The present invention provides a multiplex system for identifying the presence of surgical sponges, metal instruments, and other implements in a surgical wound by employing a plurality of discrete sensing systems. At least two modalities of operation are chosen from a plurality of detection modalities, which can include: 1) magnetomechanically resonant marker tags; 2) “smart markers” or RFID markers; and 3) a system designed to detect metallic objects solely based upon their metal content, without need for a separate, affixed marker. The selected modes of operation can operate sequentially or simultaneously. Consequently, the use of such a multiplex system eliminates the possibility that surgical implements, non-metallic or metallic, will be left behind within a surgical cavity.