All the images above led us to the diagnosis of the inferior vena cava interruption with the azygos vein continuation and with normal visceral situs.
Images 21, 22, 23, and 24: The following images are confusing because of the presence of a vessel (arrows) coming from the caudal region of the fetus and joining the right atrium (RA). As the color Doppler images bellow show, the vessel turned out to be an aberrant venous return from the right fetal kidney connected directly to the right atrium of the heart.