I have had this test done 3 times. The unpleasant part for me (and everyone according to the tech) is getting past the gag reflex as the tube hits the throat. Once that is done, and you relax, it is a breeze. The tech will measure the pressure at the Lower esophagal sphincter and then withdraw the tube in 5 cm increments and have you swallow a bit of water he gives you. It measures abnormal esophagal motility disorders (achalasia, Barrets, nutcracker esophagus, and diffuse esophagal spasm. It takes about 30 minutes. Both of the techs I had do my tests says that about 1 in 10 people can not get the tube down due to gagging, and therefore not do the test (I hope that isn't you. Diffuse esophagal spasm and a hypertensive LES can give strong non-cardiac chest pain. If the pain comes from the esophagus, it is fairly easily treated once the source is known.