from the
gallbladder) may mean that there is disease of the gallbladder
itself, particularly inflammation or scarring of the wall.