[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Nursing](https://durgical.com/en/nursing/) › [Infection prevention and control](https://durgical.com/en/nursing/areas/infection/) › Clean and sterile technique: medical and surgical asepsis

# 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.

Updated Nov 5, 2026

## Key points

- Clean technique: reduces microorganisms. Sterile technique: eliminates them.
- Medical asepsis: hand hygiene, clean environment, PPE and isolation.
- Sterile technique at the bedside: urinary catheter insertion, central line care, open-wound dressings.
- Anything below the waist, out of sight or wet is no longer sterile.
- The 2.5 cm border of the sterile field and the outside of the package are not sterile.

## 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.

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## Connections

## Related 3

- [Setting up a sterile field and putting on sterile gloves](https://durgical.com/en/nursing/setting-up-a-sterile-field-and-putting-on-sterile-gloves/)
- [Standard precautions](https://durgical.com/en/nursing/standard-precautions/)
- [Cleaning, disinfection and sterilization of equipment](https://durgical.com/en/nursing/cleaning-disinfection-and-sterilization-of-equipment/)

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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)](https://www.cdc.gov/infection-control/hcp/isolation-precautions/summary-recommendations.html) (Centers for Disease Control and Prevention (CDC), 2007); [Nursing Skills, 4.3 Aseptic Technique](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/04:_Aseptic_Technique/4.03:_Aseptic_Technique) (Open RN, Wisconsin Technical College System (LibreTexts copy, CC BY 4.0), 2021); [Nursing Skills, 4.4 Sterile Fields](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/04%3A_Aseptic_Technique/4.04%3A_Sterile_Fields) (Open RN, Wisconsin Technical College System (LibreTexts copy, CC BY 4.0), 2021); [Nursing Fundamentals, 9.6 Preventing Infection](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Fundamentals_(OpenRN)/09:_Infection/9.06:_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.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/nursing/clean-and-sterile-technique-medical-and-surgical-asepsis/