What Is the Bowie-Dick Test? Why Is It Performed Daily in Steam Sterilizers?
For sterilization to succeed in pre-vacuum steam sterilizers, steam must reach every point of the packs and instruments. The prerequisite for this is the complete removal of air from the chamber and the load. Even a small air pocket left in the chamber can prevent steam contact and leave that area non-sterile.
The Bowie-Dick test is a daily performance test that shows whether the sterilizer removes air sufficiently and whether steam penetrates the load evenly.
What Does the Bowie-Dick Test Check?
The test evaluates the effectiveness of the pre-vacuum phase and steam penetration. The indicator sheet in the centre of the test pack shows, through a colour change, whether steam has reached the centre of the pack.
The most common reasons for a failed test are:
- The vacuum system failing to remove enough air
- Air leaks at the door seal or connections
- Non-condensable gases in the steam
- Problems with steam quality
Why Is It Performed Every Day?
The Bowie-Dick test is performed before the sterilizer is put into use each day, usually as the first cycle and with an empty chamber. This confirms that the device can be used safely that day before any loads intended for patients are processed.
The performance requirements of the indicators used in the test are defined in ISO 11140-4 (indicators used with a test pack) and ISO 11140-5 (Bowie-Dick type air removal tests).
How Is the Result Evaluated?
Pass: A uniform, complete colour change is seen across the entire indicator sheet. This shows that steam has reached the centre of the pack.
Fail: A lighter area or an uneven colour change is seen in the centre of the sheet. This shows that air was not completely removed.
If the test fails, the sterilizer must not be used for patient loads; the test should be repeated and, if the result is still negative, the device should be checked by technical service. Recording all test results with dates is important for the traceability of the sterility assurance system.
The Difference Between the Bowie-Dick Test and the Helix Test
The Bowie-Dick test evaluates air removal and steam penetration for porous loads (such as textile packs). For long, narrow-lumen (hollow) instruments such as laparoscopic instruments, a Helix test (hollow load process challenge device, PCD) is used to see whether steam reaches the far end of the lumen. The two tests are not interchangeable; they can be used together depending on the type of load.
Sterilizasyon Medikal Solutions
At Sterilizasyon Medikal we offer Bowie-Dick test packs, Bowie-Dick Helix tests and Helix test systems for central sterile services departments. To learn more about our products and the right test solutions for you, get in touch with us.