As a supplier of washer disinfector systems, I’ve spent thousands of hours walking alongside healthcare facility managers, sterile processing technicians, and biomedical engineers across North America and Europe. Too many times, I’ve heard the same story: a device that’s supposed to eliminate 99.999% of microorganisms leaves a set of surgical tools with visible soil, or worse, residual protein that risks patient infection. More often than not, the root cause isn’t a faulty machine—it’s improper loading. When it comes to washer disinfectors (WDs)—the workhorses of sterile processing departments (SPDs) that bridge manual cleaning and terminal sterilization—loading isn’t just a step, it’s a foundational factor in patient safety, equipment longevity, and operational efficiency. Let’s break down why getting it right isn’t just a best practice—it’s non-negotiable. Washer Disinfector
First, let’s ground this in the core function of a washer disinfector: it uses controlled temperature, mechanical action, and chemical detergents to remove bioburden (blood, tissue, debris) from reusable medical devices, a step that cannot be skipped before autoclaving or ethylene oxide (EtO) sterilization. If bioburden remains post-WD, sterilization cycles can fail—heat-resistant spores hide in soil, chemical agents cannot penetrate organic residue, and even small amounts of blood can neutralize sterilant. A 2022 study from the Association for the Advancement of Medical Instrumentation (AAMI) found that 18% of sterilization failures traced back to inadequate pre-sterilization cleaning, and improper loading was the single most common contributing factor, more than detergent concentration or cycle temperature. That statistic isn’t just a number—it’s a direct link to patient harm.
But let’s move beyond the abstract to what I see daily in SPDs. Last year, I visited a mid-sized community hospital where their 12-year-old WD had a 10% failure rate on weekly biologic indicator tests. Their SPD supervisor, Maria, told me they’d switched to a cheaper loading pattern to fit more instruments per cycle, turning a full load into a 20% overloaded stack. When we pulled the chamber after a test run, we found half the endoscopes had their distal ends blocked by forceps, so the WD spray arms couldn’t reach the internal lumens—places where biofilm thrives. That’s the problem with improper loading: it creates hidden pockets where water, detergent, and disinfectant can’t reach. Over time, those pockets accumulate not just bioburden, but also mineral deposits from hard water or dried protein, which corrode devices like surgical steel, endoscope channels, and even delicate instruments like laparoscopic cameras. I’ve seen three endoscopes replaced in two years at that same hospital, a $12,000 total cost, all traced back to overloading that trapped debris. That’s a tangible cost no budget can absorb.
Let’s unpack the science of proper loading, because it’s not just “don’t cram everything in.” Washer disinfectors rely on three key mechanical actions: spray impingement (water hitting the device surface at a specific pressure), tumbling (for porous items like drapes or labware), and water displacement (for lumens). If a device is pressed against another, spray impingement drops by 70%—a 2019 study from the International Association of Healthcare Central Service Materiel Management (IAHCSMM) confirmed that. Lumens, in particular, are a high-risk area: when a scope is loaded with its open end against a tray wall, the WD’s high-pressure rinse can’t circulate through the channel, leaving residual blood that becomes a breeding ground for pathogens like Mycobacterium abscessus, a rapidly growing mycobacterium that causes difficult-to-treat infections. The Centers for Disease Control and Prevention (CDC) has documented 12 outbreaks of M. abscessus linked to improperly cleaned endoscopes between 2015 and 2023, all tied to loading patterns that blocked lumen access.
Another critical point: device categorization. Not all reusable items are the same. The FDA classifies medical devices into three categories: critical (surgical instruments that touch sterile tissue), semi-critical (endoscopes that touch mucous membranes), and non-critical (blood pressure cuffs). Proper loading requires grouping devices by category, not mixing sharp surgical tools with flexible endoscopes, for example. Sharp tools can scratch endoscope surfaces, creating crevices that trap bioburden; conversely, endoscopes have delicate lenses and seals that can be damaged by heavy forceps. I once worked with a surgical clinic that mixed orthopedic screws with a set of laparoscopes, and during a WD cycle, a screw chipped an endoscope’s lens—an $8,500 repair, avoidable with category-based loading.
Proper loading also impacts operational efficiency, which is a top concern for every SPD manager I work with. When loading is done right, cycle times can be shortened by up to 15%, because the WD doesn’t waste energy fighting to reach hidden debris, and manual reprocessing time (the work technicians have to do to re-clean devices that failed the WD) drops by an average of 22%, per IAHCSMM’s 2024 Workload Survey. Let’s do the math: a mid-sized hospital with 10,000 reusable procedures a year, spending 10 hours a week re-cleaning improperly loaded devices, could regain 520 hours of technician time annually—time that can be redirected to quality checks, inventory management, or patient care support. For smaller clinics, that time often translates to being able to clear cases faster, reducing patient wait times for surgeries.
