Oral cholecystogram

Oral cholecystography is a procedure used to image the gallbladder, now largely superseded by ultrasound and MRCP. It was first described by Graham et al. in 1925, using sodium tetraiodophenolphthalein.

Although rarely performed now, more modern techniques use other cholegraphic agents such as iopanoic acid and ipodate.  Following oral administration, the contrast agent gets absorbed by the bowel and concentrated in the gallbladder. Radiolucent gallstones may then be outlined as filling defects on fluoroscopic imaging.