The misdiagnosis of common bile duct stones with ultrasound.

Ultrasound is now widely used to demonstrate the presence of gall-stones in the gall bladder and common bile duct in jaundiced patients. The ultrasound appearance of gall-stones is characteristic and consists of strong, bright reflections with shadowing distally, though stones smaller than 3 or 4 mm may not always show shadowing. We report our experience with large common bile duct stones which do not show the characteristic features of gall-stones and so may be misdiagnosed as tumour masses. The possible reasons for these appearances are discussed.