Near-Infrared Fluorescence Imaging for Intraoperative Ureter Identification: A Systematic Review

Abstract

Introduction: Identification of ureters in abdominopelvic surgery is challenging due to their close anatomical relation with other vital structures. Failed identification can lead to iatrogenic ureter injury. Literature reports various numbers of incidence rates (0.5%-10%), with highest rates (54%) in laparoscopic hysterectomies. Over the years, ureter identification using near-infrared (NIR) fluorescence imaging showed promising results and has become a field of interest for research and development of different identification methods. This systematic review provides an overview of all NIR contrast agents available for clinical research and care, in all types of surgery.

Methods: A literature search was performed systematically in the PubMed and Embase database. Clinical study reports, case series, and case reports were selected based on predefined inclusion and exclusion criteria. Preferred Reporting Items for Systematic reviews and Meta-Analysis guidelines were used to extract and portray all relevant data. Each article was scored for identification rate, defined as percentage of required ureters identified.

Results: Forty-five articles were included, with the majority investigating indocyanine green for ureter identification. Identification rates of 95% and higher were obtained in most articles reporting fluorescent techniques using 800 nm fluorescent contrast agents. No significant treatment-related adverse events or complications have been reported in literature for intravenous dyes. The use of stents for indocyanine green or fluorescent catheter application is associated with a higher incidence of technique-related adverse events.

Conclusions: NIR fluorescent imaging appears effective and safe for intraoperative ureter identification. The choice of dye should be determined by their characteristics, clinical availability, and by the surgical challenge of each individual case.

Keywords: Fluorescence; Iatrogenic ureter injury (IUI); Indocyanine green (ICG); Methylene blue (MB); Near-infrared (NIR); Ureter.