# Visibility in Endourologic Workup (VIEW): Comparison of Gas and Saline Cystoscopy

## TL;DR

This study compares gas and saline cystoscopy in a model of blood in urine, finding gas cystoscopy improves visibility and usability.

## Contribution

A novel ex vivo comparison of gas-based versus saline cystoscopy for improved visibility during macrohematuria.

## Key findings

- Gas cystoscopy showed significantly better visibility ratings compared to saline cystoscopy.
- Gas cystoscopy was rated as easier to use by participants.
- All participants successfully identified targets in both conditions.

## Abstract

Introduction

Macrohaematuria often compromises cystoscopic visibility. We therefore compared gas-based versus saline cystoscopy in a standardized ex vivo macrohematuria model to assess visibility, procedure completion, and observed procedural performance.

Methods

In a monocentric, two-arm, open-label, randomized crossover pilot, physicians performed cystoscopy on ex vivo porcine bladders modified to mimic human access. Macrohematuria was simulated using a blood-analogue solution. Each bladder was distended with ambient air (180 ml; manual syringes; no intravesical pressure control) or saline (180 ml) in randomized sequence. Three predefined intravesical markings served as visibility targets. The primary endpoint was time to identify all the markings; secondary endpoints included subjective visibility (five-point Likert), perceived visual impairment, ease of use, and iatrogenic trauma (modified Objective Structured Assessment of Technical Skills (OSATS)). Paired and nonparametric tests were prespecified for ordinal outcomes.

Results

Thirteen physicians (urologists and surgical residents) completed both modalities. All participants identified all targets in both conditions. Visibility ratings favored GASCYS (good/excellent 92.3% vs 38.5%; p=0.0019). Ease-of-use ratings uniformly favored GASCYS (p= 0.0012). Perceived visual impairment was lower with GASCYS (trend; p=0.067).

Conclusion

Ambient-air cystoscopy was feasible in a standardized ex vivo macrohematuria model and was associated with improved perceived visibility and usability, highlighting its potential for further investigation in clinical studies. Clinical evaluation needs to define effectiveness, safety parameters (including gas type and pressure control), and indications for gas distension in diagnostic cystoscopy during hematuria.