Diagnostic tests can help in understanding the extent of acidity and help in deciding the course of the treatment. Some diagnostic tests for acidity include: Barium – A solution containing barium is swallowed and the movement is tracked using an X-ray. pH Monitoring – A device is inserted into the patient’s esophagus and left there for 1 or 2 days. The device measures the amount of acid in the esophagus. Esophageal Manometry is a device to check the function of the esophagus and the lower esophageal sphincter. Endoscopy – A long flexible tube that has a light and a camera is inserted down the throat. The camera shows the esophagus and the stomach, their contents and the mucus lining. Biopsy – A small sample of the stomach tissue may be taken for analysis and biopsy. The sample is usually taken during endoscopy.