Sterilisation Methods in Healthcare

Infection control is of paramount importance in the medical and healthcare industry, as well as in numerous other sectors. From basic handwashing and the use of personal protective equipment (PPE) including gloves, masks, eye protection, and more, to disinfection and adopting single-use items, hygiene is essential.

A sterile environment is essential for all invasive or potentially invasive procedures – from injections to dental procedures to surgery, all instruments used and the immediate environment itself must be sterile.

What does this mean? 

Sterility is the complete absence of any viable organism that could reproduce and spread – and it includes disease-causing pathogens like bacteria, viruses, fungi, parasites, spores, and any other microorganism or toxin.

Sterile environments are crucially important in surgeries, operating theatres, certain hospital settings, dental clinics, research laboratories, pathology settings, pharmaceutical development, and some parts of the food production industry.

What is Sterilization?

Many of the instruments used in medical, dental, pathology, and scientific research settings, as well as in sectors like the tattoo and piercing industries, drug development, and the food and beverage industry,  are not single-use.  As such, they must be sterile, used only one time, and then re-sterilised for the next patient or client.

Sterilisation is the process by which microorganisms and other potentially pathogenic biological agents are removed, deactivated, or killed.

(Disinfection eliminates all or most pathogens on non-biological objects (but does not remove bacterial spores).

Cleaning simply removes visible material from objects and is required before disinfection and/or sterilisation.

Decontamination eliminates pathogenic microorganisms so items are safe for disposal, handline, or use.)

Sterilisation destroys or otherwise inactivates all microorganisms on the surface of an instrument or other article or within a fluid. This prevents transmission of disease when the item is used.

All critical items (i.e., those that contact body fluids or body tissues) must be sterile to avoid microbial contamination and potential disease transmission. These include:

  • Surgical instruments
  • Dental instruments
  • Biopsy forceps
  • Tattooing and piercing instruments
  • Implanted medical devices
  • Laboratory instruments
  • And others

Methods of Sterilisation

Before 1950, most surgical and medical instruments and devices were heat-stable and could withstand high temperatures. Therefore, they were sterilised using high heat in the form of steam sterilisation. Over the last seventy years, however, many medical and surgical devices have evolved to be made from other materials and high heat is unsuitable for some of these. Newer forms of sterilisation have also evolved.

There are several methods of sterilisation used in healthcare facilities:

  • Steam Sterilisation uses saturated steam under pressure in an autoclave and is both the most dependable and widely used form of sterilisation in a healthcare setting. Its benefits include it being inexpensive, non-toxic, fast, and effective for killing microbes and spores. As some materials may be corrosive or otherwise unsuitable for direct steam contact, autoclave bags are used to protect the instrument or other items and keep them sterile until the moment of use. This method is preferred for sterilising all suitable equipment as well as for the decontamination of microbiological waste and sharps containers.
  • Flash Sterilisation uses a modification of the steam sterilisation process, which is incredibly fast but has limitations. It is most valuable close to operating theatres where the instrument will be immediately used and the environment is itself sterile. It is most suitable for processing previously cleaned patient care items that can’t be otherwise packaged, sterilised, and stored.
  • Gas (Ethylene Oxide or ETO) Sterilisation uses ETO gas to sterilise moisture-sensitive items or those requiring low temperatures. It has been used in one form or another since the 1950s. Explosive and flammable, this colourless gas is used for sterilisation in a lengthy process which is suitable for those items that are very moisture- or heat-sensitive. It is absorbed by many materials, so items sterilised with this method must have residual ETO removed. It can be toxic. It is only generally used in medical settings where steam sterilisation is unsuitable.
  • Hydrogen Peroxide Gas Plasma uses newer technology that was introduced in the 1990s. using a deep vacuum in an enclosed chamber, radiofrequency or microwave energy is used to produce charged particles from gas molecules that interact with cells and disrupt their metabolism. It is currently used for devices and materials that are intolerant to humidity or high temperatures, including metal alloys that are susceptible to corrosion, electrical devices, and some plastics.
  • Ionising Radiation is an effective but high-cost low-temperature sterilisation process, where a Cobalt 60 gamma-ray source or electron linear accelerator source is available. It is used to sterilise tissue for transplantation, plasma for donation in certain circumstances, some medical devices, and pharmaceuticals.

Other potential sterilisation methods include using dry-heat, liquid chemicals, performic acid, filtration, microwave, vapourised hydrogen peroxide, ozone, formaldehyde steam, vapourised peracetic acid, and others.


In the vast majority of medical facility cases, steam sterilisation (using autoclave bags where suitable) is the preferred method of instrument sterilisation.

Whichever method is employed, sterilisation reduces the risk of both person-to-person disease and infection transmission and the transmission of environmental pathogens. This is particularly critical for any instrument or other item that enters an aseptic part of the body, including the skin and bloodstream. From hypodermic needles to scalpels, pacemakers to dental implants, and much more, the right approach to sterilisation is an essential aspect of healthcare.