High intensity ultrasound (HIU) is used to facilitate surgical procedures, such as a laparoscopic partial nephrectomy, with minimal bleeding. An apparatus is configured to emit HIU from one or more transducers that are attached to a minimally invasive surgical instrument. Such a tool preferably can provide sufficient clamping pressure to collapse blood vessels' walls, so that they will be sealed by the application of the HIU, and by the resulting thermal ablation and tissue cauterization. Such an instrument can provide feedback to the user that the lesion is completely transmural and that blood flow to the region distal of the line of thermal ablation has ceased. Similar instruments having opposed arms can be configured for use in conventional surgical applications as well. Instruments can be implemented with transducers on only one arm, and an ultrasound reflective material disposed on the other arm.