Why Decontamination Is Critical for the CRCST Exam
Decontamination is one of the highest-weighted domains on the CRCST exam at 21%. It is also the foundation of the entire sterile processing workflow — if instruments aren't properly decontaminated, nothing that follows (packaging, sterilization, storage) will protect patients.
The Decontamination Workflow
The correct order of decontamination is:
- Point-of-use pre-cleaning — at the surgical field, immediately after use
- Transport — contained, closed transport to the decontamination area
- Sorting and disassembly — separate instruments, open all hinged instruments
- Manual cleaning — enzymatic soak, scrubbing, rinsing
- Mechanical cleaning — ultrasonic cleaner or washer-disinfector
- Inspection — check for soil, damage, and function
- Drying — forced air or lint-free cloth
- Transfer to prep and pack — through a pass-through window
Point-of-Use Pre-Cleaning
Point-of-use pre-cleaning happens in the OR, immediately after the procedure. It includes:
- Wiping gross soil from instruments with a damp sponge
- Keeping instruments moist to prevent biofilm formation
- Never using saline — saline causes corrosion and pitting
PPE Requirements in Decontamination
The decontamination area is a contaminated zone. Required PPE includes:
- Waterproof gown or apron
- Heavy-duty puncture-resistant gloves
- Face shield or goggles + mask
- Waterproof shoe covers
You must don PPE before entering the decontamination area and doff it before leaving.
Manual vs. Mechanical Cleaning
Manual cleaning is required for:
- Delicate instruments that cannot withstand mechanical cleaning
- Instruments with complex lumens or channels
- Items the IFU specifies as manual-clean only
Mechanical cleaning (ultrasonic cleaners, washer-disinfectors) is preferred when possible because it is more consistent and reduces staff exposure.
Enzymatic Cleaners
Enzymatic cleaners contain proteases, lipases, and amylases that break down organic soil. Key facts for the exam:
- Must be used at the correct dilution ratio per manufacturer's IFU
- Must be used at the correct water temperature
- Solution must be changed between each use — never reuse
- Low-foaming formula is preferred for mechanical washers
The Ultrasonic Cleaner
Ultrasonic cleaners use cavitation — the formation and collapse of microscopic bubbles — to remove soil from instrument surfaces and crevices.
Key exam points:
- Must be degassed when solution is changed
- Instruments must be fully submerged
- Hinged instruments must be open
- Run time is typically 3–10 minutes
- Solution must be changed at least daily or when visibly soiled
Common CRCST Decontamination Exam Questions
Q: What should NEVER be used to pre-clean instruments at point of use?
A: Saline — it causes corrosion and brown/orange staining.
Q: What type of water should be used for the final rinse?
A: Purified, deionized, or distilled water — to prevent water spots and mineral deposits.
Q: What is the purpose of a washer-disinfector?
A: To clean AND thermally disinfect instruments in a single cycle.
Q: What does "one-way workflow" mean in decontamination?
A: Instruments move in one direction — from contaminated to clean — and never go backwards.
Practice more decontamination questions on Sterile Processing Prep — our question bank has 48 decontamination questions mapped to the CRCST exam outline.
Official Resources
- CDC Guideline for Disinfection and Sterilization in Healthcare Facilities — The authoritative CDC reference for decontamination and sterilization
- AAMI TIR34 — Water for the Reprocessing of Medical Devices — ANSI/AAMI standards for water quality in decontamination
- HSPA Sterile Processing Technical Manual, 9th Edition — Primary CRCST study reference