Responsive power saving is provided for ultrasound imaging, such as in portable ultrasound systems. By reducing scan line density in response to removal of a transducer from a patient, power usage may be reduced while still monitoring for return of the transducer to the patient. By disabling the display, power usage may be reduced while still monitoring for return of the transducer to the patient. All or most electronics not associated with monitoring for the return of the transducer to the patient may be disabled or not used to conserve power.