Illuminating Calot’s Triangle: Can ICG Obviate the Need for Laparoscopic Subtotal Cholecystectomy?

Laparoscopic cholecystectomy (LC) has been the gold standard for symptomatic gallstone disease since the 1990s. Its widespread adoption has reduced morbidity, length of stay, and cost compared with open cholecystectomy. Yet, one of its enduring challenges remains bile duct injury (BDI), a complication associated with significant long-term morbidity, litigation, and even mortality. The critical view of safety (CVS), first described by Strasberg in 1995, was designed to minimize this risk by mandating clear identification of the cystic duct and artery before division. Yet, in cases of severe inflammation, extensive fibrosis, or distorted anatomy, CVS may be difficult, unsafe, or impossible. In such situations, surgeons often resort to subtotal cholecystectomy—a safer alternative that overrules patient safety over complete anatomical removal, as there is a known risk of bile duct damage, even if performed by an experienced surgeon. Subtotal cholecystectomy has long been recommended as a safe rescue technique in these situations, leading to the prevention of significant ductal damage ahead of anatomical completion.[1] The advent of fluorescence cholangiography using indocyanine green (ICG) and near-infrared (NIR) imaging has opened new avenues of interest in enhancing intraoperative biliary tract visualization. This real-time, radiation-free, non-invasive technique can trace biliary anatomy even before the dissection of Calot’s triangle. This raises an important question: Can ICG reduce, or even obviate, the need for subtotal cholecystectomy? ICG is a fluorescent, water-soluble dye that has a strong affinity for plasma proteins and is exclusively excreted in bile. When exposed to NIR light, it emits fluorescence that can be captured by specially equipped laparoscopic systems, enabling the visualization of the cystic duct, common bile duct, and occasionally, the segmental hepatic ducts. Most protocols recommend injection 60–120 min preoperatively. Typical doses range from 2.5 to 5 mg intravenously and are well tolerated; the only true contraindication is a prior severe hypersensitivity reaction to ICG. Historically, iodine allergy (such as shellfish or povidone–iodine allergy) was listed as a contraindication, but current evidence shows no cross-reactivity and such patients can safely receive ICG. Severe hepatic dysfunction is not an absolute contraindication; however, impaired excretion in advanced liver disease or cholestasis may reduce fluorescence quality and limit its utility.[1,2] Compared to intraoperative cholangiography (IOC), which requires cystic duct cannulation and exposes both patient and team to radiation, ICG cholangiography is technically simple, reproducible, and provides continuous real-time imaging throughout dissection. These advantages explain the surge of clinical interest and publications evaluating its role in both elective and emergency cholecystectomy.[2] Multiple studies have evaluated ICG in standard and difficult LC. A systematic review by Vlek et al.,[1] on 27 studies with 1337 patients demonstrated that ICG improved cystic duct and common bile duct (CBD) visualization compared with white light, particularly in obese and those with complex anatomy. In another meta-analysis, ICG significantly increased the ease of identifying cystic duct–common bile duct junction, common hepatic duct (CHD), even in situations where inflamed gallbladders were variable.[2] Dip et al.[3] in a meta-analysis compared ICG fluorescence versus white light. Out of 4990 abstracts screened, five studies employing NIR fluorescent cholangiography were included (three laparoscopic and two robotic cholecystectomy; n = 1603). For comparison, 11 studies without fluorescence guidance were analyzed (five laparoscopic, four robotic, and two mixed approaches; n = 5070). The pooled analysis demonstrated that ICG fluorescence significantly enhanced biliary tract visualization, facilitated shorter operative times, and was associated with lower rates of BDI compared with standard white-light cholecystectomy. While large-scale comparative trials are still required, early evidence indicates that intraoperative use of ICG-based NIR fluorescent cholangiography significantly lowers the risk of BDI and the likelihood of conversion to open surgery when compared with standard white-light cholecystectomy.[3] A prospective cohort reported zero conversions in the ICG group compared to 2.4% in the control during difficult cholecystectomies. The use of real-time ICG fluorescence cholangiography during LC enhances visualization and delineation of the biliary anatomy and thus may contribute to improving the safety of the procedure.