A dose of 2.5 mg of ICG is administered intravenously during patient preparation by anesthesia, about 30–45 min before surgery. If fluorescence is not detected in the liver after 60 min, an additional dose of 2.5 mg ICG is again injected intravenously. SSRC starts in the usual fashion [15]. Once the exposure of Calot’s triangle is achieved, the camera view is switched to fluorescence mode for an initial identification of the biliary anatomy (Fig. 6.2). Then, the dissection of Calot’s triangle begins with the incision of the peritoneum and continues as usual, alternatively switching from white to NIR light allowing views of the fluorescent bile ducts in real time. In this way, the surgeon can follow a road map for a safe skeletonization of the cystic duct and the cystic artery, especially in presence of accessory structures (Fig. 6.3). The cystic duct may be clipped under fluorescence before sectioning, especially if it is very short and if there are problems in the biliary confluence. If there are problems with the vascular anatomy during the cystic artery skeletonization, it is possible to proceed with a further injection of 2.5 mg of ICG and, after 10–20 s, obtain a view of the hepatic and cystic arteries and their divisions, and avoid any damage to anomalous branches, especially the branch to the sixth hepatic segment.

During the detachment of the gallbladder from the liver bed, the use of fluorescence to define the boundary between the gallbladder and liver bed is useful, especially in cases of a thin or an intrahepatic gallbladder, and to visualize any aberrant Luschka ducts (Fig. 6.4). After the procedure, a final fluorescence view of the operative field may be prudent.

From July 2011 to December 2013, 104 patients underwent SSRC with ICG NIR-cholangiography for symptomatic cholelithiasis and gallbladder polyposis. Five out of 104 patients suffered from acute cholecystitis (4.8 %). Mean BMI was 24.7 kg/m².

Mean operative time and mean console time were 71 min and 24.1 min, respectively. No statistically significant differences in operative times between standard SSRC (our previous experience) and NIR-fluorescence imaging system SSRC were observed. There were no conversions, BDIs, intra- or postoperative complications or adverse events; mean hospital stay was 1.6 days.

The rates of visualization of the cystic duct, the common hepatic duct, and the common bile duct were 94 %, 71 %, 74 % prior to Calot’s dissection, respectively, and 99 %, 93 %, 98 % after Calot’s dissection, respectively. At least one biliary structure was visualized in 100 out of 104 patients (96 %) before Calot’s dissection, and in 100 % of cases after Calot’s dissection.

The advantages of this method compared to the traditional radiological intraoperative cholangiography are many:

The main limitations of ICG-NIR fluorescent cholangiography are obesity and inflammations since fluorescence has the weakness of limited tissue penetration under NIR light [14]. Furthermore, the capability of this method to recognize biliary gallstones or other obstructions is low and of course IOC remains the best method to assess choledocolithiasis.

We can conclude that fluorescent cholangiography is a simple, fast, safe, and effective procedure. It allows clear real-time identification of extra-hepatic biliary anatomy in almost all patients, thus implementing the well-known advantages of SSRC over the traditional single-incision laparoscopic approach. It requires neither interaction of multidisciplinary teams nor additional time, it does not expose patients and staff to radiation and is not burdened by adverse reactions.

Surgery is progressively carried out with the da Vinci^® Si™ HD surgical system following the usual technique of vascular control and preparation of intestinal segments. Then, the optimal point of transection is evaluated and marked by the surgeon with (visible) light. A dose of 5.0–10 mg of ICG is now administered intravenously and after approximately 30–45 s, the surgeon switches to fluorescent vision (Fig. 6.5).

If the site chosen for the section does not appear to be sufficiently perfused, the section line may be revised and the stapler can be moved to a more proximal/distal location according to the best fluorescence reflected point. In case of doubt, the test can be repeated after waiting for a few minutes to allow the dye to washout. However, depending on the tissue, the green fluorescent intensity appears different and at different times.

Regarding the colonic stumps, the vessels of the epiploic appendices and mesentery turn green first, then the green spreads across the intestinal wall. The antimesenteric border of the descending and transverse colon is always a little paler, because the vascularization of the tenia is less intense due to the thickness of muscle tissue. The perfused segments gradually become green until they assume a bright green color, in contrast with the gray segments that are not well vascularized. Further checks may be carried out before and after performing the anastomosis.

With regard to the rectal stump, the pelvic wall turns green first (as does the uterus in women), because it is highly vascularized. After few seconds, the rectal stump colors up allowing the assessment of perfusion at the selected point (Fig. 6.6). The ends of the section lines of the rectum in Knight-Griffen anastomosis or of the colon in latero-lateral anastomosis are often referred to as critical points of leakage for their potential minor irroration: particular attention should be paid to their perfusion.

The potential advantages of bowel perfusion assessment using fluorescence system integrated into the da Vinci^® system appear interesting but so far only limited clinical data can be found in literature.

Jafari et al. [22] have recently analyzed the effectiveness of NIR-ICG in reducing the rate of anastomotic leak after robotic-assisted low anterior resection (LAR) for rectal cancer in a retrospective case–control study. They compared LAR with and without fluorescence imaging and reported a change in the proximal transection point in 3 out of 16 patients (19 %) and a reduced leak rate of 6 % when compared to 18 % for the control group. Moreover, they described that the overall risk of leak decreased of 12 % in the ICG fluorescence group.

Promising outcomes have been also reported by Bae et al. [17] in two case reports. The authors applied the ICG fluorescence during robotic LAR for cancer to better demark the ischemic area in the distal rectum so that the surgeon was helped to define the distal resection margin. Patients had an uneventful postoperative course.

Hellan et al. [23] have recently published the outcomes of a prospective multicenter study evaluating the impact of fluorescence imaging on visualization of perfusion and subsequent change of transection point during left-sided robotic colorectal surgery. Fluorescence imaging was applied on 40 patients resulted in a change of the proximal transection location in 40 % (16/40) of the candidates: two patients (5 %) with a change in transection line developed an anastomotic leak at postoperative days 15 and 40. Authors conclude that fluorescence imaging provides additional information during determination of transection line in left-sided colorectal procedures and this results in a significant change of transection location, particularly at the proximal transection site.

From September 2011 to December 2013, we have performed 100 full-robotic multiport colorectal resections for benign and malignant diseases (unpublished data) using fluorescence for bowel stump evaluation: 40 right colectomies, 30 low and ultralow anterior rectal resections, 25 left colectomies, and 5 splenic flexure resections. We routinely chose the transection line, after mesenteric section and bowel preparation, according to intestinal perfusion as shown by fluorescence imaging system. There were no intra-operative or anesthetic complications associated with the injection of ICG dye and fluorescence bowel assessment was easily accomplished in real-time in 100 % of the cases with no additional operative time.