Objective: To implement, execute and evaluate a quality assurance test protocol for clinical ultrasound transducers that is software-based, user-independent, inexpensive, easily repeatable, and does not require tissue phantoms. Methods: The test protocol is based on in-air reverberation images. The software test tool generates uniformity- and reverberation profiles to monitor system sensitivities and signal uniformities that provide a sensitive analysis of transducer status. Whenever a transducer was suspected to be damaged validating tests were conducted using the Sonora FirstCall test system. A total of 21 transducers from five ultrasound scanner systems were included in the study. Tests were performed every other month for a total of 5 years. Results: Each transducer was tested on average 11.7 times. Testing a transducer required a total of 2.75 hours annually. The ultrasound quality assurance test protocol detected an average annual fail rate of 10.7%. The test protocol provides a reliable approach for monitoring transducer lens status of clinically used ultrasound transducers. Conclusion: The ultrasound quality assurance test protocol may potentially find deviations in diagnostic quality before being noticed by the clinicians. Thus, the ultrasound quality assurance test protocol holds the ability to reduce the risk of undiscovered image quality degradation hereby minimizing the danger of diagnostic errors.