The intravenous cholangiogram (IVC) is a radiologic procedure for diagnosing gallstones within the larger bile ducts within the liver and the bile ducts outside the liver. Also, it can be used to detect other causes of obstruction to the flow of bile.
Today, IVC is not used much because it cannot be used in patients with many conditions and with the even minimal amount of jaundice so it is replaced by endoscopic ultrasound, endoscopic retrograde cholangiopancreatography (ERCP), and, increasingly, by MRI cholangiography.
During the procedure, an iodine-containing dye is injected intravenously into the blood and by the liver into the bile.
Iodine is dense and radioopaque (stops x-rays) and it outlines the gallstones that are radiolucent (x-rays pass through them) so they are visible on an x-ray, but sometimes the gallbladder is not seen because iodine-containing bile can bypass it and empty directly into the small intestine.
The risk of an intravenous cholangiogram is an occasional serious allergic reaction to any iodine-containing dye which can be treated, but also very rarely it can result in the death of the patient.