The insertion of a needle or other surgical instrument into the body is guided by three dimensional ultrasonic imaging. A probe having a two dimensional array transducer is placed against the body and manipulated to acquire an image of the site of the surgical procedure inside the body. The clinician inserts the surgical instrument, trying to follow an insertion path which is in the plane of a single image produced by the ultrasound system. The clinician observes the path of insertion and insertion progress on a display of a plurality of real-time 2D ultrasound images of spatially adjacent planes of a volume including the surgical procedure site. If the insertion path of the instrument does not remain in the plane of a single image, portions of the instrument will appear in the images of multiple adjacent image planes when the instrument intersects a succession of image planes as it progresses toward the site of the surgical procedure.
