Esophageal manometry is used to study how the esophagus (swallowing tube) is working. The child is awake for this test. A small tube (catheter) is passed through the nose and into the esophagus. The child is then asked to swallow both with and without sips of water to drink. The catheter is attached to a computer that records the strength and coordination of muscle contractions in the esophagus that occur with these swallows. The catheter needs to be moved during the study to test different areas of the esophagus.