context: Three out of every 10 people experience heartburn on occasion, so it can be somewhat arbitrary to decide when heartburn should be called acid reflux disease. Also known as gastroesophageal reflux disease ( GERD), acid reflux disease is a chronic irritation of the lining of a person's esophagus by stomach acid. Usually, it's just annoying. GERD can, however, have serious consequences, including esophagitis and Barrett's esophagus. Barrett's esophagus is a condition that increases the likelihood of esophageal cancer. People with acid reflux disease often have some or all of the following symptoms: Pain when or difficulty swallowing Bad breath and/or bad taste in the mouth Burping Chest pain Heartburn Hoarseness Regurgitation Sore throat Cough Asthma If you experience classic symptoms of acid reflux disease -- chronic heartburn and regurgitation -- without any troublesome complications, it may be relatively easy for your doctor to make an acid reflux diagnosis. A few people have GERD that doesn't respond to treatment. Or they may have other concerning symptoms, such as weight loss, difficulty swallowing, anemia, or black stools. If you're one of them, you may need any of the following tests. Your doctor may decide to use a special X-ray procedure -- the barium swallow radiograph -- to rule out any structural problems in your esophagus. In this painless acid reflux test, you will be asked to swallow a solution of barium. The barium enables doctors to take X-rays of your esophagus. Barium swallow isn't a surefire method of diagnosing GERD. Only one out of every three people with GERD has esophageal changes that are visible on X-rays. During an endoscopy, the doctor inserts a small tube with a camera on the end through the mouth into the esophagus. This enables the doctor to see the lining of the esophagus and stomach. Before inserting the tube, your gastroenterologist may administer a mild sedative to help you relax. The doctor may also spray your throat with an analgesic spray to make the procedure more comfortable for you. This acid reflux test typically lasts about 20 minutes. It is not painful and will not interfere with your ability to breathe. While this test may detect some complications of GERD, including esophagitis and Barrett's esophagus, only about half the people with acid reflux disease have visible changes to the lining of their esophagus. Depending on what the EGD shows, your doctor may decide to perform a biopsy during the procedure. If this is the case, your gastroenterologist will pass a tiny surgical instrument through the scope to remove a small piece of the lining in the esophagus. The tissue sample will then be sent to a pathology lab for analysis. There it will be assessed to see if there is an underlying disease such as esophageal cancer. Your doctor may perform an esophageal manometry to help diagnose acid reflux. This is a test to assess your esophageal function. It also checks to see if the esophageal sphincter -- a valve between the stomach and esophagus -- is working as well as it should. After applying a numbing agent to the inside of your nose, the doctor will ask you to remain seated. Then a narrow, flexible tube will be passed through your nose, through your esophagus, and into your stomach. When the tube is in the correct position, the doctor will have you lay on your left side. When you do, sensors on the tube will measure the pressure being exerted at various locations inside your esophagus and stomach. To assess your esophageal functioning even further, you may be asked to take a few sips of water. The sensors on the tube will record the muscle contractions in your esophagus as the water passes down into your stomach. The test typically takes 20 to 30 minutes. To obtain an even more detailed picture of how your esophagus functions, the gastroenterologist may recommend esophageal impedance monitoring. If so, this can be done in conjunction with manometry. This test uses a manometry tube with electrodes placed at various points along its length. It measures the rate at which liquids and gases pass through your esophagus. When these results are compared with your manometry findings, your doctor will be able to assess how effectively your esophageal contractions are moving substances through your esophagus into your stomach. This test uses a p H monitor to record the acidity in your esophagus over a 24-hour period. In one version of this test, a small tube with a p H sensor on the end is passed through your nose into your lower esophagus. The tube is left in place for 24 hours with the portion exiting your nose affixed to the side of your face. It will be connected to a small recording device that you can wear or carry. During the course of this acid reflux test, you will record in a diary when you are eating or drinking. You will also push a specific button on the recording device to indicate when you are experiencing acid reflux symptoms. This detailed information will allow the doctor to analyze and interpret your test results. A newer, wireless version of this test is now being used. In this version a small p H sensor is affixed to your lower esophagus using suction. The small capsule is able to communicate wirelessly with a recording device outside your body for 48 hours. The capsule ultimately falls off and passes through the remainder of the digestive tract. Many patients have found the wireless p H monitoring exam to be far more pleasant than the traditional version. Both techniques yield similarly information.