But here’s the thing: many facilities don’t have standardized loading protocols. I’ve visited sites where SPD techs load based on past habits, not manufacturer guidelines, and 60% of the time, those habits include overloading. That’s why as a supplier, we don’t just sell WD systems—we offer loading training, custom rack accessories, and cycle validation support. Last quarter, we trained a 30-person SPD team at a children’s hospital, and after three months, their biologic indicator failure rate dropped from 12% to 2%. The nurses there told us they’d seen fewer post-surgical infections in orthopedic patients that quarter, a direct benefit of cleaner devices. It’s a cycle of trust: proper loading reduces risk, which reduces costs, which frees up resources to invest in better equipment and training.
Now, let’s address a common myth: “We use high-end detergents, so loading doesn’t matter.” Detergents work best when they can come into contact with bioburden. If a device is hidden behind another, even the strongest alkaline or enzymatic detergent can’t dissolve blood or tissue stuck under a sharp instrument’s teeth, for example. A 2021 study from the Journal of Hospital Infection tested three leading WD detergents, finding that when bioburden was trapped between two metal tools, even 5x the recommended detergent concentration only removed 30% of the residue, compared to 98% when the tools were spaced 1 inch apart. That’s not a detergent failure—that’s a loading failure.
Long-term equipment maintenance is another key impact of proper loading. Washer disinfectors have internal components: spray arms, pumps, filters, that rely on unobstructed water flow. If racks are overloaded, debris from devices can get trapped in the spray arm nozzles, leading to clogs that require part replacements every 6 months, rather than every 2 years. We’ve had customers tell us that after switching to proper loading, their WD maintenance costs dropped by 30% annually, extending the machine’s lifespan by 3 to 5 years. For a facility that spends $50,000 on a mid-range WD, that’s a $15,000 to $25,000 savings over the machine’s lifetime.
Of course, there are edge cases: delicate devices like robotic surgical instruments, which have tiny sensors and wiring, require custom loading racks, not standard trays. Flexible endoscopes need hanging racks, not stacking, to prevent kinks in their channels. Rigid endoscopes need open trays to let spray reach all surfaces. Too many facilities use one-size-fits-all racks, which is a recipe for improper loading. That’s why we design our WD accessories to be modular—techs can swap racks for different device types, and our training program covers how to match racks to device categories.
I’ve also seen what happens when loading goes wrong on a large scale. A few years ago, a regional surgery center had a WD failure that led to a 3-month delay in 12 scheduled joint replacement surgeries, because 20% of their instruments were not properly cleaned and could not be used for sterile cases. The root cause? Their temp agency had sent a new tech who wasn’t trained on loading protocols, and they’d overloaded the chamber to get through a backlog of cases. That delay cost the center an estimated $250,000 in lost revenue, plus patient dissatisfaction—one patient even transferred to another clinic for their replacement surgery, citing concerns over the center’s infection control.
So what does proper loading actually look like in practice? From my experience on hundreds of site visits, here are the non-negotiables:
- Do not overload: Manufacturers specify a maximum fill level (usually 85% of the chamber volume) and spacing between devices (1 inch for rigid tools, 0.5 inches for delicate items).
- Group by device type: Critical, semi-critical, and non-critical items are loaded separately to prevent cross-contamination and damage. Lumens are hung or placed in lumen-specific racks to allow full water circulation.
- Secure devices: Sharp tools are placed in protective holders to prevent movement during cycles, so they don’t scratch other devices or block spray.
- Empty trays first: Loose items (screws, blades) are placed in perforated trays, not directly on chamber floors, so water can flow under them.
- Validate cycles: Regularly test a small, low-efficiency load and a full load to ensure spray and temperature are consistent across all items.
These steps aren’t complicated, but they require consistency, training, and the right equipment. That’s where we come in. As a WD supplier, we don’t just provide machines—we partner with facilities to develop loading protocols tailored to their specific needs, whether they’re a small outpatient clinic, a mid-sized hospital, or a large academic medical center. We offer on-site training, custom rack solutions, and ongoing support to make sure loading is a strength, not a weak point, in their sterile processing workflow.
If you’re looking to reduce infection risk, cut equipment costs, and improve operational efficiency in your SPD, let’s connect to discuss how proper loading can transform your WD performance. I’d be happy to walk you through case studies from similar facilities, answer questions about custom racks, or arrange an on-site walkthrough of our loading training process.
Drying Cabinet References
Association for the Advancement of Medical Instrumentation (AAMI). (2022). Sterilization and Reprocessing Guidelines for Medical Devices.
International Association of Healthcare Central Service Materiel Management (IAHCSMM). (2024). Central Service Workload and Quality Survey Report.
Centers for Disease Control and Prevention (CDC). (2023). Outbreaks of Mycobacterium abscessus Associated with Reprocessed Endoscopes, 2015–2023.
Journal of Hospital Infection. (2021). The Impact of Load Configuration on Washer Disinfector Cleaning Efficacy for Medical Devices.
U.S. Food and Drug Administration (FDA). (2020). Classification of Reusable Medical Devices for Sterilization and Reprocessing.
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