If the gallbladder is functioning, the outline of the gallstone is revealed in the x-rays by the contrast material. By using ultrasound and cholecystography together, a doctor can identify gallstones in the gallbladder 98 percent of the time. However, the tests may give false-positive results in a few people who don't have gallstones. When a person has abdominal pain, jaundice, chills, and a fever, gallstones in the bile duct are a strong possibility. Blood test results usually show a pattern of abnormal liver function that suggests bile duct obstruction.
Several tests can provide the additional information needed to make a firm diagnosis.
Ultrasound scanning and CT can show whether the bile duct is dilated, but the ducts can be obstructed without being dilated. The x-ray techniques help detect an obstruction and, if present, whether it is caused by a gallstone. Which diagnostic x-ray technique is used depends on the situation. If the diagnosis is fairly certain, many doctors perform one of the x-ray techniques before deciding on surgery. If the diagnosis is uncertain, ultrasound scanning may be performed first.