FIG. 1 is a front view of a medical diagnostic device of the present invention; FIG. 2 is a front, side perspective view thereof; FIG. 3 is another front, side perspective view thereof; FIG. 4 is a rear view thereof; FIG. 5 is a bottom view thereof; FIG. 6 is a top view thereof with a cover removed; FIG. 7 is a top, front perspective view thereof; FIG. 8 is a front view thereof; FIG. 9 is a side view thereof; and, FIG. 10 is a top, side perspective view thereof.