*3.3.5 Evidence of ICG usefulness in laparoscopic colorectal resection*

In regard to tumor localization, ICG-coated endoscopic clips can bring a promising new technique, as seen in a study by Lee et al. [33]. The precise localization of a tumor before surgery is vital, more so in the early stages of cancer, and the amplitude of the surgical intervention must be established. The accurate localization of a colorectal lesion ensures proper margins for resection and prevents surgical removal of healthy segments of the colon; furthermore, it can reduce the duration of surgery and prevent unnecessary colon traction and tumor handling, which could result in dissemination of tumor cells. The method abovementioned involves placing endoscopic clips coated or mounted with near-infrared fluorescent material, such as ICG, at the lesion site and determining the location of the tumor by consequently detecting the fluorescent signal through the intestinal wall (through the use of a near-infrared laparoscope).

**Figure 11.** *Robotic surgery in the operation room.*

In a research by de Nardi and team [34], a randomized trial was formulated, involving 252 cases in which laparoscopic left-sided colon and rectal resection were performed. The algorithm randomized 1:1 to intraoperative ICG or to subjective visual evaluation of the bowel blood supply without ICG. The main results were the following: ICG angiography documented insufficient blood supply of the colic stump, which implied extended bowel resection in 13 cases (11%). In the control group, 11 patients (9%) had a fistula; meanwhile, in the study group, six patients (5%) developed one anastomotic leak (p = n.s.).

Based on the general elements reviewed, it was summed up that intraoperative ICG fluorescence angiography can efficiently find correctly the vasculature of the colic stump and anastomosis in situations when colorectal resection is performed.

Despite the fact that this method guided proximal bowel resection in 13 instances, the ICG arm did not find a statistically meaningful decrease in anastomotic bowel leak rate. Transanal ICG angiography has been shown to be both feasible and effective in imaging the mucosal and anastomotic blood supply in research conducted by Sherwinter [35]. Future research in a larger community of patients is needed to fully understand the technique's potential to detect flaws in tissue perfusion that could lead to an anastomotic breakdown. Twenty patients with benign and malignant lesions underwent low anterior resection for the analysis. Indocyanine green (ICG) was injected through a peripheral iv catheter after the anastomosis was completed. Transanally, an endoscopic near-infrared imaging device (NIR) was used to test the blood supply at the level of the colon mucosa, the rectum, and the anastomotic staple axis (**Figure 12**).

#### *3.3.6 ICG monitoring for perineal wound contamination in abdominoperineal resection*

The incidence of the incisional surgical site infections in colorectal surgery was reported between 5 and 26%. Surgical site infections (SSI) in an abdominoperineal resection (APR) appear more than in other types of interventions in the case of patients with colorectal cancer. Toshiyuki et al. [36] found that perineal wounds are the most vulnerable sites, and they may be triggered by stool contamination. Indocyanine green (ICG) fluorescence testing was employed as a marker of perineal wound contamination. The study had as a method to inject indocyanine green into the rectum transanally before the operation, and fluorescence images were obtained

**Figure 12.** *Schematics of fluorescence angiography in the colorectal area.*

during the operation in patients who underwent APR. The findings, though sparse, are promising: one subject had an SSI after having no clear gross contamination, and a trace of ICG fluorescence was found in the perianal skin.

The other two cases were free of SSI, and skin treatment was carried out thoroughly before ICG contamination was removed in those cases.

Even after the normal antiseptic skin preparation, a trace of stool contamination can remain in the perineal skin area, according to the study's findings.

Furthermore, careful skin preparation is needed and it is compulsory if we are to minimize stool contamination in APR subjects (**Figure 13**).
