Medical procedure related objects (e.g., instruments, supplies) tagged with transponders may be accounted for in a medical procedure environment via a medical object accounting system using a number of antennas, and optional readers. A first set of antennas may be configured to interrogate sterile fields and/or non-sterile fields which do not encompass a body of a patient to account for the objects proximate a start and an end of a medical procedure. Sterile fields may encompass working surfaces of tables and stands, typically used by nurses. Readers (e.g., symbol, RFID) may be employed. A database may be maintained with information including a current status of each instrument or supply, for instance as checked in or checked out. On notification of a discrepancy, a handheld antenna and/or second set of antennas may interrogate a volume encompassing a body of a patient for retained instruments or supplies. The system may be automatically configured (e.g., loading appropriate software) on communicative coupling of a device (e.g., antenna, reader, peripheral device).