[4] For decades, IOC has been used to define anatomy and detect CBD stones. However, its adoption has been limited due to technical complexity, time, cost, and radiation exposure. Meta-analysis by Lim et al.[5] demonstrated that ICG was at least equivalent to IOC in biliary visualization, with faster execution and no radiation. Seven studies (481 patients) were included.[2] Among seven studies comprising 275 patients, five demonstrated improved visualization of the cystic duct (RR = 0.90, P = 0.12, 95% CI 0.79–1.03, I² = 74%) and common bile duct (RR = 0.82, P = 0.09, 95% CI 0.65–1.03, I² = 87%) when using ICG fluorescence cholangiography. In four studies with 223 patients, ICG fluorescence cholangiography showed higher rates of cystic duct–common bile duct junction identification compared with IOC (RR = 0.68, P = 0.06, 95% CI 0.45–1.02, I² = 94%). Similarly, four studies involving 210 patients reported superior visualization of the CHD with ICG fluorescence cholangiography relative to IOC (RR = 0.58, P = 0.03). Meta-analysis concluded that ICG fluorescence cholangiography is safe, and it improves visualization of CHD.[5] Boni et al.[6] reported superior visualization of the CHD with ICG compared to IOC, highlighting its role in difficult anatomy.[6] ICG thus appears to provide a safe, efficient, and radiation-free alternative to IOC. Does ICG reduce the frequency of subtotal cholecystectomy procedures and have an impact on the rate of subtotoal cholecystectomy? The available evidence is still evolving but provides encouraging insights. Ambe et al.[4] suggest ICG-guided LC had lower conversion rates to open surgery and reduced need for subtotal dissection or removal of the gall bladder. Dip et al.[3] suggested that in cases where CVS was not achievable, ICG fluorescence often permitted safe completion of total LC, reducing the “bail-out” threshold. Lim et al.[2] noted that although ICG improved visualization, it could not completely overcome severe fibrosis or dense adhesions, where subtotal remained necessary. Thus, while ICG reduces the frequency of bail-out procedures, it does not abolish their necessity. Despite its promise, ICG is not without limitations. Severe inflammation is an important hurdle. In cases of gangrenous cholecystitis or frozen Calot’s, fluorescence may be obscured by dense adhesions. Interpretation of fluorescence requires training, as misinterpretation during learning curve can be dangerous. Standardization remains a challenge, as optimal dosing and timing protocols vary considerably across studies. Another limitation is resource constraints. Availability of NIR-capable laparoscopic and robotic platforms is limited in many centers, particularly in low- and middle-income countries.[7] Looking ahead, several promising directions are emerging. The integration of ICG with robotic platforms has already enhanced its utility, as systems like the da Vinci Firefly™ offer seamless toggling between white light and fluorescence. Promising avenues are with the association of artificial intelligence (AI). AI-driven image recognition may further enhance biliary mapping, creating “augmented reality” in the surgical field. Coupling fluorescence with stereoscopic vision may allow unprecedented anatomical clarity, as in 3D laparoscopy. Beyond biliary surgery, ICG is being applied in colorectal, urological, and thoracic procedures for perfusion assessment and oncological mapping.[3-5] ICG fluorescence cholangiography represents a powerful adjunct in LC. It improves visualization, reduces conversion rates, and lowers the threshold for safe completion of total LC, thereby potentially decreasing reliance on subtotal cholecystectomy. In the face of severe inflammation, dense adhesions, or distorted anatomy, subtotal cholecystectomy remains the safest bail-out. The future likely lies in a complementary approach, where ICG empowers surgeons to maximize safety while minimizing the need for subtotal resections.[3,4,7] In conclusion, ICG fluorescence cholangiography represents a powerful adjunct in LC. By improving real-time visualization of biliary anatomy, it reduces conversion rates and enhances the likelihood of achieving total cholecystectomy. These benefits collectively suggest a potential reduction in the reliance on subtotal cholecystectomy as a bail-out strategy. However, it does not render subtotal procedures obsolete, as certain complex situations will always require their use. ICG should therefore be regarded as an evolving ally—augmenting, but not replacing, sound surgical judgment. As technology advances and evidence accumulates, ICG fluorescence may well reshape the paradigm of biliary surgery, but at present it serves best as a complement to, rather than a substitute for, the selective use of subtotal cholecystectomy. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

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