Portable surgical implement detector

Abstract

Surgical implements used during an operating procedure are detected in human or animal tissue. Markers attached to the surgical implements change their impedance at a preselected frequency in the presence of an electromagnetic field. Each of the markers is thereby provided with signal-identifying characteristics. The signal-identifying characteristics are detected by a freely movable, portable detection unit from a first location proximate the patient in an accurate, reliable manner. Potential cross-interference with operating room electronic instrumentation is minimized by shielding. System cost and space requirements are substantially lowered. An accidentally retained surgical implement is discovered in a timely manner, prior to completion of surgery and before the patient has been removed from the operating room. The portable detection unit is adapted to be transported to a second location from which the potential cross-interference between the electrical or magnetic fields generated during operation of the detector and the electronics deployed during the surgery is minimized. The patient is interrogated after closure of the wound by being subjected to an interrogating field generated by the surgical implement detector at the second location. Visible and/or audible signals from the detector signify accidental retention of a surgical implement before the patient awakes.