Modern gastrointestinal surgery increasingly combines advanced minimally invasive techniques with technologies designed to provide surgeons with additional intraoperative information. One of the most important developments in this area is Indocyanine Green (ICG) fluorescence imaging, which allows visualization of tissue perfusion using near-infrared technology. During WALS 2025, Dr. Deep Goyal discussed the role of ICG in bowel perfusion and its potential value in improving intraoperative assessment during gastrointestinal and colorectal procedures.

Bowel perfusion is fundamental to successful gastrointestinal surgery. When a surgeon removes a diseased section of intestine and creates an anastomosis, the two bowel ends must have adequate blood supply for healing. If perfusion is compromised, the risk of impaired healing and anastomotic complications can increase. Consequently, surgeons have traditionally relied on several intraoperative indicators to determine whether bowel tissue is sufficiently viable.

Conventional assessment includes evaluation of bowel color, mesenteric pulsation, tissue appearance, bleeding from the bowel edge, and anatomical knowledge of the vascular supply. These methods remain important and form the foundation of surgical decision-making. However, they are partly subjective and may be difficult to interpret in complex cases.

ICG fluorescence provides an additional method of visualization. Following intravenous administration, ICG circulates within the bloodstream and produces fluorescence when exposed to near-infrared light. Specialized laparoscopic, open, or robotic imaging systems can detect this fluorescence and display the perfused bowel in real time.

One of the most important uses of ICG is intraoperative assessment before bowel transection. The surgeon can evaluate the proposed resection area and identify the transition between better-perfused and relatively poorly perfused tissue. If the fluorescence pattern raises concern about perfusion, the operative plan may be reconsidered, including modification of the transection point when appropriate.

This capability can be particularly valuable during colorectal cancer surgery, where extensive vascular dissection and lymphadenectomy may alter blood flow to the remaining bowel. An appropriate anastomotic site needs both adequate perfusion and acceptable mechanical conditions. ICG can contribute additional information to the decision-making process.

ICG may also be assessed after reconstruction. Once the anastomosis has been created, fluorescence imaging can provide another view of the vascularity of the bowel around the reconstructed area. This can complement other intraoperative assessments and help the surgical team evaluate the overall situation before completing the procedure.

A key reason for interest in ICG is the possibility of reducing anastomotic complications. Several studies have reported changes in operative strategy after ICG assessment. In one published series, fluorescence findings led to changes in the planned operative strategy in a proportion of patients, including changes to the resection level.

More recent evidence has strengthened the scientific discussion. A 2026 systematic review and meta-analysis of randomized controlled trials involving 4,754 patients reported a statistically significant reduction in overall colorectal anastomotic leaks with adjunctive ICG fluorescence angiography, with particularly strong findings in left-sided and rectal resections.

These findings are important, but they should be interpreted appropriately. Anastomotic leakage is multifactorial. Perfusion is only one component. Other factors include anastomotic tension, technical construction, tissue quality, infection, patient comorbidities, nutritional status, disease characteristics, and the complexity of the procedure. ICG can therefore provide useful additional information but cannot independently guarantee a successful anastomosis.

The WALS 2025 lecture by Dr. Deep Goyal also highlights the potential value of ICG in difficult and complex bowel cases. When inflammation, adhesions, previous surgery, radiation-related tissue changes, or altered anatomy make visual assessment challenging, fluorescence imaging can provide an additional perspective on vascularization.

In emergency gastrointestinal surgery, the ability to assess bowel viability can be particularly important. Strangulated bowel, volvulus, mesenteric ischemia, and other acute conditions may create uncertainty about the appropriate resection margin. International emergency-surgery guidance recognizes ICG angiography as an adjunct that can help evaluate intestinal perfusion and guide intraoperative decisions when available.

ICG can also be integrated into robotic surgery. Modern robotic systems may incorporate near-infrared fluorescence capabilities, allowing the surgeon to switch between conventional visualization and fluorescence imaging during the procedure. This creates opportunities for real-time assessment without changing the overall minimally invasive approach.

Another important area is gastric and bariatric surgery. Perfusion assessment may be relevant around gastric staple lines, gastric pouches, and anastomoses. Although the exact application varies by procedure, the underlying principle remains the same: adequate vascularization is necessary for healthy tissue healing.

The use of ICG also requires an understanding of its limitations. Fluorescence imaging is affected by tissue depth, camera technology, timing, dose, background fluorescence, and the way the image is interpreted. A brightly fluorescent area does not necessarily mean that every aspect of tissue viability is guaranteed, while reduced fluorescence should be interpreted in the context of the operative anatomy and other clinical findings.

Standardization and quantitative assessment remain important areas of development. Some imaging systems provide quantitative fluorescence measurements, while others are primarily qualitative. Researchers continue to investigate whether standardized fluorescence thresholds can reliably predict postoperative outcomes. Earlier research has specifically noted the need for further studies to establish clinically meaningful quantitative values.

The future of fluorescence-guided surgery may involve more advanced technologies. Artificial intelligence could potentially assist surgeons by analyzing fluorescence patterns and providing quantitative or comparative information. Improved cameras, software-based perfusion mapping, and integration with robotic platforms may further expand the applications of fluorescence imaging.

However, technology should complement rather than replace surgical expertise. A surgeon must still understand vascular anatomy, recognize abnormal tissue, evaluate tension and technical construction, and make decisions based on the complete clinical picture. ICG is best understood as an additional source of information that can support, rather than independently dictate, intraoperative judgment.

Dr. Deep Goyal's presentation at WALS 2025 provides an educational overview of these concepts and demonstrates why fluorescence-guided surgery has become an important topic in modern minimally invasive gastrointestinal surgery. The session focuses attention on the relationship between vascular perfusion, anastomotic healing, intraoperative imaging, and surgical decision-making.

For colorectal surgeons, gastrointestinal surgeons, bariatric surgeons, laparoscopic specialists, robotic surgeons, residents, fellows, and surgical trainees, the topic is highly relevant to the evolution of image-guided surgery. Learning how ICG works, when it may be useful, and how to interpret its limitations can help clinicians understand the growing role of fluorescence technology in the operating room.

The broader lesson is that modern surgery is increasingly moving toward real-time, image-guided decision-making. ICG fluorescence is one of the technologies contributing to this transformation by making vascular perfusion more visible during critical stages of gastrointestinal surgery.

Dr. Deep Goyal's WALS 2025 lecture therefore provides valuable educational insight into the role of ICG in bowel perfusion assessment, particularly its potential applications in colorectal surgery, complex bowel procedures, anastomotic planning, emergency surgery, laparoscopic procedures, and robotic surgery.

As fluorescence-guided surgery continues to develop, future research will be important to determine optimal protocols, quantitative thresholds, patient selection, and the procedures in which ICG provides the greatest clinical value. The integration of technology with sound surgical principles, appropriate training, and evidence-based decision-making will remain central to its responsible use.

Educational note: This content is intended for professional education and should not be interpreted as individualized medical advice. ICG fluorescence is an adjunctive imaging technique, and its findings must be interpreted together with anatomical, clinical, and operative information by appropriately trained healthcare professionals.