Abstract: A dual mode handheld ultrasonic device is provided for guiding a venous access catheter into a patient's peripheral vein. It provides B-mode imaging with a predetermined aperture and operating frequency which locates and displays a gray scale cross-sectional image of the target blood vessel. A single doppler beam in a separate mode detects the same blood vessel and creates a single scanline image superimposed to such B-mode cross-sectional image. Simultaneously, the intensity of the positive doppler shift detected by the single doppler beam as it hits the target blood vessel activates a plurality of light emitting diode (LED) indicator lights with varying voltage requirements mounted in the scanhead. Activated LED indicator lights forms an arrow pointing inferiorly perpendicular to the target vessel which guides a physician or a paramedical professional to the precise catheter insertion spot on a patient's extremity while simultaneously viewing the target blood vessel's cross-section on the display screen.