What is Sterilization?

Hospitals are legally expected to provide their patients with the utmost care, which includes the proper sterilization of medical tools and equipment to prevent the risk of infection. However, sterilization is no easy task; only individuals who have received sterile processing technician online training from reputable institutions can thoroughly eliminate microbes from medical instruments.

If you are interested in receiving SPT training to become a certified sterile processing technician, you can take some helpful knowledge on sterilization in our infographic below:

Cleaning vs. Disinfecting vs. Sterilizing

It is common for people to assume that cleaning, disinfecting, and sterilizing all mean the same thing and are thus interchangeable. But, when undertaking sterile processing technician training, you’ll learn these three terms are different methods.


The process of cleaning involves removing visible dust, dirt, and soil from surfaces, typically with a wipe and soap. Cleaning does not kill or thoroughly remove bacteria and other microbes.

Cleaning is essential before disinfection since leftover soil may inactivate the disinfectant or sterilant. Cleaning is typically done after direct contact with a patient or using non-critical tools such as stethoscopes.


The process of disinfection involves killing or inactivating bacteria and viruses using products designed specifically for certain microbes. While this method is reliable in eliminating known germs and viruses, it might be inefficient against emerging pathogens.

The effectiveness of disinfection depends on several factors, such as the efficacy of prior cleaning, type of microbial contamination, compatibility of instruments with chemicals, and presence of biofilms.


The process of sterilization involves destroying or eliminating all microbial life. Professionals such as sterile processing technicians for surgeries and laboratories often carry out this procedure.

Sterilization is performed after precleaning and decontamination. Critical items, including all surgical tools, catheters, and ultrasound probes, must undergo sterilization in the sterile processing department.

The Three Main Categories of Medical Devices

While all medical equipment requires thorough sterilization before usage, the level of decontamination or sterilization may depend on the category to which they belong. According to Dr. Earl Spaulding, these are the three main categories:

Non-critical Items

These refer to those that only come in contact with intact skin. Since non-critical items do not penetrate the sterile body cavities or mucus membranes, they require a minimum of a low-level disinfection process.


  • Stethoscopes

  • Blood glucose meters

Semicritical Items

Semicritical items include those that come in contact with the mucus membranes but not the sterile body cavities. These items require a high-level disinfection process.


  • Endoscopes

  • Ear/Nose/Throat instruments

Critical Items

Critical items come in contact with the sterile body cavities, requiring sterilization to eliminate microorganisms thoroughly.


  • Syringes

  • Implants

The Process of Precleaning and Decontamination

Surgical instruments undergo a tedious process before they are declared safe to reuse. An average person cannot perform the sterilization process due to great attention to detail and careful inspection. Because microbial life is difficult to eliminate, sterile processing technicians, follow a series of standard procedures they are vigorously trained to master:

  • Before anything else, hospitals first sort, inspect, and disassemble soiled instruments.

  • The soiled instruments undergo precleaning at the point of use. The precleaning may be done through irrigation using distilled water or spraying with gel or a transport foam, often an enzymatic cleaner.

  • The instruments are then immersed in a detergent solution and brushed manually.

  • Afterwards, the instruments are rinsed with clean, treated water.

  • An ultrasonic cleaner may remove residual patient soil if the instrument can tolerate sonication.

  • Any eligible instruments must undergo additional mechanical disinfection using an automated washer/disinfector.

  • Once the instruments are thoroughly cleaned after the precleaning and disinfection procedures, they can be sterilized.

How the Sterilization Process is Carried Out

After decontamination, the instruments are sent to the Sterile Processing Department (SPD) for preparation and packing. The items are then carefully inspected and assembled in a set or peel-packed.

During sterilization, the instruments are subject to conditions and chemicals that bacteria, viruses, and other microorganisms cannot survive. There are many methods of sterilization, including:


Autoclave sterilization is also called steam sterilization.

Steam is the most widely used method for sterilization in the SPD. This method uses a combination of heat, moisture, and pressure to eliminate any microbial life. There are two common autoclaving or steam sterilization processes used based on how air is vented out the threshold and how the steam is vented in:

  • Gravity Displacement – this method lets steam in from the top of the autoclave machine and pushes the air out of the bottom. Gravity displacement is the simplest and oldest form of steam sterilization and takes longer than other alternatives. Gravity displacement is ideal for simple tools but ill-suited for complex instruments and other items that the vacuum may damage.

  • Dynamic Air Removal involves an autoclave machine alternating steam and vacuum pulses or steam pulses and venting to ambient pressure to remove air from the instruments and chamber, allowing steam to penetrate the load. The latter is also called Steam Flush Pressure Pulse (SFPP). Dynamic air removal is the preferred method as it is more efficient and quicker.

Low-Temperature Technologies

Not all instruments are suitable for autoclaves since heat and moisture may damage them. As an alternative, the SPD may instead use the other alternatives under low-temperature technologies:

  • Ethylene Oxide – this low-temperature method used to be dominant among other choices, but because it takes longer (1 – 4.5 hrs.), it has since been replaced by vapor hydrogen peroxide. This method has five stages: preconditioning and humidification, gas introduction, exposure, evacuation, and air-washes. Aeration may add 12 – 36 more hours.

  • Vapor Hydrogen Peroxide is the most dominant method to sterilize heat-sensitive equipment and devices. This method involves H2O2 vapor filling the chamber and contacting exposed devices. After sterilization, the vapor is removed and converted to water and oxygen.

  • Ozone Sterilization – ozone sterilization is the latest sterilization method. Ozone can destroy any microbe thanks to the additional oxygen atom attached to its molecules while not leaving any toxic emissions and chemical residues.

  • Liquid Chemical – is safe and effective for heat-sensitive, semicritical devices.

The Value of Sterile Processing Technicians

The process of sterilization is labor-extensive and does not leave room for mistakes. Despite working in the background, sterile processing technicians are critical in ensuring patient protection by sterilizing hundreds of trays of medical instruments daily.

If you are considering a career in allied health, enroll in courses to become a sterile processing technician. You do not need to possess a degree in tertiary education to join an SPT program, and you will only be spending at least six months until completion. Once you pass the certification program, you are on your way to becoming a valuable member of the healthcare industry.

Choosing a reliable institution for SPTs is a factor in determining how well you’ll perform as a future Sterile processing technician. Begin your journey today by enrolling in Martinson College’s quality accelerated adult and online programs!