What is done during a HIDA scan?

B.Z.

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, also referred to as cholescintigraphy, 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.

HIDA imaging is done by a nuclear scanner, which takes pictures of the patient's biliary tract over the course of about 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.

Usually, HIDA scans are ordered for patients who are suspected of having an obstruction in the biliary tract, most commonly those who are thought to have a stone blocking the cystic duct leading out of the gallbladder. Such a scenario is consistent with acute cholecystitis, which often requires surgical removal of the gallbladder. In cholecystitis, HIDA will appear in the bile ducts, but it will not enter the cystic duct or the gallbladder -- a finding that indicates obstruction. 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.