Minimally invasive procedure is currently the gold standard for cholecystectomy. However, for common bile duct stones, it is still a matter for debate. An increasing number of studies describe the benefits of one-stage treatment for gallstones combined with CBD stones using minimally invasive surgery instead of ERCP combined with LC [19, 20]. For patients with a history of previous gastrectomy with gastrojejunostomy, ERCP and LCBDE were both possible solutions for CBD stones [21]. However, the difficulty of ERCP increases with preceding Billroth II reconstruction and multiple/large CBD stones removal [22]. There are two key challenges related to CBD stone surgery, namely anatomical localization, and laparoscopic skills. In recent years, many articles described the technique and the results of LCBDE, but relatively fewer researches focused on how to improve anatomical localization, especially in cases of inflammation or with previous abdominal surgeries. Generally, LCBDE would only be considered if the CBD stone is relatively simple, and the patients have not previously undergone complex abdominal surgeries (i.e., stomach, ascending colon, or liver surgeries). Because the extensive adhesion due to previous complex abdominal surgeries may hinder the identification of biliary structures. With the assistance of near-infrared fluorescent laparoscopy, the identification of the biliary tract becomes more feasible in the patients with dense adhesion, so the success rate of LCBDE could increase.

The near-infrared fluorescence was widely used in the different field. In the previous study, this was used for lymph node dissection during laparoscopic gastrectomy [23], pancreatic and periampullary cancer [24] or gallstone [25, 26]. But there were only few articles about the application of NIR in LCC. With our experience in applying near-infrared fluorescence on laparoscopic cholecystectomy, we wanted to extend the application of near-infrared fluorescence [12]. As described in our previous article, two methods can be used for the illumination of the CBD, namely intrabiliary ICG administration or systemic ICG administration. The details of their benefits have been described in our previous article [11, 12]. In patients with obstructive jaundice, internal drainage such as ERBD or external drainage such as PTGBD or PTCD may be performed preoperatively. In our study, we injected ICG into external drain tubes in patients with PTGBD or PTCD, and injected ICG to the systemic circulation in patients without biliary drainage.

In our result, the rate of previous surgical history in the LCC group was only 11.8% and was significantly higher, 47.6%, in the NIR-CC group. However, the conversion and complication rates were comparable between LCC and NIR-CC groups. With higher incidence of preceding abdominal operations in NIR-CC group, the surgical complexity should raise substantially due to possible extensive adhesion. Nonetheless, with the help of NIR, the rate of converting to laparotomy was not higher than the LCC group. This result indicates that near-infrared fluorescence is very helpful in aiding the visualization of the biliary structure to greatly improve the success rate of finishing the surgery with minimally invasive approach.

Most conversions in the NIR-CC group were not related to anatomical localization. Only one patient was converted to open surgery due to an unvisualized CBD. Two other conversions were due to an extremely large stone impaction and iatrogenic colon injury. The most common reason for conversion in the LCC group was related to unclear anatomy or adhesions. In the NIR-CC group, the success rate of fluorescent enhancement of the CBD was 85% compared to 24% in white light imaging. Fluorescent imaging can prevent accidental CBD injuries. It can also show the border of the CBD and prevent erroneous positioning of the choledochotomy. This erroneous positioning can occur in cases of unclear CBD anatomy and can increase the difficulty of stone removal and the closure of the CBD.

In our series, some selection bias may exist. The NIR scope was introduced as the new technique after the evidence of our trial for laparoscopic cholecystectomy [12]. Difficult cases or patients having undergone previous abdominal surgery would be advised to undergo this image-guided surgery. As a result, the percentage of previous abdominal surgery was higher in the NIR-CC group. The difficulty of surgery was also increased and grade III-V adhesions [27] or Nassar grade III-IV adhesions were about 71% (15/21) in the NIR-CC group, but the conversion rate was not increased compared to the LCC group. The visualization rate of the CBD, upper margin and lower margin of CBD imaging were 85, 62, and 57% respectively. By adding fluorescent imaging, the successful rate of minimally invasive surgeries for CBD stones will increase and surgeons will feel more confident when faced with difficult cases.

The major differences between intrabiliary and systemic ICG administration were fluorescence signal onset and background noise. Intrabiliary administration can provide real-time imaging without background fluorescent noise. However, perforation of the gallbladder with intraoperative bile leakage can lead to failure of fluorescent imaging. Regarding systemic administration, the timing of the injection was crucial. It took 30 to 40 min for the ICG to get into the bile and generate fluorescent signals. It also yields less clear fluorescent imaging because of the background noise. The common problem of those two methods is that the fluorescent signal could not be retrieved if the CBD wall was thicker than 0.5 cm.