How to Load a Medical Automatic Washer

With the increase of complicated medical devices, central service departments (CSDs) face challenges like this one posted on a CSD chat room: “Is it acceptable to wash instrument sets through the washer in the rigid containers with the lids on? Or should the lids at least be taken off? And how much handwashing should be done before processing? I am told that our operating room (OR) cleans and washes its own instruments and then sends them down to us in CS to sterilize, run the sets through the washers in the containers with the lids on. To me, this just doesn’t sound as if the instruments would be getting cleaned.”1

An example of instrument trays entering the automatic washer, all inner trays enclosed in the container with lids securely fastened and stacked on top of each other.

An example of instrument trays entering the automatic washer, all inner trays enclosed in the container with lids securely fastened and stacked on top of each other.

Every CSD has issues with dirty instruments. The difficulty has increased, however, as surgical instruments and surgical instrument cases have gotten more complex, creating a greater challenge to the cleaning process. Research shows that dirty medical devices are a real problem:

16 percent of loaner instruments tested positive for blood2

When placing the tissue protector on the drill, old dried blood and tissue came out3

Particles of tissue were found in cannulated instruments4

There are eight factors that affect the cleaning process:

1. Soil type

2. Medical device design

3. Water quality

4. Water temperature

5. Chemical activity of the cleaning solution

6. Mechanical action

7. Human factor (loading and training)

8. Verification

One of the main reasons for the aforementioned problems is that the instruments are not being exposed and rinsed properly during the cleaning process. The focus of this article is to look at the human factor – and the impact of how surgical instruments are loaded into a medical automatic washer (MAW).

Sources of Guidance

Many times, instruments are just processed without separating or exposing the instruments completely to the cleaning process.

Instruments placed in a washer as is.

To reduce the problem of poor loading we need to look at the various sources that reference loading as a factor in the cleaning process:

Instrument manufacturers

MAW manufacturers

Standards and guidelines

Current literature

Instrument Manufacturers

Almost every surgical instrument catalog contains information in their annex similar to this:

“Yellow-brown discoloration – cause: this may be protein residuals, improperly cleaned surfaces, proteins left on the surface for a long period of time and then not thoroughly cleaned.”5

“With manual orthopedic surgical instruments, automated cleaning may not be effective. A thorough, manual cleaning process is recommended. Where applicable, disassemble instruments prior to cleaning.”6

“After surgery, open all box locks and disassemble instruments with removable parts. This will limit blood drying on instruments that may cause them to corrode. ”7

One of the most comprehensive instructions can be found at the Smith and Nephew Web site at The following are excerpts from their site:8

Cleaning is dependent upon thorough coverage of the device and the force of the water spray. Therefore, all sections of the device must be accessible for ease of cleaning and penetration of cleaning agents.

When cleaning instrument sets, the case and instruments are treated as separate items. For automatic washing, devices that have challenging design features (see “Cleaning Categories in instructions”) must be cleaned separately from the instrument case.

Automatic washing: Dried-on soil is difficult and sometimes impossible to remove with automatic washing, especially at challenging design features on devices like cannulas, interfaces, crevices, joint, hinged/mating surfaces, etc. The removal of gross soil from these areas prior to washing in the automatic washer is critical for achieving adequate cleaning.

Load the instruments in the washer such that all design features of the device are accessible to cleaning and such that design features that might retain liquid can drain (for example, hinges should be open and cannulations and holes positioned to drain).

Run the automatic wash cycle — minimum cycle parameters:

5-minute cold prewash

5-minute enzyme wash at 43 degrees Celsius minimum temperature

5-minute detergent wash at 55 degrees Celsius minimum temperature

1-minute rinse at 45 degrees Celsius minimum temperature

Check instruments for visible soil (see “Verifying Cleaning in instructions”). Repeat cleaning if soil is visible.

Some companies even tell the user that their instruments in certain cases should not be exposed to a medical automatic washer: “Standard spray type washer/disinfectors are not recommended for devices in graphic cases as the spray generally cannot penetrate the graphic case with the requisite pressure to be effective.”9 This company also states that “the user is responsible for validating their specific cleaning using their specific equipment.”10 This raises the question, how many hospitals are really verifying their cleaning process and know their sonic, medical automatic washer and their manual process is really doing the job?

