Reflux or backflow of the acidic and nonacidic contents of the stomach into the esophagus can occur due to dysfunctional lower esophageal sphincter (LES) muscles. This can lead to a condition called gastroesophageal reflux disease (GERD) which slowly damages the esophagus and can lead to esophageal cancer. An impedance study is performed to measure the extent of reflux due to the nonacidic contents. It is a 24-hour study usually combined with a pH study.
Prior to the test, you are asked to gradually withdraw from all acid-regulating medication and fast for a period of 4-6 hours.
During this test, your doctor places a thin probe through your nose and down your esophagus. The tip of the tube is precisely positioned with the help of X-ray imaging and has sensors that can detect acidity levels as well as changes in pressure due to reflux. The other end of the tube is taped to the side of your face and connected to a portable recording device fixed to your belt or shoulder. The device stays in for a period of 24 hours and has buttons to indicate activities such as eating and sleeping. The test measures the amount of liquid or gas content refluxing into the esophagus and determines the presence and severity of gastroesophageal reflux disease.