# Feasibility of Near-Infrared Spectroscopy for Monitoring Tissue Oxygenation During Uterus Transplantation and Hysterectomy

## TL;DR

This study explores using near-infrared spectroscopy to monitor tissue oxygen levels during uterus transplants and hysterectomies, showing promising results for tracking blood flow changes.

## Contribution

The study introduces near-infrared spectroscopy as a potential real-time, non-invasive tool for monitoring uterine graft perfusion.

## Key findings

- StO2 levels decreased during hysterectomy as blood vessels were ligated, showing a clear correlation with reduced perfusion.
- StO2 levels increased progressively during UTx as blood vessels were reconnected, indicating improved tissue oxygenation.
- The results suggest that NIRS could be a viable method for monitoring graft viability during these procedures.

## Abstract

Background/Objective: Thrombosis is the leading cause of graft failure and immediate hysterectomy following uterus transplantation (UTx). Currently, there is no standardized method for real-time assessment of UTx graft perfusion. This feasibility study aims to evaluate the utility of a near-infrared spectroscopy (NIRS) probe for non-invasive monitoring of local cervical tissue oxygenation (StO2) during UTx. As proof-of-concept for the NIRS device, cervical StO2 was also measured during non-donor hysterectomy and bilateral salpingo-oophorectomy to establish its capacity to reflect perfusion changes corresponding to vascular ligation. Methods: The ViOptix T. Ox Tissue Oximeter NIRS probe was attached to four uterine cervices during hysterectomy procedures and three separate donor cervices during UTx. Real-time StO2 measurements were recorded at critical surgical steps: baseline, ovarian vessel ligation, contralateral ovarian vessel ligation, uterine vessel ligation, contralateral uterine vessel ligation, and colpotomy for hysterectomy; donor internal iliac vein anastomosis to recipient external iliac vein, donor internal iliac artery anastomosis to recipient external iliac artery, contralateral donor internal iliac vein anastomosis to recipient external iliac vein, contralateral donor internal iliac artery anastomosis to recipient external iliac artery, and donor and recipient vagina anastomosis for UTx. Results: During hysterectomy, average StO2 levels sequentially decreased: 70.2% (baseline), 56.7% (ovarian vessel ligation), 62.1% (contralateral ovarian vessel ligation), 50.5% (uterine vessel ligation), 35.8% (contralateral uterine vessel ligation), and 8.5% (colpotomy). Conversely, during UTx, StO2 progressive increased with each anastomosis: 8.9% (internal iliac vein- external iliac vein), 27.9% (internal iliac artery-external iliac artery), 56.9% (contralateral internal iliac vein-contralateral external iliac vein), 65.9% (contralateral internal iliac artery-contralateral external iliac artery), and 65.2% (vaginal anastomosis). Conclusions: The inverse correlation between StO2 and vascular ligation during hysterectomy and the progressive rise in StO2 during UTx suggests that cervical tissue oximetry may serve as a non-invasive modality for monitoring uterine graft perfusion. Further studies are warranted to determine whether these devices complement current assessments of uterine graft viability and salvage thrombosed grafts.