Testing sterilization quality relies on biological indicators. These indicators carry spores of highly resistant microorganisms and are placed inside representative loads or in challenging locations. After the cycle, they’re incubated to see if any growth occurs. If there’s growth, it means the sterilization process didn’t kill even the toughest spores, signaling a failure. If there’s no growth, you have direct evidence that the sterilization was effective, because it demonstrates microbial kill. That direct evidence is why biological indicators are considered the most reliable way to verify sterilization. Chemical indicators show that the right conditions (like temperature and exposure) were reached, but they don’t prove sterility. Process indicators confirm the cycle ran, not the outcome for the load. Sterilization logs document parameters and trends but do not test whether the load was truly sterile.