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A HIDA scan is an imaging test used to examine the gallbladder and the ducts leading into and out of the gallbladder.
In this test, the patient receives an intravenous injection of a radioactive material called hydroxy iminodiacetic acid (HIDA).
The HIDA material is taken up by the liver and excreted into the biliary tract. In a healthy person, HIDA will pass through the bile ducts and into the cystic duct to enter the gallbladder. It will also pass into the common bile duct and enter the small intestine, from which it eventually makes its way out of the body in the stool. If the HIDA enters the bile ducts but does not enter the small intestine, then an obstruction of the bile duct (usually due to stones or cancer) is suspected.
HIDA imaging is done by a nuclear scanner, which takes pictures of the patient's biliary tract over the course of around two hours. The images are then examined by a radiologist, who interprets the results. It is generally a very safe test and is well tolerated by most patients.
