A pH/Impedance study is a test designed to see if your child has reflux [the contents of the stomach coming back out the stomach into the oesophagus (food pipe)]. A pH/Impedance probe is a long, fine, flexible tube which is inserted through the nose and down the back of the throat. One end of the probe is taped to the side of the face and the other end sits at the bottom of the oesophagus. The probe is usually placed under sedation or general anaesthetic.

A small box is attached to the tube. This records the results of the test which usually last 24 hours.

A diary is kept by the parents of any food, sleep or symptoms that occur while the test is being carried out.