Real-time Visualisation of the Extrahepatic Biliary System Using Indocyanine Green Fluorescence Cholangiography During Laparoscopic Cholecystectomy: A Prospective Cross-sectional Singlecentre Study of 199 Cases

Introduction: Bile Duct Injury (BDI) is an infrequent but serious complication of Laparoscopic Cholecystectomy (LC) and is frequently related to misidentification of biliary anatomy. Conventional Intraoperative Cholangiography (IOC) is invasive, requires fluoroscopy and may be technically difficult in inflamed or distorted anatomy. Fluorescent Cholangiography (FC) using Indocyanine Green (ICG) and Near Infrared (NIR) imaging permits real-time visualisation of the extrahepatic biliary tree without radiation. Aim: To determine the visualisation rate of the Cystic Duct (CD), Common Hepatic Duct (CHD), Common Bile Duct (CBD) and CDCHD confluence under ICG-NIR fluorescent cholangiography at the stage of the Critical View of Safety (CVS) during LC. Materials and Methods: A single-centre prospective crosssectional observational study was conducted at the Department of Surgery and Surgical Gastroenterology, Meenakshi Mission Hospital and Research Centre (MMHRC), Madurai, Tamil Nadu, India from October 2016 to September 2018. A total of 199 consecutive patients (≥15 years) undergoing elective or emergency LC received intravenous ICG (0.05 mg/kg, max 5 mg of 2.5 mg/mL solution) 90 minutes before skin incision. NIR imaging (Stryker 1588 AIM and Karl Storz SPIES/ IMAGE1 S systems) was used intraoperatively. Visualisation was independently rated by two senior surgeons (Cohen’s kappa=0.82). Cases were classified as simple or complex on operative pathology. Data were analysed using IBM Statistical Package for Social Sciences (SPSS) version 26.0; Chi-square/ Fisher’s-exact tests with 95% Wilson confidence intervals were applied (p<0.05 significant). Results: Of 199 patients, 94/199 (47.2%) were male and 105/199 (52.8%) female; mean age 49.4±15.7 years; mean BMI 25.7±5.1 kg/m². Simple cases: 107/199 (53.8%); complex cases: 92/199 (46.2%). Overall visualisation rates at CVS were CD 168/199 (84.4%; 95% CI 78.7-88.9), CHD 165/199 (82.9%; 77.1-87.6), CBD 182/199 (91.4%; 86.7-94.7) and CD-CHD confluence 172/199 (86.4%; 80.9-90.6). In simple vs complex cases, respectively: CD 99.0% vs 67.3% (p<0.001); CBD 100% vs 81.5% (p<0.001). Anatomical variations included short CD (22/199, 11.1%), long CD (20/199, 10.1%), independent right posterior sectoral duct (17/199, 8.5%), trifurcation at CHD (5/199, 2.5%) and Phrygian cap (3/199, 1.5%). There were no conversions, no BDI and no ICG-related allergic reactions. One postoperative death occurred from sudden cardiac arrest (unrelated to ICG). Conclusion: ICG-NIR fluorescent cholangiography is a safe and useful adjunct for real-time visualisation of extrahepatic biliary anatomy during LC. Visualisation is reduced in complex inflammatory cases, but the technique still facilitates identification of key ducts and anatomical variations and may enhance surgical safety when combined with the CVS principle.