Ultrasonogram of the omasum. Ultrasonogram of the omasum and liver of a 27-day-old Swiss Braunvieh calf with ruminal drinking syndrome. The 5.0-MHz linear transducer was held on the right side parallel to the ribs in the 8th intercostal space. The omasum is seen medial to the liver as a crescent-shaped echo with the convex side toward the transducer. 1 Abdominal wall, 2 Liver, 3 Portal vein, 4 Omasum, Ds Dorsal, Vt Ventral.