Abstract: A machine accesses a first image captured prior to initiation of a procedure, where the first image depicts a set of instruments, as well as a second image captured after initiation of the procedure, where the second image depicts a proper subset of the set of instruments depicted in the first image. From the first and second images, the machine may determine that an instrument among the set of instruments depicted in the first image is not depicted among the proper subset of the set of instruments in the second image, and then cause presentation of a notification that indicates the instrument not depicted in the second image is missing. Alternatively, or additionally, the machine may determine whether an instrument among the set of instruments was used in the procedure, and then cause presentation of a notification that indicates whether the instrument was used in the procedure.