Digital subtraction cholangiography: a new technique for visualising the common bile duct during cholecystectomy.

Operative cholangiography is for most surgeons a routine part of every cholecystectomy. Computerised digital subtraction angiography was adapted for operative cholangiography using a portable machine. After cannulation of the cystic duct the background image was subtracted before injecting contrast. Only the contrast within the bile duct appears on the monitor and resolution is high. A permanent record was made on 10 X 10 cm spot films. Eighteen pre-exploratory cholangiograms were performed using this method. In 12 no stones were demonstrated on digital subtraction cholangiography (DSC), nor were there clinical indications of common bile duct stones. These patients underwent cholecystectomy only. Stones were demonstrated on DSC in 3 patients and all had stones at exploration of the common bile duct (CBD). Three patients had no stones demonstrated on DSC but were explored on clinical grounds. No stones were found. Postoperative T-tube cholangiograms confirmed the absence of stones in 5 patients. A retained stone was present in one patient who had not had a postexploratory examination at operation and was not related to the use of this cholangiographic technique. DSC combines the benefits of image intensification and still radiography and has been accurate in both predicting and excluding common bile duct stones.