An ultrasound system (100) includes an ultrasound transducer, a processing circuit (300), and a display. The ultrasound transducer is configured to detect ultrasound information from a patient (610) and output the ultrasound information as an ultrasound data sample (612), the ultrasound information representing blood flow of the patient. The processing circuit (300) is configure to determine a first characteristic of a first plurality of the ultrasound data samples (614) detected prior to a current ultrasound data sample, the first characteristic representing periodic features of the blood flow, determine a second characteristic of the current ultrasound data sample (616), compare the first characteristic to the second characteristic (618), modify the current ultrasound data sample based on the comparison (620), and output spectrum information (622) of the current ultrasound data sample modified based on the comparison of the first characteristic and the second characteristic. The display is configured to display the spectrum information (624).
