Overlay Visualization of the Ureter Using a Fully Intraluminal Indocyanine Green-Emitting Stent During Laparoscopic Surgery for Diverticular Disease: A Technical NoteAbstract
Introduction Ureteral injury during laparoscopic surgery for diverticular disease remains an uncommon but clinically significant issue. Chronic inflammation and fibrosis frequently obscure retroperitoneal anatomy.
Objective To describe a workflow-integrated technique using a fully intraluminal indocyanine green (ICG)-emitting ureteral stent that enables on-demand overlay visualization using a single near-infrared (NIR) platform.
Materials and Methods A fully intraluminal ICG-emitting ureteral stent was placed cystoscopically before surgery. During laparoscopy, NIR overlay mode was activated selectively at predefined high-risk steps: before peritoneal incision, during medial-to-lateral dissection around the inferior mesenteric vessels, and after colonic mobilization. Fluorescent signals were superimposed on white-light imaging to confirm ureteral position without interrupting dissection.
Results Overlay visualization allowed rapid and repeatable confirmation of ureter location. Real-time shared situational awareness was improved for the entire operative team. No intraoperative ureteral injury occurred. Adverse events were limited to those attributable to cystoscopic stent placement.
Conclusion On-demand overlay visualization using a fully intraluminal ICG-emitting ureteral stent represents a practical adjunct in laparoscopic surgery for complex diverticular disease. This technique supports organ-preserving surgery by enabling continuous dissection with real-time ureter awareness using a single imaging system.
Keywords
indocyanine green; ureteral stent; near-infrared fluorescence imaging; ureter identification; diverticular disease
Introduction
Laparoscopic surgery for diverticular disease is frequently complicated by inflammation-induced fibrosis and distortion of retroperitoneal anatomy. Although ureteral injury is uncommon, its consequences may be substantial, particularly when diagnosis is delayed.
Fluorescence-guided ureter identification using indocyanine green (ICG) has been described in colorectal and pelvic surgery.1-4 Near-infrared (NIR) light-emitting ureteral catheters have also been reported.5 However, previously described techniques either lack integration with standard white-light anatomy or require additional light sources and workflow modifications.
The novelty of the present report does not lie in the introduction of a new fluorescent device per se, but in the implementation of a workflow-integrated overlay strategy that enables selective, on-demand ureter visualization using a single imaging platform. This concept emphasizes operative efficiency and team-wide situational awareness rather than continuous fluorescence display.
Indications and Patient Selection
This technique is selectively applied in diverticular disease when ureter identification is anticipated to be challenging based on preoperative imaging or clinical findings, including severe inflammatory thickening adjacent to the ureter, diverticular stenosis, fistula formation, or prior pelvic surgery. Routine use is not recommended.
The disease context is central to treatment rationale. In colorectal malignancy, combined organ resection may be oncologically appropriate. In contrast, diverticular disease is benign, and preservation of adjacent structures is a priority. Avoidable ureteral injuries, in this setting, represent preventable morbidities. Therefore, strategies that enhance intraoperative ureter awareness without compromising efficiency are particularly relevant.
Surgical Technique
After induction of general anesthesia, a urologist places a fully intraluminal ICG-emitting ureteral stent cystoscopically.
A laparoscopic system equipped with NIR overlay capability is used. Importantly, no additional external light source is required. Overlay mode is activated selectively at predefined high-risk operative steps: First, before peritoneal incision, overlay imaging confirms the ureteral course beneath intact peritoneum, assisting in defining the medial dissection plane. Then, during medial-to-lateral dissection and central vascular handling, it is intermittently activated around the inferior mesenteric vessels before sharp dissection or energy application. Finally, after major mobilization, the imaging reconfirms ureter position relative to the retroperitoneum following colonic mobilization.
This activate-when-needed approach avoids continuous fluorescence display and repeated switching between imaging modalities. The fluorescent signal is superimposed on white-light anatomy, enabling simultaneous visualization of tissue planes and ureter location (Fig. 1). As a result, operative rhythm is maintained and confirmation can be performed within seconds at critical decision points.
Overlay visualization of the left ureter using a fully intraluminal ICG-emitting ureteral stent during laparoscopic surgery for diverticular disease. (A) Before peritoneal incision: NIR overlay demonstrates the ureter beneath intact peritoneum. (B) During medial-to-lateral dissection: overlay visualization adjacent to the inferior mesenteric vessels. (C) After colonic mobilization: ureter visualized in the retroperitoneum confirming separation from mobilized mesentery.
Discussion
The principal contribution of the current report is conceptual rather than device-driven. Previous studies have demonstrated the feasibility of ICG-based ureter visualization.1-6 A systematic review has summarized the growing body of evidence.7 However, these reports primarily focus on visualization feasibility. The present technique differs by emphasizing:
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Workflow integration, as fluorescence is incorporated into predefined surgical steps rather than used continuously.
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Overlay strategy, in which ureter visualization is superimposed onto white-light anatomy, minimizing cognitive load.
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Single-platform efficiency, as no additional light source or equipment is required.
These elements collectively aim to enhance intraoperative safety without prolonging operative time or interrupting dissection. In benign diverticular disease, in which organ preservation is fundamental, this balance between safety and efficiency is particularly relevant.
Importantly, this report does not attempt to demonstrate superiority or quantify reduction in ureteral injury rates. As a technical note, its purpose is to describe a reproducible strategy that may be selectively adopted in high-risk situations. Future prospective evaluation may clarify its impact on operative metrics and complication rates.
The limitations of the present study include the requirement for cystoscopic placement, cost considerations, and potential catheter-related hematuria, or urinary tract infection. Selective use in anatomically challenging diverticular cases appears appropriate.
Conclusion
On-demand overlay visualization using a fully intraluminal ICG-emitting ureteral stent represents a workflow-oriented strategy to enhance ureter safety in laparoscopic diverticular surgery. By combining selective activation with single-platform overlay imaging, this approach supports efficient, organ-preserving dissection in benign colorectal disease without disrupting the operative flow. Because activation is integrated into standard laparoscopic imaging without modification of surgical steps, the learning curve is expected to be minimal.
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Funding
The authors declare that they did not receive funding from agencies in the public, private, or non-profit sectors to conduct the present study.
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Ethical Approval
The study was approved by the Institutional Review Board (Approval No. UOEHCRB20-204), and written informed consent was obtained from the patient.
Data Availability
Data will be available upon request to the corresponding author.
Acknowledgments
The authors would like to thank the Urology team for perioperative ureteral stent placement.
References
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Editor-in-Chief:
Henrique Sarubbi Fillmann.
