Introduction:
Indocyanine green (ICG) fluorescence imaging has become an invaluable tool for assessing tissue perfusion and lymphatic drainage during colorectal surgeries. It is beneficial in determining the extent of resection, especially when preoperative imaging results are ambiguous.

Aim:
This paper aims to highlight our strategy for preoperative tumour localization in managing an elderly male with a colon tumour.

Case study:
A 72-year-old male presented with an endoscopically obstructed ascending colon tumour and was scheduled for a laparoscopic extended right hemicolectomy. However, preoperative computed tomography revealed a synchronous tumour involving both the ascending and transverse colon. To pinpoint the exact tumour location, a repeat endoscopy with clip placement was performed, followed by abdominal radiography. Surprisingly, the clip was located in the transverse colon rather than the ascending colon as initially suspected. Intraoperatively, we injected ICG at the tumour site and used laparoscopic imaging to map the ICG flow. Based on these findings, we adjusted our surgical plan and performed a left hemicolectomy with primary anastomosis instead of the initially planned procedure.

Results and discussion:
We summarize the relevant studies and discuss the impact of leading technologies on preoperative colon tumour localization.

Conclusions:
Colorectal tumour localization using endoscopic clip placement and ICG fluorescence imaging are reliable for guiding surgeons to better surgical outcomes, especially when dealing with tumours in watershed areas.