Subserosal Indocyanine Green Mapping in Colorectal Surgery Using an Adjustable Laparoscopic Injection Needle

Indocyanine green (ICG) fluorescence imaging is increasingly used in colorectal surgery, but reliable intraoperative subserosal injection for lymphatic mapping remains technically challenging because puncture depth control and prevention of dye spillage are essential. We developed a standardized subserosal ICG mapping technique using an adjustable laparoscopic injection needle under direct laparoscopic or robotic visualization. The serosa adjacent to the tumor is punctured with the needle tip adjusted to local bowel wall thickness, and ICG is delivered using a saline-ICG-saline sandwich technique. To minimize contamination, the outer sheath of a suction tube is positioned close to the puncture site as a protective guide for the injection needle, allowing immediate re-sheathing after injection; laparoscopic gauze is added when necessary. Fluorescence imaging is then performed to visualize lymphatic flow and fluorescent nodal basins. In our initial 10-patient experience, detection was achieved in 9 patients without puncture-related complications.