Air vs. Liquid: A Study on Cystoscopy Performance and Visibility Enhancement in Macrohematuria Cases

Official title

AIROSCOPY - A Prospective, Randomized, Controlled, Single-Centre Superiority Study Comparing Air-Based Versus Saline-Based Flexible Cystoscopy for the Identification of the Bleeding Source in Patients With Macroscopic Haematuria

Overview

Macroscopic haematuria is a common urological emergency. Diagnostic cystoscopy is the gold standard for identifying the bleeding source; however, blood and clots within the bladder significantly impair endoscopic visibility when saline is used as the distension medium. Air-based cystoscopy, a technique first described in the 19th century, exploits the immiscibility of gas and blood to maintain clear visualisation even during active bleeding. Despite its theoretical advantages, no randomised clinical data exist to support its use. AIROSCOPY is a prospective, randomised, controlled, single-centre superiority study comparing air-based versus saline-based flexible cystoscopy in patients with macroscopic haematuria (Grade III-V). Patients are randomised 1:1. Only the index cystoscopy (first randomised modality) contributes to all study endpoints. A second cystoscopy with the alternative modality is performed solely for patient safety to ensure no diagnostic disadvantage from study participation. This second examination is not analysed. The primary endpoint is identification of the bleeding source during the index cystoscopy (binary: yes/no). Secondary endpoints include time to source identification, total procedure duration, urologist-rated visibility (Likert scale), and patient comfort (Likert scale).

Detailed description

Background: Continuous bladder irrigation (CBI) is the current standard management for haematuria, but can delay diagnostic cystoscopy. Gas-based cystoscopy may allow earlier and clearer visualisation of the bladder mucosa.

Design: Prospective, randomised (1:1), controlled, parallel-group, open-label, single-centre superiority trial. Randomisation is stratified by haematuria grade and history of transurethral resection (TUR-B/P), using REDCap.

Intervention: Index cystoscopy with either air (up to 240 ml by syringe) or saline (up to 240 ml by syringe), according to randomisation. A second cystoscopy with the alternative medium follows immediately, exclusively to ensure no diagnostic disadvantage for the patient (results not analysed).

Sample size: N=40 (20 per arm), based on detection rates of 86% (air) vs. 38% (saline), two-sided α=0.05, 80% power, with 20% attrition allowance.

Statistics: Chi-square test (Fisher's exact test) for the primary endpoint; risk ratio and risk difference with 95% CI reported.

Interventions

• Procedure Air-based flexible cystoscopy
  Flexible cystoscopy with manual air insufflation (up to 240 ml) via bladder syringe for bladder distension and visualisation.
• Procedure Saline-based flexible cystoscopy
  Flexible cystoscopy with manual saline irrigation (up to 240 ml, 0.9% NaCl) via bladder syringe for bladder distension and visualisation.

Primary outcome measures

• Identification of the underlying cause of macroscopic haematuria during the index cystoscopy [Time frame: Immediately after completion of the index cystoscopy (intraoperative)]

Secondary outcome measures (4)

• Time to source identification [Time frame: Intraoperative]
• Total procedure duration [Time frame: Intraoperative]
• Urologist-rated visibility [Time frame: Immediately after index cystoscopy]
• Patient comfort [Time frame: Immediately after index cystoscopy]

Eligibility criteria

Inclusion criteria

• Persistent macroscopic haematuria Grade III-V within 48 hours after hospitalisation
• Age ≥ 18 years
• Unexplained macroscopic haematuria requiring diagnostic cystoscopy
• Ability to give written informed consent

Exclusion criteria

• Pregnant or lactating women
• Haemodynamic instability or urgent need for operative or interventional cystoscopy (requiring cystoscopy within < 24 hours of screening)
• Ureteral stent in situ
• Active urinary tract infection
• Transurethral resection of the bladder (TURB) or prostate (TURP) within the last 6 weeks

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Diagnostic

Study locations

Switzerland · 1 center

• Kantonsspital Baden AG, Department of Urology — Baden

Identifiers

NCT: NCT07618221 · 2026-00787 · 2026-00787

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