A flexible disposable ultrasound transducer sheath for medical diagnostic instruments comprises a core having a central opening aligned to a core axis and contoured and dimensioned in cross section in correspondence with the cross section of a standard instrument shaft where the transducer is to be removably applied. A piezoelectric layer of flexible polyvinylidene fluoride is formed over the core and a first electrically conductive gold layer electrode is sandwiched between the piezoelectric layer and the outer core surface. A second conductive layer is formed over the piezoelectric layer and includes a plurality of conductive gold strip electrodes aligned with the axis of the core, the strips being separated one from the other circumferentially. The transducer, when driven with electrical pulses, is an ultrasound emitter. As a receiver, the transducer converts returning echoes into electrical signals. Alternative embodiments include inflatable balloons over the transducer or as an element of the transducer.