Cleaning surgical instruments is a multi-step process that moves from immediate rinsing at the point of use through manual or mechanical washing, inspection, and finally sterilization. Every step matters because organic debris left on an instrument, even in microscopic amounts, can shield bacteria from sterilization and lead to surgical site infections. The process follows a consistent sequence regardless of the facility: pre-clean, transport, wash, rinse, inspect, and sterilize.
Why Risk Category Determines the Process
Not every instrument needs the same level of treatment. The widely used Spaulding classification system sorts medical devices into three tiers based on infection risk. Critical items, those that enter sterile tissue or the bloodstream (scalpels, forceps, implants), must be fully sterilized. Semi-critical items, those that touch mucous membranes or broken skin (laryngoscope blades, some endoscopes), require at minimum high-level disinfection. Noncritical items that only contact intact skin (blood pressure cuffs, stethoscopes) need only low-level disinfection.
Surgical instruments almost always fall into the critical category. That means thorough cleaning followed by steam sterilization is the standard path. Cleaning is not optional before sterilization: residual blood, tissue, or bone fragments can insulate microorganisms from the heat or chemicals meant to destroy them.
Pre-Cleaning at the Point of Use
Cleaning starts in the operating room, not in the sterile processing department. As soon as instruments are no longer needed during a procedure, they should be wiped free of gross soil and kept moist. Dried blood and tissue are far harder to remove later. Many facilities use enzymatic spray foams or moist towels to keep instruments from drying during transport.
Instruments should then be placed in a closed, leak-proof container for transport to the decontamination area. Keeping them contained protects staff from sharps injuries and prevents contamination of hallways and elevators. For ophthalmic instruments specifically, the American Society of Cataract and Refractive Surgery recommends that all instruments opened for a procedure be transported in a closed container and cleaned separately from non-ophthalmic instruments to reduce the risk of toxic anterior segment syndrome (TASS).
Manual Cleaning Steps
Once instruments arrive in the decontamination area, the first step is a rinse in cool water. Cool water is important because hot water coagulates proteins like blood albumin, essentially baking them onto the instrument surface. After the initial rinse, instruments are submerged in a cleaning solution and scrubbed.
The choice of cleaning solution depends on the type of soil. Neutral or near-neutral pH detergents are the most common because they clean effectively without corroding metal. Many of these contain added enzymes: proteases break down blood and pus, lipases dissolve fats, and amylases handle starches. Alkaline-based cleaners dissolve protein and fat residues more aggressively but carry a higher risk of corroding instruments, so they’re used more selectively.
When scrubbing by hand, keep instruments submerged to avoid splashing contaminated material. Pay special attention to hinges, box locks, serrations, and ratchets where debris hides. For instruments with lumens (hollow channels), brushes must be long enough to pass all the way through and exit the other end, with bristles that contact the inner wall without collapsing or scratching. Single-use brushes are ideal; reusable ones need decontamination at least daily. Cleaning solutions should be changed before they become visibly soiled or drop below the temperature specified by the manufacturer.
Mechanical and Ultrasonic Cleaning
Manual cleaning alone is often not enough. AORN guidelines recommend mechanical methods, such as ultrasonic cleaners or washer-disinfectors, unless the instrument manufacturer specifically says otherwise. Mechanical cleaning is more consistent than hand scrubbing and reaches areas that brushes can miss.
Ultrasonic cleaners work through cavitation: high-frequency sound waves create millions of tiny bubbles in a liquid bath that implode on contact with instrument surfaces, dislodging debris at a microscopic level. For surgical instruments, frequencies between 36 kHz and 42 kHz are the standard range. Instruments should be placed in the ultrasonic bath with hinges open and disassembled when possible so all surfaces are exposed. The fluid in the bath needs regular replacement, at minimum daily, to prevent recontamination.
Washer-disinfectors automate the entire wash-rinse-thermal disinfection cycle. They’re the workhorse of most sterile processing departments, handling large volumes of instruments with reproducible results. After either ultrasonic or washer-disinfector processing, instruments still need a final rinse and inspection before moving to sterilization.
