Ultrasonic sensing systems are incorporated into surgical instruments to monitor operational fields defined by distal ends of the instruments. The instruments include proximal ends for their activation typically including one or a pair of handles which a surgeon grasps and operates, for example by squeezing the handles together or by pivotally moving a trigger portion of the handle relative to a fixed portion of the handle. Circuitry for performing ultrasonic sensing preferably is enclosed in housings defined within the handles of the proximal ends of the instruments. Wiring, preferably running through the instruments, connects the circuitry to transducers formed in or mounted on the distal ends of the surgical instruments. The transducers direct ultrasonic energy to the operational fields defined by the distal ends of the instruments and receive ultrasonic energy reflected from the operational fields. The direction for transmission and receipt of ultrasonic energy is determined by acoustic lenses, angularly oriented transducer mounts or a combination of the two. Signals representative of the tissue or contents of the operational fields of surgical instruments drive audible signal generators or preferably tactile transducers to inform the surgeon of the contents. Tactile transducers are mounted for access by the surgeon, preferably on the handles of the surgical instruments.