The ideal dissecting instrument is safe, selective, able to cut and coagulate, relatively easy to learn, and affordable. The search for such an instrument led us to the ultrasonic dissector. Harmonic® shears, which use 55,000 Hz of vibration to cut and coagulate, elicit minimal lateral tissue damage, charring and desiccation, and smoke for good visibility of the surgical site, as well as allowing no electricity to pass to the patient. It is widely used in general, gynecologic, urological, and minimally invasive surgeries. Harmonic shears® are also widely used in thyroid surgery.

Ultrasound has had a strong impact on the practice of modern medicine, and depending on ultrasound frequency, it can be used in different ways. At low frequency, ultrasound causes no tissue damage and is mainly used for diagnostic purposes. At high frequency, by contrast, ultrasound can be used to dissect, cut, and coagulate. Several high-frequency ultrasonic devices are available.

Extracorporeal shock wave lithotripsy, which has been used to treat cholelithiasis and nephrolithiasis, is another beneficial adaptation of acoustic wave technology. In brief, the patient is placed in a water bath and a high-energy acoustic shock wave is generated by piezoelectric or electromagnetic technology. The water-tissue interface allows the wave to pass through normal tissue without injuring it. The energy of the shock wave is focused on the offending stone by ultrasound and causes disruption and fragmentation of the calculus, which is then passed via the ureter.

Harmonic® shears use ultrasound to dissect tissue with minimal collateral tissue damage. The high-frequency vibration of molecules within tissues generates stress and friction, which in turn generates heat and protein denaturation. Because of its unique ability to dissect and coagulate tissue simultaneously, this device has gained popularity among surgeons.

The Cavitron® ultrasonic surgical aspirator is an ultrasonic instrument that uses low-frequency ultrasound to fragment and aspirate tissue with low fiber (i.e., collagen) but high water content. It is basically an ultrasonic probe combined with an aspirator. The Cavitron® ultrasonic surgical aspirator has a wide variety of applications. Because it can fragment and aspirate tissues of low fiber and high water content, it is especially useful for liver and pancreatic procedures (e.g., for resecting lesions in noncirrhotic livers and for removing small pancreatic tumors in the absence of fibrosis). It has also been used for partial nephrectomy, salvage splenectomy, head and neck procedures, and gynecologic tumors. This device also elicits minimal blood loss and tissue injury and produces good visibility of the surgical site.