Hello, the HIDA scan is used to detect gallbladder problems. As you could guess the liver takes over the elimination of the injected substance, so that the kidneys are not under a heavy load. I couldn t tell whether you need this test though. If you re having constant pain then the ultrasound scan should suffice. There are other signs besides the stones like gallbladder wall thickening and fluid collections or dilation of the duct in case of an obstruction. Other tests are suggestive like the complete blood count (increased white blood cells), liver function tests and bilirubin (increased enzymes and bilirubin). If you d like a more thorough advice, please provide more details and I ll be glad to help. The test itself is not a danger though. Kind Regards!