Clean and sterile technique: medical and surgical asepsis
- Fundamental
Clean technique reduces microorganisms; sterile technique removes them completely and is used when entering sterile tissue.
What it is
Medical asepsis, or clean technique, brings together the practices that reduce the number of microorganisms and slow their spread: hand hygiene, a clean environment, PPE and isolation. Surgical asepsis, or sterile technique, aims for the complete absence of microorganisms during invasive procedures; it is used in the operating room, in special procedures and at the bedside, for example when inserting an indwelling urinary catheter, caring for a central line or changing the dressing of an open wound. Sterile technique relies on fixed rules about what counts as sterile and what does not.
Key points
- Disinfection removes microorganisms but not every spore; sterilization destroys them all, spores included.
- Skin can be disinfected before a procedure, but it can never be sterilized.
- A sterile item that touches the outer wrapping or any non-sterile surface is contaminated.
- Your body and clothing are not sterile: keep them away from the field and never over it.
Components
- Medical asepsis: hand hygiene, environmental cleaning, PPE, isolation.
- Surgical asepsis: sterile field, sterile gloves, in-date and intact sterile supplies, controlled movements.
- Safe injection: aseptic technique and single-patient, single-use supplies.
What it is for
- Protecting the patient from healthcare-associated infections.
- Protecting staff and other patients.
- Keeping procedures that enter sterile cavities or tissue free of microorganisms.
Medical asepsis versus surgical asepsis
| Aspect | Clean technique (medical asepsis) | Sterile technique (surgical asepsis) |
|---|---|---|
| Aim | Reduce the number of microorganisms | Eliminate all microorganisms |
| Measures | Hand hygiene, cleaning, PPE, isolation | Sterile field, sterile gloves and supplies |
| Examples | Routine care, changing bed linen, cleaning shared equipment | Urinary catheter insertion, central line care, surgery |
In nursing practice
- Before any sterile procedure, the expiry date and integrity of every package are checked.
- The field is kept in view: if the clinician turns their back, the field is considered contaminated.
- Never reach over the sterile field.
- If a non-sterile object touches the field, or a package shows holes, tears or moisture, sterility is lost.
Common mistakes
- Leaning over the field or letting clothing touch it.
- Lowering gloved hands below the waist.
- Using a wet, torn or expired package.
- Treating prepped skin as if it were sterile.
- Carrying on after a contamination instead of replacing the supplies.
Test yourself
Think of the answer, then tap the question to see it.
How do medical and surgical asepsis differ?
Medical asepsis (clean technique) reduces the number of microorganisms; surgical asepsis (sterile technique) aims to eliminate them all during invasive procedures.
Which part of a sterile field is considered non-sterile?
The outer 2.5 cm of the field and the outside of the package. Also anything below the waist or that has been out of sight.
What happens to a sterile field that gets wet?
It is no longer sterile, because moisture lets microorganisms pass through the material.
Which bedside procedures require sterile technique?
For example, inserting an indwelling urinary catheter, central line care and changing the dressing of an open wound.
Connections
Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.
Sources: Isolation Precautions: Summary of Recommendations (Guideline for Isolation Precautions, 2007) (Centers for Disease Control and Prevention (CDC), 2007); Nursing Skills, 4.3 Aseptic Technique (Open RN, Wisconsin Technical College System (LibreTexts copy, CC BY 4.0), 2021); Nursing Skills, 4.4 Sterile Fields (Open RN, Wisconsin Technical College System (LibreTexts copy, CC BY 4.0), 2021); Nursing Fundamentals, 9.6 Preventing Infection (Open RN, Wisconsin Technical College System (LibreTexts copy, CC BY 4.0), 2021).
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Representative model, for educational purposes only.