A Narrative Review of the Usefulness of Indocyanine Green Fluorescence Angiography for Perfusion Assessment in Colorectal Surgery

Simple Summary Anastomotic leakage is one of the most dreaded complications of colorectal surgery and adequate perfusion at the anastomotic site is a well-recognized prerequisite to prevent it. Indocyanine green fluorescence angiography (ICG-FA) is a novel technology that allows real-time assessment of tissue perfusion and has become widely used in practice as it is feasible to use. However, there is no consistent evidence as to whether this new technology reduces anastomotic leakage after colorectal surgery and the results of large-scale randomized controlled trials currently underway are awaited. In addition, several methods have been proposed to objectively evaluate fluorescence using various quantitative parameters. In this review, we focus on the utility of ICG-FA in reducing postoperative anastomotic leakage in colorectal surgery, with the intention of providing an up-to-date information and discussing future perspectives in this field. Anastomotic leakage is one of the most dreaded complications of colorectal surgery and is strongly associated with tissue perfusion. Indocyanine green fluorescence angiography (ICG-FA) using indocyanine green and near-infrared systems is an innovative technique that allows the visualization of anastomotic perfusion. Based on this information on tissue perfusion status, surgeons will be able to clearly identify colorectal segments with good blood flow for safer colorectal anastomosis. The results of several clinical trials indicate that ICG-FA may reduce the risk of AL in colorectal resection; however, the level of evidence is not high, as several other studies have failed to demonstrate a reduction in the risk of AL. Several large-scale RCTs are currently underway, and their results will determine whether ICG-FA is, indeed, useful. The major limitation of the current ICG-FA evaluation method, however, is that it is subjective and based on visual assessment by the surgeon. To complement this, the utility of objective evaluation methods for fluorescence using quantitative parameters is being investigated. Promising results have been reported from several clinical trials, but all trials are preliminary owing to their small sample size and lack of standardized protocols for quantitative evaluation. Therefore, appropriately standardized, high-quality, large-scale studies are warranted.