Table of Contents
Five stages, five separate jobs
An endoscope washer disinfector is the general name for a device that cleans and disinfects the outer surface of an endoscope together with all of its channels, and does so without damaging the instrument. Detro Healthcare, which produces the Detrox range and the Detrowash devices from its facility in Esenyurt, sets the cycle out as a fixed sequence of five steps: leak testing, cleaning, disinfection, rinsing and drying. The order is not decorative. Every step is there because something specific goes wrong when it is missing, and a weak step rarely announces itself, since the scope leaves the chamber looking the same either way.
The reason these machines exist at all is a process problem rather than a chemistry problem. Detro Healthcare describes full automation as the answer to two pressures at once: endoscopy units needed a product that took human intervention out of the reprocessing loop and prevented cross contamination caused by the user, and demand from biomedical engineering pushed in the same direction. Automatic control is what absorbs the risk carried by manual cleaning and disinfection performed incorrectly, and the same devices serve the unit’s need for fast cleaning and disinfection.
Read as a chain rather than a list, the five stages divide the work like this.
| Stage | What the stage has to achieve | What is at stake when it is weak |
|---|---|---|
| Leak testing | Confirm the instrument is still sealed before any fluid reaches it | A breach lets fluid into the interior, damaging the scope and creating a space no later stage can treat |
| Cleaning | Move detergent solution across the exterior and through every channel | Soil left in a lumen sits between the disinfectant and the surface it is supposed to reach |
| Disinfection | Bring a high level disinfectant into contact with all cleaned surfaces under the cycle’s conditions | Contact that misses a lumen leaves part of the instrument untreated while the run still reports as complete |
| Rinsing | Clear disinfectant residue using water of the right microbiological quality | Unsuitable rinse water reintroduces bacteria at the last wet moment of the process |
| Drying | Leave channels dry before the endoscope is stored or used again | Residual moisture supplies the condition any surviving organism needs to multiply |
Why the leak test runs before anything gets wet
A flexible endoscope is a sealed instrument. Its working parts sit behind an outer sheath and a set of channel walls whose job is to keep fluid on one side and light guides, imaging components and angulation mechanics on the other. The leak test asks a single question before liquid is introduced: is that seal still intact? When it is not, the wet cycle that follows drives fluid into spaces designed to stay dry, and two consequences follow at once. The instrument takes damage that is often costly and sometimes permanent, and the fluid ends up in a compartment that no stage of the cycle can clean, disinfect or rinse.
That is why the test heads the sequence instead of living in the maintenance schedule. On the Detrowash 6000-8000 series, automatic leak testing sits among the control parameters that stay active through the process and detects small leaks in the endoscope, rather than issuing one verdict at the door. The distinction is practical: a seal that passes at the start of a run is not guaranteed to hold through it, and a leak found afterwards is a leak found too late.
Cleaning is a channel problem, not a surface problem
The exterior of an endoscope is the easy half of the job. The channels are the reason the equipment exists. They are long, narrow, invisible from outside and shaped so that solution touches every internal surface only if it is actively driven through each lumen. During the cleaning stage the device connects to those channels and moves detergent solution through them alongside the outer surface, at a flow it repeats the same way on every run.
Repeatability is the real contribution. A trained person can clean a scope well; what is hard is cleaning it the same way at the end of a long list as at the start of it, with brushes and syringes, in a unit under time pressure. Building an endoscope washer disinfector around channel connection and controlled flow is what converts that variable into a fixed one, which is also why the connection set matters more than the size of the chamber.
The stage does not delete the work that happens before the scope reaches the chamber. Detro Healthcare positions its reinforced enzymatic cleaner, Detro Enzym Plus DW and its 5 different enzymes, for the pre-cleaning of flexible endoscopes used in Detrowash devices, which places that step ahead of the machine cycle rather than inside it. The company’s own decontamination guidance also keeps delicate items such as telescopes, fibre optic light cables, trocar caps and seals on a careful manual route, cleaned with near neutral pH water and detergent, handled gently enough to avoid knocks and drops, and brushed only with brushes that are single use or properly reprocessed after every use. Automation narrows the range of human variation inside the cycle; it does not remove the human steps around it.
Disinfection has a limit, and the cycle does not hide it
Once the instrument is clean, the disinfection stage has to bring a high level disinfectant into contact with every surface just cleaned, exterior and lumen alike, under the conditions the cycle is built to hold. Detrowash devices are intended for heat sensitive flexible endoscopes after use, and that is precisely the group of instruments a heat based process would ruin, so the chemical route here is a consequence of what the instrument is made of rather than a preference.
High level disinfection is not a quiet stand in for sterilisation, and the manufacturer’s guidance draws that line without hedging: any doubt at all over whether a scope has been sterilised keeps that scope out of service until the process has been repeated. A correctly running cycle gives a unit a reproducible high level disinfection result. It does not promote that result into something stronger, and no amount of automation changes which category the process belongs to.