Regarding tray design, here are some pointers:11

Rounded corners and modern, space-age looks also are permeating designs.

Manufacturers say their original equipment manufacturers (OEMs) want delivery systems that will catch a surgeon’s eye when a sales representative walks into the doctor’s office.

Even if an OEM has spent millions developing implants, the first thing the surgeon is going to see is the delivery system.

Aside from aesthetics, the most important factor is how well the system performs in terms of facilitating effective sterilization.

Sterilization is probably the most important consideration in designing a system. You want to make sure the cases and instruments inside are sterile.

This list of considerations suggests that the designers of these complicated trays may not be adequately concerned about the challenge to proper cleaning, but rather are focused primarily on the sterilization cycle. For example, holes that will allow steam penetration may still prevent the cleaning solution and rinse water from reaching the inner compartments of the tray.

Manufacturers of MAWs

Manufacturers of the MAW are instructing CSD professionals on proper preparation and the loading of instruments into their equipment. That information can be found in their user manuals and white papers:

“Over recent years, there have been growing concerns about the effectiveness of decontamination techniques for reusable medical instrumentation in healthcare facilities... another concern is for the safety of the healthcare workers handling products potentially contaminated with bloodborne pathogens.”12

“A low-level disinfection process is required to ensure the protection of hospital staff handling the items during the re-assembly, preparation, and packing for sterilization.”13

Ensuring the MAW is working properly and staff understands how to load instruments into the MAW is crucial to achieving the goal of surgical instruments that are safe to handle and assemble.

Tips for loading surgical instruments:14

Open all instruments, especially clamps

Keep spray arms free from obstructions

Keep instruments in a basket; avoid overloading a basket

Do not allow items to protrude outside confines of the rack

Incorrect basket loading/overloading could lead to serious personal injury and/or costly damage.15

Improper loading can be both a safety factor for staff and patients as well as causing damage to surgical instruments if not done properly according to the manufacturer’s recommendations.

Standards and Guidelines

Standards and guidelines from the various standards bodies, including the Association for the Advancement of Medical Instrumentation (AAMI), the Association of periOperative Registered Nurses (AORN), and the American Society for Testing and Materials (ASTM), are clear on the importance of cleaning and cleaning correctly:

“Most sterilizer failures result from inadequate cleaning of the instruments before sterilization.”16

“Instruments should be kept free of gross soil during surgical procedures. (PNDS; 170,198)”17

Statements like these testify to AORN’s strong commitment to the proper cleaning of instruments. AAMI ST 79 states that medical devices should be disassembled in order for all surfaces to be exposed to the cleaning process.18 AAMI TIR 12 states that manufactures should instruct medical facilities on the proper method for preparing instruments for reprocessing. These same groups also support the use of quality improvement programs to help ensure that the cleaning process is effective.

Current Literature

Exposure of the instruments to the mechanical action of the washer is important in having clean and safe instruments to handle, and the literature on this subject supports this general statement. A recent CSD article explains that tray selection has a direct correlation on the ability of instruments to get clean by means of a MAW.19

We also know from published articles ( that water quality,20 detergent, mechanical failure of the dosage system,21 and basic equipment maintenance are major factors to optimal performance of washer disinfector equipment. All must be working properly for any item to be cleaned properly.22-23 Also, if the MAW process is not independently verified in some way there is no way to know if other factors have impacted the cleaning process.

In 1969 Perkins wrote the following on loading: “... when assembling instruments in a tray for processing, care should be exercised to guard against overloading. Jointed instruments with box locks should be opened wide to expose the maximum surface area. Sharp instruments should be carefully spaced in the tray in order to prevent contact with the easily damaged surfaces. The instruments are stacked less than three inches high, which is considered maximum for optimum cleaning, rinsing, and drying. Use care to ensure that stainless steel instruments are not mixed with aluminum, or with brass or copper. Also be certain that detergents used in the cleaning process are not harmful to the instruments.”24

In the eighth edition (2004) of Proper Maintenance of Instruments, published by the Instrumentation Preparation Working Group in Germany, it is suggested that when using machine-based processes, the following should be observed:

To ensure effective cleaning, all trays, inserts, holders, etc., must be loaded correctly.

