Certified Surgical Technologist (CST) Practice Exam

What is the minimum time for sterilization using ethylene oxide?

1. 1 hour

2. 3 hours

3. 12 hours

4. 24 hours

The correct answer is: 12 hours

Ethylene oxide sterilization is a widely used method for sterilizing medical and surgical equipment, particularly for items that cannot withstand high temperatures or steam. The minimum time required for effective sterilization with ethylene oxide is critical for ensuring that microorganisms are adequately eliminated. The sterilization process not only involves exposure time but also requires proper conditions, including temperature, humidity, and gas concentration. Although items may be exposed to ethylene oxide for as little as 1 hour, three hours, or even 12 hours, it is the combination of these parameters that determines effectiveness. Typically, for ethylene oxide sterilization to achieve a high level of assurance against viable microorganisms, the minimum practice duration is set at around 12 hours. This time frame allows the gas to penetrate the items properly and ensures adequate exposure for sterilization. While sterilization processes may have shorter times in some circumstances, 12 hours is widely regarded as the minimum effective time for achieving sterility in most standard applications. With this understanding, it becomes clear why the answer is grounded in the context of safety and efficacy in sterilization protocols.