Domain III Study Guide — Indigo Field Guide

1Start here

One framework runs the whole domain.

Almost everything here flows from the Spaulding classification — how an item is reprocessed depends on what it touches. Add surface asepsis, receptor handling, and PPE, and you've got it. Baseline rule: standard precautions — treat every patient as potentially infectious.

2The framework

Critical → Sterilize
Semi-critical → Sterilize / high-level
Noncritical → Intermediate / low-level

Critical = penetrates soft tissue or bone (surgical instruments) → must be sterilized. Semi-critical = touches mucous membranes but doesn't penetrate → sterilize or high-level disinfect. Noncritical = touches only intact skin → intermediate- or low-level disinfect.

3Spaulding in radiography

What each item actually needs.

Film holders / XCP positioning devices→Semi-critical → heat-sterilize between patients

Digital sensors & PSP plates→Semi-critical, but can't be heated → barrier + intermediate-level disinfectant

PID, tubehead, exposure button, chair→Noncritical → barrier, or intermediate-level disinfect

4Surface asepsis

Barrier it, or clean-and-disinfect.

Clinical contact surfaces (touched during care)→barrier, or clean + EPA-registered intermediate-level (tuberculocidal) disinfectant

Housekeeping surfaces (floors, walls)→low-level detergent / disinfectant

Disinfect with the spray-wipe-spray (or wipe-discard-wipe) method. Barriers are changed between patients; the surface under an intact barrier doesn't need disinfecting.

5Receptor workflow

The barrier envelope is the primary infection control for sensors/PSP.

Transport exposed receptors in a cup or paper towel; touch clean surfaces only with a clean overglove.

Never autoclave or immerse a sensor/PSP — heat and chemicals destroy it.

6PPE order

Don: gown → mask → eyewear → gloves.

Doff: gloves → eyewear → gown → mask.

Gloves are last on, first off.

7Hand hygiene

Wash before gloving and after glove removal — gloves are not a substitute.

Alcohol rub is fine if hands are not visibly soiled; wash with soap and water if they are.

8Sterilizer monitoring

Biological (spore) test weekly — the only proof sterilization actually worked.

Chemical/process indicators on each load show it was processed, not that spores died.

9Agencies & exposures

Who does what.

OSHA→worker safety — the Bloodborne Pathogens Standard (protects staff, not patients)

CDC→guidelines/recommendations (2003 & 2016) — not enforceable law

EPA→registers surface disinfectants

FDA→devices + high-level disinfectants / liquid sterilants

Needlestick / exposure→wash with soap & water first, then report per the exposure-control plan

The ADA is not a regulator — it's a professional association (a classic wrong-answer trap).

10Most-missed traps

Where Domain III points get lost.

"How to reprocess a digital sensor"→barrier + intermediate disinfectant — never heat

"XCP / film holder classification"→semi-critical → sterilize

"Who registers surface disinfectants?"→EPA (FDA clears high-level disinfectants)

"OSHA protects the ___"→worker, not the patient

"Proof the sterilizer works"→weekly spore (biological) test

Domain III in 7 lines

✓ Spaulding: critical → sterilize · semi-critical → sterilize/high-level · noncritical → intermediate/low-level.

✓ Radiography: holders/XCP = semi-critical (sterilize); sensors/PSP = semi-critical but barrier + intermediate disinfect (no heat); PID = noncritical.

✓ Surfaces: clinical contact → barrier or EPA intermediate-level; housekeeping → low-level.

✓ Receptors: barrier envelope is primary; never autoclave/immerse a sensor.

✓ PPE: gown-mask-eyewear-gloves on; reverse off. Wash before gloving and after removal.

✓ Monitoring: weekly spore test proves sterilization.

✓ Agencies: OSHA workers · CDC guidelines · EPA surfaces · FDA devices/high-level · ADA not a regulator.