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newSchoolWorks.com › VoTechWorks › Health & Personal Services › Surgical Technology › Sterilization: Principles and Practice in the Surgical Environment › Lesson 3
HLT-SURG65-05 · Lesson 3 · 30.5 clock hours · lab

Decontamination: Point-of-Use Treatment Through Manual and Ultrasonic Cleaning

Objective. Students will perform point-of-use treatment, manual scrubbing with enzymatic detergent, and ultrasonic cleaning of soiled surgical instruments following AAMI ST79 guidelines.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

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Why Decontamination Comes First

Every instrument that touches a patient carries blood, tissue, and body fluids. Before sterilization or high-level disinfection can work, all organic material and debris must be physically removed. Sterilants and disinfectants cannot penetrate a biofilm or soil layer, so an instrument that looks clean but still carries residue will not be reliably sterile after processing. Decontamination — the combination of cleaning and disinfection steps that reduce the microbial load to a safe level — is therefore the most critical phase of instrument reprocessing. AAMI ST79 (the Comprehensive Guide to Steam Sterilization and Sterility Assurance in Health Care Facilities) is the primary US guidance document that describes best practice for every step covered in this lesson.

Point-of-Use Treatment

Point-of-use treatment begins at the sterile field, the moment an instrument is no longer needed. The scrub surgical technologist removes gross soil — visible blood, tissue, and saline — by wiping instruments with a sterile, moist sponge and rinsing them in sterile water when available. The goal is to prevent soil from drying and hardening, which makes later cleaning far more difficult. Instruments must never be allowed to dry before reprocessing.

After the procedure, used instruments are placed in a covered, puncture-resistant container (often a closed rigid tray or a covered basin) before transport to the decontamination area. This protects both the instruments and the personnel who carry them. Sharps — including needle holders with suture needles — must be accounted for and contained safely before the set leaves the room.

Personal Protective Equipment (PPE)

The decontamination area is a restricted zone with a defined PPE requirement. Before touching any soiled instrument, personnel must don:

Removing PPE in the wrong order or leaving the decontamination area without removing soiled PPE risks spreading contamination. This is a patient-safety and worker-safety issue.

Manual Cleaning with Enzymatic Detergent

Manual cleaning follows these key principles.

Water temperature. Use water at the temperature specified in the detergent's instructions for use (IFU). Most enzymatic detergents are formulated for lukewarm water — typically around 100–110 °F (roughly 38–43 °C). Water that is too hot denatures the enzymes and destroys cleaning effectiveness; water that is too cold slows enzymatic activity.

Dilution. Mix detergent to the exact ratio stated in the IFU. More is not better: excessive concentration can leave residue that interferes with sterilization.

Brush technique. Use an appropriately sized soft-bristle brush. Scrub all surfaces under the waterline to prevent aerosol generation. Open box-lock joints fully. Scrub inside serrations, lumens, and crevices. Use pipe cleaners or lumen brushes for tubular instruments.

Rinsing. Rinse instruments thoroughly with water — the quality of rinse water matters. Hard water can leave mineral deposits. A final rinse with treated (softened or deionized) water is recommended when available.

Inspection. After rinsing, visually and functionally inspect each instrument: check that box locks move freely, scissors cut cleanly, and ratchets engage. Damaged or permanently soiled instruments are removed from service.

Document the process on a decontamination log that records the date, instrument set, operator, water temperature, detergent lot, and any instruments removed.

Ultrasonic Cleaning

Ultrasonic cleaners use a process called cavitation — the rapid formation and implosion of microscopic bubbles created by high-frequency sound waves — to dislodge soil from instrument surfaces, including areas a brush cannot reach.

Loading the ultrasonic unit. Instruments must be:

Do not mix metals (e.g., stainless steel with chrome-plated instruments) in the same load; dissimilar metals can cause electrolytic damage.

Degassing cycle. A new batch of solution contains dissolved air that inhibits cavitation. Run a degassing cycle — typically a short timed run with the lid open — before the first cleaning cycle of the day or after each solution change.

