Loop electrodes for electrocautery probes for use with a resectoscope

Abstract

An electrocautery probe includes a distal loop electrode mounted between a pair of arms which are joined at their proximal ends to an electrode lead, and a mounting sleeve for slideably coupling the probe to the guide tube of a resectoscope. The loop electrode is formed with a relatively broad lower surface defining a sharp distal edge and a sharp proximal edge. The electrode may have a triangular cross section or a cross section which is defined by an upper convex surface and a lower flat surface. A presently preferred embodiment of the electrode has a triangular cross section with a lower base surface approximately 0.039-0.043 inches wide, a distal upper surface extending approximately 0.018-0.022 inches from the base, and a proximal upper surface which extends approximately 0.063-0.067 inches from the distal upper surface to the lower base surface. The electrode thereby defines a sharp distal edge having an angle of approximately 95.degree., and a sharp proximal edge having an angle of approximately 30.degree.. The electrode is preferably made of chromium cobalt or carbonless stainless steel. Tests have demonstrated that the electrode according to the invention is approximately 90% more effective in coagulation than the known loop electrodes. It is believed that the sharp distal and proximal edges aid in cutting and focus cautery current to this effect while the relatively broad base serves to enhance coagulation.