Abstract: An ultrasonic probe for flow rate measurement is disclosed having a plurality of transducers mounted on a flexible cable configured to be inserted in a body cavity to obtain cardiac or other biometric telemetry. The flexible cable is provided with a disposable body which covers and microbially isolates the flexible cable and transducers. The disposable body is flexible and permits rotation of the flexible cable within it. Removal and replacement of the disposable body allows the probe to be used again without sterilization of the probe itself. A sensor window may be provided in the disposable body to allow transmission of ultrasonic signals, said window being provided with an anechoic surface treatment to reduce reception spurious ultrasonic echoes due to the material of the sensor window.