Cleaning cycle. Run the cycle for the time specified in the manufacturer's IFU. Extend the cycle only if the IFU allows; over-exposure can pit instrument surfaces.

Cavitation test (aluminum foil test). Place a small piece of aluminum foil in the energized unit for approximately 30–60 seconds per the manufacturer's IFU. Pitting and perforation of the foil indicate that cavitation is occurring. Smooth or undamaged foil signals inadequate cavitation — stop and troubleshoot before using the unit.

After ultrasonic cleaning. Remove instruments, rinse thoroughly, inspect, and lubricate hinged instruments with an instrument milk (water-soluble lubricant compatible with sterilization) before assembly and packaging.

Safety Summary

Key terms9

DecontaminationThe process of removing or reducing contamination — including microorganisms and organic material — from instruments to a level that is safe for further handling and processing.
Point-of-use treatmentGross soil removal and moisture retention performed at the surgical field immediately after instrument use, before transport to the decontamination area.
Enzymatic detergentA cleaning solution containing enzymes (such as proteases, lipases, and amylases) that chemically break down proteins, fats, and carbohydrates in organic soil on instruments.
CavitationThe formation and violent collapse of microscopic bubbles produced by high-frequency sound waves in an ultrasonic cleaner; the energy released dislodges soil from instrument surfaces.
DegassingA preliminary cycle run in an ultrasonic cleaner to release dissolved air from fresh solution, which would otherwise suppress cavitation activity.
AAMI ST79The Association for the Advancement of Medical Instrumentation's comprehensive guidance document for steam sterilization and sterility assurance in health care facilities, widely used as the US practice standard for instrument reprocessing.
Instructions for Use (IFU)Manufacturer-provided directions that specify how a device, chemical, or piece of equipment must be used; reprocessors are legally and professionally required to follow them.
Box lockThe pivot joint of an instrument such as a hemostat or scissors; a common site for soil accumulation that requires deliberate scrubbing during manual cleaning.
Instrument milk (lubricant)A water-soluble, steam-permeable lubricant applied to hinged instruments after cleaning to protect metal surfaces and maintain smooth operation through repeated sterilization cycles.
In class: Instructor demonstration of point-of-use treatment (gross soil removal, keep moist) at a simulated OR field, followed by safe transport to the decontamination area in a covered, puncture-resistant container. · Hands-on lab: students manually clean a set of mixed instruments (hemostats, scissors, retractors) using the correct water temperature, brush technique, and rinsing steps, then document the process on a decontamination log sheet. · Ultrasonic cleaner operation lab: students load an ultrasonic unit correctly (instruments open, submerged, not touching walls), run a degassing cycle, then a cleaning cycle, and test cavitation activity with aluminum foil per manufacturer IFU.
Materials: Simulated soiled instruments, enzymatic detergent (per IFU), instrument brushes, decontamination sinks, ultrasonic cleaner, personal protective equipment, aluminum foil for cavitation test, decontamination log forms, AAMI ST79
Check: Instructor observes manual cleaning technique using a 12-step performance checklist; all safety-critical steps (PPE, covered transport, correct dilution) must be correct; overall pass mark 85%.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Sterilization and Disinfection
1. What is the primary reason instruments must be cleaned before sterilization?
Sterilization and Disinfection
2. During point-of-use treatment at the sterile field, the scrub surgical technologist should:
Sterilization and Disinfection
3. Which of the following is a safety-critical requirement when transporting soiled instruments from the operating room to the decontamination area?
Sterilization and Disinfection
4. When manually scrubbing soiled instruments with an enzymatic detergent, the technologist should scrub:
Sterilization and Disinfection
5. Why is water temperature important when mixing enzymatic detergent for manual instrument cleaning?
Sterilization and Disinfection
6. When loading instruments into an ultrasonic cleaner, the surgical technologist should ensure that instruments are:
Sterilization and Disinfection
7. A scrub surgical technologist runs the aluminum foil test in the ultrasonic cleaner and finds the foil is completely smooth with no pitting after the test period. The correct action is to:
Sterilization and Disinfection
8. According to AAMI ST79, what is the purpose of running a degassing cycle in an ultrasonic cleaner at the start of the day?
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