A system includes a number of transducers configured to transmit ultrasound signals directed to a target blood vessel and receive echo information associated with the transmitted ultrasound signals. The system also includes a processing device configured to process the echo information, generate ultrasound images of the blood vessel at a number of locations and generate an estimated diameter of the blood vessel at the locations. The processing device is also configured to output image information associated with the blood vessel and output a maximum estimated diameter of the blood vessel or the estimated diameters at the number of locations based on the image information.