For the same reason, all articulated instruments must be processed in the open position

Avoid overloading trays to ensure that all instrument surfaces can be readily accessed by the cleaning/disinfecting solutions.

When placing large instruments on trays, make sure that they do not obscure other instruments thus preventing proper cleaning.

Instruments with cavities or hollow spaces (such as shafts, tubing, hoses, and respiration systems) need careful cleaning and rinsing on the inside as well. For this purpose, special (instrument-specific) inserts with appropriate rinsing facilities should be used.

The instruments must be arranged in such a way to prevent mechanical damage through contact.

The role of the MAW is to make sure items are safe to handle at the next stage in the process. If instruments are not exposed to the process there can be concerns. The International Association for Health Care Service Materiels Management (IAHCSMM) technical manual points this out: “Washer-decontaminators help reduce the handling of contaminated articles by central service employees which, in turn, limits their exposure to biohazards.”25

This statement supports exposing the instruments to the cleaning process and following manufacturers' guidelines: “The instruments should be placed on instrument carriers (trays) suitable for machine-based cleaning, thereby helping to ensure that they will be properly washed and rinsed. Effective cleaning requires that articulated instruments (such as scissors, clamps, and forceps) be processed in the open position to minimize surface overlapping. Complex instruments must be taken apart for cleaning in accordance with the manufacturer’s instructions.”26

Steve Johnson, a CSD manager, wrote, “... in order to ensure adequate mechanical cleaning, you must avoid excess density in each basket, as well as over stacking many baskets...prepare instrument washer loads by opening instruments box locks, organizing washer baskets to keep sets from being mixed and arranging the baskets to ensure all items come in contact with detergent and spray action...”27

Solutions to Poor Loading

To decrease the frequency of poor loading practices and its impact, medical facilities need to employ solutions based upon sources of help:

Stringing of instruments

Verification of the process

Education and training

From the OR


From the OR

“The first steps in proper reprocessing cycle are taken in the operating theatre.”28 The condition in which instruments are sent back is important. Are the instruments in the “open position,” are they “‘soaking in a solution,” have they been “wetted or sprayed with something?” The condition of instruments returned to decontamination plays a major role in the successful cleaning of the instruments. The length of time an instrument waits to begin the cleaning process can be a problem; this could be called decontamination holding time (DHT). Cooperation from the user of the instruments is important; how they send the instruments to be cleaned can add time to the process.

Actual instruments being returned to be processed after surgery (notice the blood on the drill handle,not even wiped off after use).







In recent years we have seen an increase in the use of sprays and gels to help break down the various bioburden found on surgical instruments. One reason is the DHT factors; it could be minutes to hours and even days in some cases when instruments actually get processed. These types of products help in keeping the instruments moist and usually include hydrolyzing enzymes which begin the process of breaking down blood and other soils. In fact sprays and gels have replaced the more traditional method of placing a wet cloth over instruments after surgery.

In its recommended practice, AORN clearly supports the wiping down and the proper preparation of instruments after use. Here are just a few points: “All instruments opened on the sterile field require decontamination... instruments should be prepared for decontamination after use. Instruments should be taken apart and arranged in an orderly fashion in mesh bottom trays... open instruments' box locks... cover instruments with a damp towel, at a minimum, to prevent drying during transportation to the decontamination area...”29

If surgical instruments are not returned in the proper way it will take the decontamination staff longer to prepare them for the cleaning process. If you do not take the time on the front end of the process that time has to be made up some place and that some place is usually the department that does the cleaning, assembly and sterilization of those instruments.


Stringing instruments for decontamination is an important step. This exposes instruments to the complete cleaning process. Evidence of the benefit of stringing comes from these comments by a CSD manager, “We did implement the re-stringing of instruments prior to placing in the washer. This reduced the number of lost instruments, assembly of sets was easier and best of all, we had clean instruments!”30

Other medical facilities are also seeing the benefits of stringing instruments and exposing them to the cleaning process. At a recent Greater Detroit central service meeting, Randy Sprouse, manager of central processing at Beaumont Hospital in Royal Oak, Mich., informed the audience that his medical facility not only restrings instruments (opens instruments to at least six inches, when possible) in the decontamination area but they also count them. His findings have shown an improvement in not only the cleanliness of the instruments but a reduction in instrument loss and quicker assembly and turn-around time.31 Stringing can reduce the stacking of instruments, and can also make the assembly process smoother.


