BJU Int. 2013 Nov;112 Suppl 2:69-73.

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.

Peter J Gilling, Rana M. Reuther, Michael Addidle, Michelle M. Lockhart, Christopher M. Frampton and Mark R. Fraundorder

Department of Urology, Tauranga Hospital, Bay of Plenty District Health Board, Tauranga, New Zealand


Corresponding author:  Peter J Gilling

Suite 6, Promed House, 71 Tenth Avenue, Tauranga 3140, New Zealand

Email:; Tel. +64 7 5790466; Fax. +64 7 5784717; Mobile. +64 21 982737



OBJECTIVE: 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.

RESULTS: 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.

CONCLUSIONS: 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.

© 2013 The Authors. BJU International © 2013 BJU International.

KEYWORDS: Cidex-OPA; chlorine dioxide; flexible cystoscopy; high-level disinfection; randomised trial

PMID: 24127679



A flexible cystoscope is an endoscope that is used to examine the urethra and bladder. Being heat-sensitive, the instrument cannot be autoclaved (sterilised by heat). The most widely available alternative to heat sterilisation is high-level disinfection with a chemical disinfectant.

There are many types of flexible endoscope and imaging devices. All gain access to the cavities that they are designed to examine via the body’s openings: the mouth and anus for investigation of the gastrointestinal tract; the urethra for the bladder; the vagina for the uterus, and the nose for the upper airway and lungs.

The endoscopes used in gastroenterology are the best known and are also the largest in terms of physical size (as they have the largest cavities to navigate), and complexity in terms of the internal lumens they possess. Over the past twenty years the received view of the state of the art of endoscope disinfection has been determined by the challenges posed by gastroenterology. Whether the disinfection technology that has evolved to meet these challenges is also optimal, or necessary, for other types of endoscope is an important question for healthcare globally. In terms of procedure numbers, more patients are examined with heat sensitive instruments outside of the clinical area of gastroenterology than within it. Scarce healthcare finances may be being diverted to instrument disinfection practice that is not necessary when the most relevant outcomes of disinfection technologies are compared. The study evaluates this.

The state of the art for flexible endoscope disinfection that has emerged is the automated endoscope reprocessor (AER), a machine into which both chemical disinfectant and endoscope are placed. The AER controls the time the instrument is soaked in the disinfectant. The AER’s predecessor would be a tray or sink that would require the user to monitor the soaking time manually.

A flexible cystoscopy is a relatively quick procedure that does not require anaesthesia and can be performed outside of the hospital setting; in the case of flexible cystoscopy in the urologist’s office. A global healthcare trend is to re-locate relatively simple and safe procedures outside of the acute hospital setting in order to reduce the call upon hospitals’ resources. Flexible cystoscopy for surveillance and diagnostic purposes associated with prostate and bladder cancer is an ideal candidate and in many countries is widely undertaken in the clinician’s office. Due to the speed of the procedure it is common for multiple patients to be seen in a morning or afternoon session. Often, due to their cost, the urologist has only one or two flexible cystoscopes. The rate limiting step, therefore, for the number of patients that can be examined in a session will be the time taken to disinfect the cystoscope between cases.

The speed with which an automated machine can turn around an instrument is determined by the soak time the disinfectant takes to achieve high-level disinfection, whether the disinfectant needs to be rinsed off the instrument after the disinfection phase due to its toxicity, and the efficiencies of the machine in terms of how quickly it can move liquids through internal pipework.

The importance of this study is three-fold.

First, it compared the outcomes of two relatively new disinfection technologies that have emerged in recent years (the Stella decontamination system that incorporates certain features of an AER but retains the simplicity of a tray; and Fuse which is a chlorine dioxide high-level disinfectant) with those of the existing state of the art for endoscope disinfection (one of the world’s most widely used AER’s: the Medivator DSD-91; and the world’s most widely used high-level disinfectant: CidexOPA). The comparison included all the essential outcomes for an acceptable method of high-level disinfection:

• Microbiological efficacy achieved by both the disinfection process (Stella and AER) and high-level disinfectant (Fuse and CidexOPA) as measured by the number of positive cultures taken from washing and brushing the cystoscope, and from the Stella or AER;

• Clinical efficacy being the Impact upon the patient as measured by evidence of urogenital irritation or distress;

• Ease of use for nursing staff and surgeons.

On all measures, the new technology as represented by Stella and Fuse, was at least equivalent to the technology currently considered to be the state of the art worldwide.

Second, the comparative cost of the two technologies, both in terms of their cost of acquisition and implementation, and in terms of their operation (measured by cost per patient procedure), significantly favoured the Stella and Fuse process.

The acquisition and implementation cost of Stella and Fuse was US$4,788 and US$60,514 for CidexOPA and the AER in the conditions of the study.

Per procedure operating costs were US$11.67 for Stella and Fuse compared to US$21.82 for CidexOPa and AER. This is in part due to the substantial time saving achieved in turning around the instrument when using Fuse due to its shorter soak time and no requirement to rinse, as opposed to the necessity to rinse CidexOPA off the endoscope (a total cycle time of 7.5 minutes for Fuse in Stella vs c. 26.8 minutes for CidexOPA in AER).

Third, there have been very few randomised single-blind comparisons of endoscope disinfection technologies undertaken in the clinical setting.

The study concluded that, given the microbiological equivalence of both technologies and the user friendliness of the combination of Stella and Fuse, together with the capability of Stella and Fuse to achieve a more rapid throughput of patients, the system may become the agent of choice for high-level disinfection of flexible cystoscopies.

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