A randomised single-blind comparison of the effectiveness of Tristel Fuse (chlorine dioxide) as an office-based fluid soak, with Cidex OPA (ortho-phthaldehyde) using an automated endoscopic reprocessor (AER) as high-level disinfection for flexible cystoscopes




  • To compare the effectiveness, safety and cost of Tristel Fuse (chlorine dioxide) with Cidex OPA (ortho-phthaldehyde; 1,2–benzenedicarboxaldehyde) in an automated endoscopic reprocessor (AER) for high-level disinfection of flexible cystoscopes.

Patients and Methods

  • A randomised single-blind study comparing the high-level disinfectants Tristel Fuse as a simple office-based soak and Cidex OPA using an AER was performed. Participants were ‘blinded’ to the agent used for disinfection of the flexible cystoscopes.
  • All patients had negative mid-stream urine at baseline, (MSU) no symptoms suggestive of urinary tract infection (UTI) on the day of investigation, no recent antibiotic use or current indwelling urinary catheter.
  • Patients who underwent cystoscopic biopsy during the procedure were excluded.
  • A urine analysis was done before and 3–5 days after cystoscopy and multiple equipment cultures were performed.
  • The Urogenital Distress Inventory (UDI-6 + two questions from the ‘long-form’), symptom and quality-of-life scores were assessed before and after cystoscopy as were ease-of-use assessments and a full cost analysis.


  • In all, 180 of 465 screened participants were randomised 1:1 and the mean age was 72.1 years, 17% were females and 57% of procedures were performed for bladder tumour surveillance.
  • The urine analysis was positive in 5.4% of patients in each group and 29% (Tristel) vs 20% (Cidex) of patients had urinary leukocyturia (p = ns) after cystoscopy.
  • The turnover (minutes per cycle) was 7.5 (Tristel) vs 26.7 (Cidex). The per-procedure costs were $11.67 (American dollars) for Tristel Fuse and $21.82 for Cidex OPA with fixed costs of $4788 for Tristel Fuse and $60 514 for Cidex OPA.


  • Tristel Fuse appears to be as effective and more cost-effective than Cidex OPA for high-level disinfection of flexible cystoscopes. This has significant cost implications for the office urologist.