Why hiatal hernia sometimes goes undetected in endoscopy? what all would be the best(no escape) tests to detect a hiatal hernia?

Here is why...: Just remember the following two facts: no test has yielded 100% of accuracy; every life event or disease always displays itself as a pattern of full spectrum from its very early hardly detectable state to its late obvious condition. So, when the condition is mild, the picture could be elusive ; very difficult to find it; when severe, easy to find it. For now, just treat what it can be, and repeat.

Sliding hiatal herni: Many hhs are the sliding type in which the gastroesophageal junction migrates. During endoscopy, the gas from the scope pushes the hernia back into the abdomen making the hernia undetectable. Most common symptoms of hhs are reflux. Tests for reflux include barium studies, ph probe testing and endoscopy. No single test can detect hiatal hernias in all cases.