Instrument stringing (top photo), positioning instruments in the tray (middle photo), proper exposure of instruments in the medical automatic washer (bottom photo).















CSD professionals challenge their sterilizer with a biological indicator (BI); on multi-layer trays many place an indicator on each level to insure sterilization has taken place throughout the tray. It is with that same philosophy we should approach testing the proper loading of the MAW. John MacDougall, RN, MS, past president of the Michigan Society of Central Service Professional, uses the TOSI™ as a tool to help his staff understand how to load instruments properly and verify that his equipment is meeting a standard. MacDougall states, “The TOSI™ represents what I am trying to clean, blood on a stainless steel instrument, and with a physical challenge to the cleaning process. It is a true model of what I am actually processing.”

MacDougall has used the TOSI™ to help show his staff how trays with multi-levels must be separated. The TOSI™ is first used to verify that the equipment is working by testing in an empty load. After that a multi-layer tray is processed using the same cycle parameters with the lid on and a TOSI™ on each level. Upon completion of the cycle the TOSI™ on each level is examined. Notice that the TOSI™ did not come clean on the second level. This simple exercise shows how trays with multi-layers need to be disassembled so they can be properly exposed to the cleaning process. Staff now has a visual understanding of the importance of separating multi-layer trays.

T.O.S.I. Cleaning verification test






Top level has a clean TOSI (top photo); second level TOSI is not clean (bottom photo).








Verification of the automatic cleaning process is now supported by many organizations. AAMI ST 79 states, ”The efficacy of any sterilization process, including saturated steam, depends on a consistent system for lowering and limiting bioburden before sterilization. Appropriate documentation and reporting practices that enable traceability of each facility-sterilized medical device to the patient on whom it is used.”32 This is just one of the many statements throughout this document that supports verification of the cleaning process.

AORN’s Recommended Practice for Cleaning and Care of Surgical Instruments and Powered Equipment Recommendation XXII – Quality section is now supporting the testing of mechanical instrument washers before initial use, weekly during service, and after major maintenance. The Joint Commission standard E.C.6.20 states that medical equipment is maintained tested and inspected.

Verifying this process is so important that medical facilities are following the recommendations of the various regulatory bodies that any simulated-use testing be done with a surrogate device that closely approximates the actual types of soils the instrument is to be exposed to in clinical use. Further, the surrogate device should be made of the same type of material as the instrument it represents. They are now making testing part of their everyday quality process improvement program.

Education and Training

Education of staff is vital to achieve the proper processing of instruments. This can only be accomplished by training, teamwork and understanding the various standards and the role they play in the cleaning process. Without training, people will not understand the need for change. Education is two-fold:

CSD: how the technician loads the instrument into the MAW

User: how the user (usually the OR) returns the instruments to be reprocessed


Make a simple checklist with the following steps:

Work with your medical automatic washer manufacturer to make sure your items can be processed in their equipment.

Understand the optimal way to use the MAW on your surgical instruments.

Involve your instrument manufacturers' and follow their instructions for cleaning.

Understand how your various cleaning solutions work.

Flow chart your process so you have a complete understanding of what is going on; different instruments might require different processes, (i.e., orthopedic might be processed differently than general or eye instruments)

Expose as much of the instrument as you can to the MAW cleaning process (open those box locks), take apart instruments as directed

Disassemble all instruments and expose them to the cleaning process (manual or automatic)

Monitor your process with quality improvement tools that will help solve and reduce current or future problems

Do not stack instruments on top of each other. Stringing of the instruments in an open position in the decontamination area is a better method

Look at new products to help expose instruments to the cleaning process; notice the exposure of the instruments when using a six-inch stringer over a two-inch stringer

Use the proper type of rack to load instruments into the MAW

Use the equipment for processing instruments

Conduct yearly in-service for all employees

Use cleaning verification products as an independent challenge to your process to ensure your equipment and your staff are working properly

Involve all of your customers in the process by explaining the important role they have in proper preparation of instruments for reprocessing

Combine all of the information from the various sources and adapt them to your process (instrument, cleaning solutions, equipment...) to load the trays correctly


Easy Stringer and six-inch wide stringer (notice the difference in the exposure of the instruments from 2 to 6 inches)












This system shows how the positions of the magnets will decide the type of cycle the instruments will be processed at.