One structural detail shapes how this stage gets specified. The machines and the chemistry that runs through them come from the same manufacturer here, and the orthophthalaldehyde based Detro OPA is described as suitable both for manual use and for washer disinfectors. Which product a given cycle may run is still settled by the device instructions, not by the breadth of a range.
Rinse water decides how much of the cycle survives
Rinsing looks like the least interesting stage on the list and is the one most capable of undoing the rest of it. It carries two jobs: clear disinfectant from surfaces and channels, and do that without introducing anything new. The second job is where units get caught, because the rinse is the last liquid to touch the instrument. Whatever the water carries, the endoscope carries out of the machine.
Detro Healthcare frames the requirement around the instrument rather than the plumbing. Water used in rinsing must be of a microbiological quality appropriate for the endoscopes being processed, and for bronchoscopes and all invasive endoscopes it must be bacteria free water, meaning sterile or filtered. That makes water quality a per load question. A unit whose schedule includes bronchoscopes cannot treat the rinse supply as a background utility, because the most demanding instrument in the list sets the standard the water behind the machine has to meet.
This is also why water treatment belongs inside the device instead of being left to the building. The Detrowash 6000-8000 series carries an advanced water filter system that filters the water it uses under optimum conditions, which the manufacturer ties directly to the disinfection effectiveness of the cycle, and the Detrowash 5000-7000 series can be specified with a U/V system that disinfects the mains supply. Mains water is not a constant quality, so the control point that counts is the water at the moment it enters the endoscope, not the water as it entered the hospital.
A device that cannot disinfect itself becomes part of the circuit
Every wet cycle leaves the machine wet. Pumps, lines, connectors and the chamber hold water after the endoscope has been taken out, and any circuit that stays wet between runs is a candidate to become a reservoir that feeds the next load. Detro Healthcare is direct about the consequence: a device used in this process has to be capable of disinfecting itself, and self-disinfection appears among the published features of the Detrowash 5000-7000 series.
It is worth being precise about what that means, because the phrase is easy to misread. Self-disinfection is not wiping the outside of the unit or cleaning the chamber between loads. It is a function of the device that treats its own internal water path, which is the one part of the process staff cannot reach, inspect or correct by hand. A unit without such a function is depending on an assumption that nobody can verify from the outside, namely that the machine stays cleaner than the instruments passing through it.
Drying protects everything that came before it
Water left in a channel after reprocessing is not a cosmetic problem. It supplies the condition any organism that survived the earlier stages would need in order to multiply, and it does so during storage, when the instrument is out of sight and nobody is checking on it. Drying is therefore not the tidy up at the end of a cycle. It is what defends the result of every stage before it, over the hours when no one is watching.
Keeping that inside the machine rather than after it also keeps it off the shoulders of whoever is next in the room. The Detrowash 6000-8000 series is described as completing its washing and disinfection processes without the need for an additional drying step, leaving the endoscope ready for use as it comes out of the chamber. Where drying is handled as a separate manual task instead, it turns into one more part of reprocessing that bends with workload and attention.
What a validated cycle proves, and what it does not
Automation is only useful if the cycle can be checked, and two different kinds of evidence are involved. The first covers the cycle as a design. Detro Healthcare reports that microbiological studies and EN 15883-1, 4, 5 validation tests confirm the cycle accuracy and disinfection performance of the Detrowash 6000-8000 series, and that cycle accuracy for the Detrowash 5000-7000 series was confirmed by accredited laboratories, with the same EN 15883-1, 4, 5 tests completed successfully under disinfection conditions.
The second kind of evidence concerns a specific run. Automatic leak testing on the Detrowash 6000-8000 series operates through the process rather than at one point in it, and the Detrowash 5000-7000 series can be fitted with an optional flow sensor system that follows liquid flow so passage through the endoscope can be monitored. Keeping the two apart is worth the effort: validation describes what a cycle achieves under test conditions, while in process monitoring is what tells a unit whether this instrument, on this run, actually received what the validated cycle describes.
Questions a unit can put to its own cycle
Most reprocessing failures trace back to a stage, which makes the cycle a working checklist rather than a diagram on a wall. The useful questions map onto the stages one for one.
- Does the leak test act through the cycle, or does it only produce a verdict before the cycle begins?
- Are the channel connections correct for every endoscope model the unit actually processes, so that no lumen goes unperfused?
- Is rinse water quality set by the most demanding instrument on the list, given that bronchoscopes and all invasive endoscopes call for bacteria free water?
- Does the device disinfect its own water path, and how often is that function meant to run?
- Do endoscopes leave the chamber dry, or is a separate manual step quietly covering for the cycle?
- Is there validation evidence to EN 15883-1, 4, 5 for the configuration the unit runs, and is there anything that shows what happened on an individual cycle?
None of these questions has one correct answer that travels between hospitals. What a unit is able to run is fixed by three sources that have to agree with each other: the device instructions for use, what the endoscope manufacturer accepts for that model, and the local infection control policy in force on the ward. Where those three disagree, the reprocessing cycle is the wrong place to improvise a compromise.
