What is the role of intraoperative fluorescence imaging (ICG)?

Learn in 30 seconds

The main points of this article:

• ICG + NIR = a special dye and camera that make tissue “glow.”
• Three commonly discussed uses: anastomotic perfusion, lymph/tumor mapping, critical anatomy (e.g. bile ducts).
• Well-perfused tissue may glow bright green; ischemic areas can stay darker.
• Allergy is rare but possible; it is not mandatory in every operation.
• Technology supports decisions; it does not guarantee zero leak or injury risk.

How does it work?

When given intravenously, ICG is cleared by the liver and, depending on dose and timing, can also enter the bile ducts. On an NIR camera the tissue shows fluorescent glow. The surgeon gets extra visual clues for “is this end well perfused?”, “is that structure a bile duct?”, or “where is the lymphatic path?”

What is it used for in surgery? (three main uses)

Three frequently discussed areas:

• Anastomotic tissue perfusion (tissue viability): Blood supply at planned bowel join margins is assessed. Well-perfused tissue glows bright green; poorly perfused zones may remain dark. The surgeon aims to place the suture/staple line on better-vascularized tissue — this can help reduce leak risk; it does not zero it.
• Lymph node and tumor mapping (oncologic surgery): In selected cases, lymphatic channels and sentinel lymph nodes can be marked with fluorescence to support resection and staging plans.
• Visualization of critical anatomy: Extrahepatic bile ducts (fluorescent cholangiography) or, in selected scenarios, structures such as ureters can be made clearer under NIR than under standard white light — helping reduce injury risk.

“No ICG means incomplete surgery” or “ICG means no leak” are false. Indication follows center protocol and the case.

Which operations discuss it?

Common examples:

• Colorectal anastomosis — assessing join-line perfusion
• Gallbladder surgery — making bile-duct anatomy more visible in selected cases
• Liver surgery — segment / margin visualization (center-dependent)
• Lymph mapping — selected oncologic scenarios

A simple analogy

Think of fog lights on a night road: they do not rebuild the road; they improve visibility. Fluorescence does not “rewrite” anatomy; it makes perfused or dye-bearing structures clearer. Even with fog lights, careful driving is needed — misinterpretation and technical error remain possible.

Limits and safety

Rare allergic reactions to ICG have been reported; tell the team about iodine sensitivity. Image quality depends on dose, timing, fat tissue, and equipment. False-negative/positive readings can occur — that is why classic surgical principles are not replaced.

Relation to robotic surgery

Platforms such as da Vinci have integrated fluorescence modes used in colorectal and other fields. Robot does not mean automatic ICG; indication and interpretation are the surgeon’s. See the robotic surgery hub pages.

Known points / overstatements

Known: it can be a useful helper for visualizing perfusion and some anatomic structures. Overstatement: “ICG zeros leak risk,” “it dyes every cancer cell,” “surgery is unsafe without this technology.”