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

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

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).

Study Overview

• Status: Not yet recruiting
• Conditions: Hematuria; Bladder Disease; Hematuria - Cause Not Known; Macrohematuria
• Intervention / Treatment: Procedure: Air-based flexible cystoscopy; Procedure: Saline-based flexible cystoscopy

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.

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Lasse Petersen, Dr. med. univ.; Phone Number: +41 56 486 3083; Email: lasse.petersen@ksb.ch

Study Locations

• Switzerland
  • Canton of Aargau
    • Baden, Canton of Aargau, Switzerland, 5404
      • Kantonsspital Baden AG, Department of Urology
      • Contact: Lasse Petersen, Dr.med. univ.; Phone Number: 0041 56 486 3083; Email: lasse.petersen@ksb.ch

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Air Cystoscopy; Flexible cystoscopy using air as the distension medium (up to 240 ml, manually administered via bladder syringe). This is the index cystoscopy for patients randomised to air.	Procedure: Air-based flexible cystoscopy; Flexible cystoscopy with manual air insufflation (up to 240 ml) via bladder syringe for bladder distension and visualisation.
Active Comparator: Saline Cystoscopy; Flexible cystoscopy using 0.9% saline as the distension medium (up to 240 ml, manually administered via bladder syringe). Standard-of-care procedure. This is the index cystoscopy for patients randomised to saline.	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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Identification of the underlying cause of macroscopic haematuria during the index cystoscopy	Binary outcome (yes/no). Assessed in real time by the operating urologist during the index procedure and documented immediately after completion. 'Yes' if a specific bleeding source (e.g., tumour, prostate bleeding, stone, vascular lesion) is identified; 'No' otherwise.	Immediately after completion of the index cystoscopy (intraoperative)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to source identification	Minutes from insertion of the cystoscope to first identification of the bleeding source during the index cystoscopy.	Intraoperative
Total procedure duration	Minutes from insertion to removal of the cystoscope during the index cystoscopy.	Intraoperative
Urologist-rated visibility	5-point Likert scale (1 = very poor to 5 = excellent), completed by the operating urologist immediately after the index cystoscopy.	Immediately after index cystoscopy
Patient comfort	Description: 5-point Likert scale (1 = very uncomfortable to 5 = very comfortable), completed by the patient immediately after the index cystoscopy.	Immediately after index cystoscopy

Collaborators and Investigators

• Sponsor: Kantonsspital Baden

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): February 1, 2028
• Study Completion (Estimated): June 1, 2028

Study Registration Dates

• First Submitted: May 25, 2026
• First Submitted That Met QC Criteria: May 25, 2026
• First Posted (Actual): June 1, 2026

Study Record Updates

• Last Update Posted (Actual): June 1, 2026
• Last Update Submitted That Met QC Criteria: May 25, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Urogenital Diseases; Pathologic Processes; Male Urogenital Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urination Disorders; Hemorrhage; Pathological Conditions, Signs and Symptoms; Urinary Bladder Diseases; Hematuria
• Other Study ID Numbers: 2026-00787 (Other Identifier: EKNZ (Ethikkommission Nordwest- und Zentralschweiz))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No