Rinsing and Drying
Thorough rinsing removes both soil and cleaning chemical residues. This step is easy to underestimate, but leftover enzymatic detergent on an instrument can cause tissue reactions in the next patient. For ophthalmic instruments, this is especially critical: each phaco and irrigation-aspiration handpiece should be flushed with 120 ml of sterile distilled or deionized water through both ports after every case. The enzymatic detergent and other active ingredients must be removed with pressurized sterile water.
After rinsing, instruments with lumens should be dried using forced or compressed air to prevent moisture from harboring bacteria. Flat instruments can be dried with lint-free cloths. Any remaining moisture inside a wrapped instrument set can compromise the sterilization cycle and create wet packs that are considered non-sterile.
Inspection Before Sterilization
Every instrument should be visually inspected under good lighting before it goes into a sterilizer. You’re looking for visible soil, staining, corrosion, pitting, cracked insulation, and proper function (scissors should cut cleanly, hemostats should lock at every ratchet position). A magnifying lamp helps catch fine debris in serrations and box locks.
For facilities that want objective verification beyond visual checks, residual protein testing offers a measurable standard. Ninhydrin-based tests, referenced in international standards like EN ISO 15883, detect leftover protein on instrument surfaces. These tests provide a binary pass/fail result: protein above the threshold means the instrument goes back through washing. They’re particularly useful for validating that a cleaning process is working consistently over time.
Sterilization
Steam sterilization (autoclaving) is the preferred method for most surgical instruments. It’s reliable, fast, nontoxic, and well understood. Instruments are assembled into trays, wrapped or placed in rigid containers, and loaded into the autoclave following the manufacturer’s instructions for temperature, pressure, and exposure time.
Heat-sensitive instruments that can’t tolerate steam may be sterilized with low-temperature methods such as ethylene oxide gas or hydrogen peroxide gas plasma. These take longer but protect delicate components like fiber optics or battery-powered handles.
The inside of the autoclave itself requires maintenance. The water reservoir of steam sterilizers should be changed at least weekly, and the chamber should be cleaned regularly to prevent mineral buildup that could deposit on instruments or interfere with sterilization efficacy. Properly sterilized and packaged instruments can maintain sterility for up to 90 days when packaging integrity is preserved, per ANSI/AAMI ST79 standards.
Special Considerations for Delicate Instruments
Ophthalmic instruments deserve particular attention because contaminants invisible to the naked eye can trigger TASS, an acute inflammatory reaction in the eye that can cause permanent vision loss. Beyond the separate cleaning and flushing protocols already mentioned, staff should never touch intraocular lens tips, cannula tips, or any surface that enters the anterior chamber with gloved fingers. Both powdered and powder-free gloves can leave residues capable of triggering the syndrome.
Microsurgical instruments, laparoscopic tools, and powered equipment each come with manufacturer instructions for use (IFUs) that may specify particular cleaning agents, water temperatures, or disassembly steps. These IFUs are not suggestions. They’re validated processes, and deviating from them can void the manufacturer’s guarantee that the instrument can be safely reprocessed. Keeping a current library of IFUs and training staff to follow them is one of the most practical things any facility can do to reduce reprocessing failures.
Common Mistakes That Compromise Cleaning
- Letting instruments dry before cleaning. Dried bioburden is exponentially harder to remove. Keep instruments moist from the moment they leave the sterile field.
- Using hot water for the initial rinse. Hot water coagulates blood proteins onto metal. Always start with cool water.
- Skipping lumen flushing. Hollow instruments harbor debris that external washing can’t reach. Every channel needs to be flushed through its full length.
- Reusing soiled cleaning solutions. As detergent solutions accumulate organic material, their cleaning power drops and they can redeposit soil onto instruments.
- Rushing inspection. A visually clean instrument is the minimum requirement before sterilization. If you can see residue, the sterilizer won’t fix it.