Laparoscopic cholecystectomy is one of the most commonly performed procedures in adult surgery. A rare but serious complication of laparoscopic cholecystectomy is bile duct injury, with a reported incidence of 0.3-1.5 %. Bile duct injury is often caused by misinterpretation of the anatomical structures rather than by insufficient technical skills. Generally, bile duct injury leads to bile leakage, causing abdominal sepsis. It can also lead to obstruction, with obstructive jaundice, eventually potentially leading to a need for liver transplantation in the worst case. Late recognition is common in bile duct injuries, resulting in significant morbidity and mortality, a lower quality of life and extra costs. A recent expert consensus report identified establishment of the critical view of safety as the single most important factor for overall safety during laparoscopic cholecystectomy. However, evidence suggests that surgeons may actually achieve this view far less often than they believe.

Numerous intraoperative visualization techniques and technologies have been developed to enhance the safety of laparoscopic cholecystectomy. There are mainly two intraoperative imaging techniques to consider: first, the historical X-ray-based intraoperative cholangiography, and secondly the emerging fluorescence-based intraoperative near-infrared cholangiography. Large retrospective and prospective studies have looked at the benefit of routine intraoperative radiographic cholangiography for detection of common bile duct stones and to identify or prevent bile duct injury. Whether this procedure should be performed routinely is still an active subject of debate as systematic reviews are inconclusive; however, several of the larger retrospective studies observed a decrease in frequency and severity of bile duct injury when intraoperative cholangiography is performed. Limiting factors for performing radiographic laparoscopic cholangiography include: it requires specific expertise in the technique and its interpretation; it involves the use of ionizing radiation; it is time-consuming; and it creates a risk for bile leakage and duct injury itself, since puncturing and cannulation of the cystic duct is required. These limitations justify the quest for alternative, less complicated techniques to visualize biliary anatomy during cholecystectomy. Fluorescence-based intraoperative near-infrared cholangiography during laparoscopic cholecystectomy has been introduced by Ishizawa et al. in recent years as a non-invasive, radiation-free, low-cost alternative for realtime visualization of the biliary anatomy. This technique requires near-infrared laparoscopic imaging systems, as well as the intravenous injection of a fluorophore, i.e., indocyanine green, which is eliminated through the biliary tree. Following exposure to the near-infrared fluorescenc light source, indocyanine green becomes fluorescent and highlights relevant biliary structures. Since the pioneer studies, a large number of trials have been conducted and several protocols are currently underway, in order to establish the clinical efficacy of near-infrared cholangiography. A recent systematic review of clinical studies on near-infrared cholangiography has reported high visualization rates of biliary structures, as a surrogate marker of clinical efficacy, before dissection of Calot's triangle. However, one of the most significant drawbacks of near-infrared cholangiography following systemic indocyanine green injection lies in the very high background signal due to the rapid accumulation of indocyanine green in the liver, which can impair the visualization of the biliary structures. The keys to avoiding this inconvenience are the dose of indocyanin green and the time of administration before the surgical procedure. So far, studies used a dose of indocyanin green above 2,5mg. To avoid this effect at these doses, the authors administer the contrast many minutes or even hours before starting the surgical procedure.