Objective and background
The purpose of this new technique is to improve visualization of the extrahepatic bile ducts at laparoscopic cholecystectomy. The idea depends on the fact that intravenously-administered fluorescein is excreted by the liver and its concentration in bile reaches 500 times that of plasma. Ultraviolet A (UVA) excites fluorescein and causes it to emit green light.
Method:
Animal study. Twelve New Zealand rabbits had laparotomy under general anesthesia and were intravenously injected with fluorescein at a dose of 7.5mg/kg. The room light was reduced and ultraviolet light at 365nm wavelength was cast on the gall bladder and bile ducts area. The clarity of biliary topography under this light was visually observed.
Human study. Seven patients who had symptomatic gallstones underwent laparoscopic cholecystectomies that were guided by this technique. After induction of pneumoperitoneum intravenous 500mg fluorescein was administered. Ultraviolet A (wavelength 365nm) from a LED light source was used to induce fluorescence of bile. It was delivered by a rod-like device that was designed and built by the authors. The device was introduced through the epigastric trocar. Ultraviolet visualization was used at three occasions during each procedure; before dissection of Callot’s triangle, before clipping of the cystic duct and at the end of the procedure in order to look for possible bile leaks. At each occasion the conventional white light transmitted through the telescope was reduced to 20-30% of its intensity.
Results:
Animal study. In all rabbits the extrahepatic biliary topography was clearly delineated by the shining green light of the excited fluorescein in bile. Vessels were clearly distinguished from bile ducts.
Human study. Within four to five minutes the bile ducts were shining with green fluorescence, which distinguished them from the surrounding tissues. In all cases identification of the extrahepatic biliary anatomy by the fluorescence technique preceded its identification with the conventional white light. Fluorescence remained for the whole duration of operation that extended for 40-82 minutes.
The total ultraviolet energy exposure was calculated to range from 0.6-1.8J/cm2. This is far less than the maximum safe permissible daily exposure of 15J/cm2 that was set by The American Conference of Governmental Industrial Hygienists.
Conclusions: At laparoscopic cholecystectomy intravenous fluorescein injection and ultraviolet A excitation induce bile ducts fluorescence. The technique allows better and earlier real time visualization of biliary anatomy than with the conventional white light. The technique is safe, simple and inexpensive. It serves as an additional tool that would improve safety of laparoscopic cholecystectomy.