About Ultrasound Ultrasound FAQ Preparing for Ultrasound Ultrasound Preparations Gallbladder, Liver, Abdominal and Aorta U/S - No food 8 hours prior to the exam. Water only if you need to drink liquids. Pelvis and Transvaginal and Obstetrics U/S - 1 to 2 hours before your exam, drink at least 2 large glasses of water (32 ounces) and maintain a full bladder. Kidney and Renal Doppler U/S - No food 8 hours prior to the exam. Drink at least 2 large glasses of water (32 ounces) and maintain a full bladder. Thyroid, Breast, Echocardiogram, Vascular and Carotids U/S - No preparation is required. Note: Take all medications with water only. © 2004 University MRI