# Intraoperative Evaluation of Bladder Perfusion Using Indocyanine Green Fluorescence Imaging During Total Pelvic Exenteration After Interruption of Blood Flow From the Internal Iliac Vessels

## TL;DR

This study shows that bladder blood flow remains intact after cutting off internal iliac vessels, thanks to blood from the pubic side, supporting safer cancer surgeries.

## Contribution

Demonstrates bladder perfusion is preserved via pubic-side blood flow after internal iliac vessel resection using ICG fluorescence imaging.

## Key findings

- Bladder perfusion was successfully visualized in all patients after internal iliac vessel division.
- Perfusion originated exclusively from the pubic side, confirming alternative blood supply routes.
- Older age was significantly associated with delayed visualization of bladder perfusion.

## Abstract

In lateral lymph node dissection (LLND) for locally advanced or recurrent rectal cancer, concomitant resection of the internal iliac vessels is sometimes required. Because the bladder receives its primary blood supply from branches of the internal iliac artery, concerns arise regarding bladder perfusion when these vessels are resected. However, the extent to which bladder perfusion depends on the internal iliac system remains unclear.

Between 2020 and 2023, 25 patients with locally advanced or recurrent rectal cancer who underwent total pelvic exenteration (TPE) with bilateral LLND were prospectively enrolled. After division of all ventral branches of the internal iliac vessels, including the umbilical, obturator, and vesical vessels, bladder perfusion was evaluated intraoperatively using indocyanine green (ICG) fluorescence imaging. Time to visualization of bladder perfusion was recorded.

Bladder perfusion was successfully visualized in all patients without complications. Median time to visualization was 30 s (interquartile range, 20–50). Perfusion originated exclusively from the pubic side, and fluorescence of the entire bladder wall was confirmed after mobilization. Patients were classified into early (≤ 30 s) and delayed (> 30 s) visualization groups. Older age was significantly associated with delayed visualization (p = 0.044), whereas no other clinical or surgical factors showed associations.

Bladder perfusion was maintained even after complete interruption of both arterial supply and venous drainage from the internal iliac vessels, owing to blood supply from the pubic side. These findings support the safety of internal iliac vessel resection during extended LLND in rectal cancer surgery.

Intraoperative ICG fluorescence imaging demonstrated that bladder perfusion was maintained through blood flow from the pubic side, even after complete division of the internal iliac vessels during total pelvic exenteration.