Abstract: An ultrasound system determines the presence of a foreign object in a container of fluid by measuring echo signals from the outer surface of the container and the inner surface of the container. The amplitude of the echo signals are compared to determine the presence of an object in the container. The system also determines viscosity of the contained fluid by measuring a through-transmission time through the container and the fluid, measuring an outer echo transmission time of an outer echo signal from the outer surface of the container and an inner echo transmission time of an inner echo signal from the inner surface of the container, and determining a time difference between the outer echo transmission time and the inner surface transmission time.