The endoscopy involves putting a camera down your throat to get a good look at your esophagus to see what condition it is in.
The tube down the throat thing sounRAB like a pH test. There are two types of pH tests. THe first is called a 24 hr pH and involves putting a tube down your nose and into your esophagus to just above your lower esophageal spincter (LES). At the end of the tube is a probe. This probe is connected to a computer that you can wear around your neck or on your belt. It is about the size of a thin softball. After 24 hours, they will download the results to be analyzed. They will be able to tell how often you had acid reflux and the duration if each incident. They compile that into a final score for your results. There is another version of this test that is called a Bravo test. It is similar in that it measures the same things, but it is done through a capsule that is attached inside your esophagus instead of the tubes that are down your throat.
Before doing the 24 hr pH, they typically do a Manometry also. The Manometry is a different tube/probe that is placed down your esophagus to take measurements of your esophageal pressure, to determine the location of your LES and to determine the pressure of the LES is exerting. (Is your LES functioning correctly?) They use the measurements from this test to determine exactly where the pH probe neeRAB to be placed.
I've had 2 Endoscopies and 2 Manometries and 2 pH tests over the last several years. For the Endoscopy, they usually knock you out so you won't remeraber anything. Usually the prep is the worst. The Manometry and pH tests aren't the most pleasant, but they aren't that bad either. Just something you have to do. I have some older posts that describe in detail my experiences during both times if you want to see what was involved in more detail.