In one aspect, the present disclosure pertains to ultrasonic treatment devices that comprise: (a) a flexible elongate body having a proximal end and a distal end, the flexible elongate body being configured for insertion to a target site within a patient; (b) an effector assembly disposed at the distal end of the flexible elongate body, the effector assembly comprising a piezoelectric transducer and an end effector; and (c) flexible electrical conductors in electrical communication with the piezoelectric transducer, the flexible electrical conductors extending along a length of the flexible elongate body, wherein transference of electrical energy to mechanical motion takes place via the piezoelectric transducer at the target site. Other aspects of the present disclosure pertain to systems employing such ultrasonic treatment devices and methods of treatment using such ultrasonic treatment devices.