Maybe. An ultrasound may be able to see a large hiatal hernia, but it's not a reliable test for that diagnosis. Ultrasound can see most organs in the abdomen, and help determine blood flow to some organs. Upper GI contrast study is better for hiatal hernia. Hope this helps!
Not really. On rare occasions you could but ultrasound would not be the modality of choice. A barium swallow study called an upper GI would be best.
No. An ultrasound sees more solid organs & does not see through air filled structures like the intestines. An utrasound will see the liver, gallbladder, kidneys, part od pancreas, major blood vessels, etc.