Applications of Indocyanine Green Fluorescence Imaging in Colorectal Surgery: a Narrative Review

Background and Objective: The need to optimize visualization systems in minimally invasive surgery has given rise to a growing number of applications of indocyanine green (ICG) fluorescence. This narrative review aims to summarize the existing literature about the use of this fluorophore in colon and rectal surgery. Methods: A literature search was performed using PubMed database to identify relevant articles on ICG fluorescence guided surgery and colorectal surgery. Key Content and Findings: ICG fluorescent angiography has proved to be a useful tool to assess intestinal resection line perfusion, but study heterogeneity, low statistical power and confounding evidence have prevented demonstrating a decrease in anastomotic leak in colorectal surgery. Although the application of ICG near-infrared fluorescence is a safe and reliable technique for evaluating the lymphatic flow and detecting sentinel lymph nodes in colorectal surgery, especially in early cancer stage setting, current evidence does not allow to determine its use in routine clinical practice and it is far from being sufficient to establish ultra-selective colectomies programs. Endoscopic submucosal ICG injection allows intraoperative tumor site location when performed up to a week prior to surgery, but cost-effectiveness research need to define its advantage compared to traditional permanent dyes. Intraureteral ICG instillation may reduce ureteral iatrogenic lesions, but its invasive administration prevents its use in daily routine patients. Conclusions: ICG fluorescence-based technology represents a niche of opportunities for improved visualization in the field of minimally invasive surgery. However, with the exception of angiography for the intraoperative evaluation of intestinal perfusion, the currently available evidence limits the indication for routine use of the rest of the applications. Future development of quantitative fluorescence measurement methods and established protocols may achieve better performance of this tool.