This is an example of a bar code type system for programming.






An example of poor use and loading of equipment in a MAW.












Proper way to expose instrument to the cleaning process of a medical automatic washer; all instruments in the open position, entering the automatic washer.



“Washers can only be effective when they are properly used, loaded, and serviced in compliance with the manufacturers’ recommendation.”35 These are words to live by for every CSD. As this article has demonstrated, implementation of current standards; close adherence to instructions from device manufacturers; comprehensive routine education and training of staff; and a program of quality checks including independent verification of the cleaning process are the keys to achieving proper loading of the MAW. The result will be a dramatically reduced incidence of dirty instruments. This in turn will provide better patient care and a better and more efficient CSD.

Stephen M. Kovach is director of education for Healthmark Industries in St. Clair Shores, Mich. Kovach is educational chairperson for the AORN Specialty Assembly for SP/MM. He is a member of AORN Lakeshore Chapter 2307, a member of IAHCSMM, and his State Central Service professional group MSHCSP, and is on many AAMI standards committees.


1. IAHCSMM Forum; post 7; April 18, 2007, washing instruments in a container.

2. AORN J. March 2007. Vol. 85, No. 3; page 566.

3. Pennsylvania Patient Safety Authority 2006. Page 1.

4. Pennsylvania Patient Safety Authority 2006. Page 1.

5. Pilling Weck Surgical-Lit.99-1007. 1/99; 17M; page 364.




9. Coatesworth letter from SYNTHES®; Request for Cleaning Parameters. Nov. 23, 2004.

10. Ibid.


12. Technical Data Monograph: Decontamination of Reusable Medical Devices using FAST Cycles on Reliance®Synergy™ Washer/Disinfectors. STERIS®. Aug. 1, 2004.


14. AVENATECH, Inc. Washer/Decontaminators – In-Service Training Guide-Operation of The Belimed SM-100. Pages 18-19. 1998.

15. RELIANCE®777, Equipment Manual; 9/1/91-Rev2.

16. AORN Perioperative Standards and Recommended Practices, 2008. Page 423.

17. AORN Perioperative Standards and Recommended Practices, 2008. Page 434.

18. ANSI/AAMI ST 79:2006

19. Recommendations by the Quality Task Group (33) Mesh Trays and their Implication for successful Cleaning in the washer-Disinfector; Zentr Steril.

20. Basile R and Kovach S. A Thorough Cleaning part 2. Managing Infection Control. February 2003.

21. Zentr Steril Forum 2004. M.Wieder. Dosage and Control Mechanism in Validation of Automatic Cleaning and Disinfection Processes.

22. Basile R and Kovach S. A Thorough Cleaning part 3. Managing Infection Control. March 2003.

23. Basile R and Kovach S. The Cleaning Process. Managing Infection Control. July 2003.

24. Principles and Methods of Sterilization in Health Sciences, second edition. Perkins. Page 250.

25. IAHCSMM. Fundamentals of Cleaning for Decontamination. Self Study Series Lesson 42.

26. Proper Maintenance of Instruments, eighth edition. 2004. Page 20.

27. Johnson S. Infection prevention: are those instruments sets ready yet? Outpatient Surgery.

28. Proper Maintenance of Instruments, eighth edition. 2004. Page 19.

29. AORN 2006 Standards, Recommended Practices, and Guidelines. Pages 555-556.

30. Personal correspondence between D. Coatsworth and S. Kovach, Nov. 12, 2007.

31. Dec. 7, 2007 Greater Detroit Central Service meeting.

32. ANSI/AAMI ST79:2006. Page 1.



35. IAHCSMM. Seventh edition Central Service Technical Manual. Page 145.

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