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What are Different AAMI Levels of Testing Surgical Gowns?

What are Different AAMI Levels of Testing Surgical Gowns?

Before we describe various levels of AAMI levels of testing, it is important to understand what AAMI is and what is it used for.

AAMI stands for Association for the Advancement of Medical Instrumentation (AAMI), which is an organization whose standards are accepted by FDA as quality parameters for surgical or medical care operations or facilities.

This AAMI testing refers to the standard that establishes a classification system from levels (1-4) for protective apparel which is principally used in healthcare facilities based on liquid barrier information using standard testing methods.

Some of the commonly used protective apparel are:

  1. Surgical Gowns
  2. Non-surgical gowns
  3. Surgical Isolation gown

This standardization provides liquid barrier performance in the critical zones of surgical and non-surgical gowns and drapes, areas where the medical professional most probably will be in contact with potentially infectious fluids like blood and bodily fluids.

Before choosing a gown for the staff or professionals of the medical facility, care is taken that the given gown is gone through various levels of AAMI testing, ensure pure protection under all circumstances.

Three Tests for Surgical Gowns

tests for surgical gowns

As per the ANSI/AAMI PB70 standard, three standard tests are conducted. These are the following:

  1. AATCC 42 Impact Penetration
  2. AATCC 127 Hydrostatic Pressure
  3. ASTM F1671 Viral Penetration

The four levels of AAMI rating and their respective testing parameters based on above mentioned tests are-



Liquid Challenge


Expected Barrier Effectiveness


AATCC 42 Impact Penetration


= 4.5 g

Minimal water resistance


AATCC 42 Impact Penetration


= 1.0 g

Low water resistance

AATCC 127 Hydrostatic Pressure


= 20 cm


AATCC 42 Impact Penetration


= 1.0 g

Moderate water resistance

AATCC 127 Hydrostatic Pressure


= 50 cm


ASTM F1671 Viral Penetration Test (for surgical and isolation gowns)


no penetration at 2 psi(13.8 kPa)

Viral  penetration resistance  (2psi)



  1. Minimal fluid barrier protection: This is level 1 protection, which is generally used for a patient’s daily care routine, and where there is little to no risk of fluid exposure.
  2. Minimum to low fluid barrier protection: This is level 2 protection where a slight exposure to bodily fluids is present for minimalistic surgery procedures like bumps and lumps.
  3. Moderate fluid barrier protection: This is level 3 protection where a moderate level of fluid exposure is present and is used in all levels of surgery.
  4. Highest fluid and microbial protection: It provides protection against blood-borne pathogens is found critically in critical zones, during length and complex surgery procedures.

Critical Zones

It is important to know the term critical zones:

These zones are the definitive zones where a person can come in contact with the blood and infected bodily fluids. This can be easily illustrated through an infographic diagram, as given below.

critical zones of surgical gowns