Information on Gastrointestinal Investigations
Understanding Oesophageal pH/Impedance Monitoring
What is an oesophageal impedance-pH study?
A 24hour oesophageal pH/Impedance study is an outpatient test that measures the amount of reflux of stomach contents into the oesophagus, and relates this to your symptoms. Sensors placed in the oesophagus measure acid (pH) or movement of fluid and gas (impedance) which correspond to acid and non-acid reflux respectively. Sometimes only acid (pH) monitoring is needed, sometimes both, but the procedure only involves one sensor (catheter) in the oesophagus for the 24hours. You will wear a data recorder during the test and record any symptoms you experience during the study.
Why is an oesophageal pH/Impedance study performed?
Oesophageal pH/Impedance studies measure the amount of reflux that occurs in a typical 24 hour period. By analyzing episodes of reflux with associated symptoms this tests helps your doctor determine if your symptoms are due to gastro-oesophageal reflux disease. The test may be performed as part of the pre-operative evaluation for gastro-oesophageal reflux surgery.
What preparation is required?
An empty stomach allows for the best and safest examination. Therefore, you should have nothing to eat or drink for six hours before your procedure. If you have any questions about dietary recommendations, please contact the number on your appointment letter.
Can I take my current medications?
Some medications need to be stopped before the test. Tell your doctor about your medications and your allergies. You will be informed in your appointment letter which if any medications need to be withheld, and for how long. If you have any questions about your medication please contact the number on your appointment letter.
What happens during an oesophageal pH/Impedance study?
24hour oesophageal pH/Impedance is a generally well-tolerated outpatient procedure. You should wear comfortable loose-fitting clothing. In most cases oesophageal manometry (see separate information) is performed immediately beforehand, to ensure the reflux sensor is placed accurately. You will not receive sedation during the procedure. A local anaesthetic is first sprayed into your nostril, then a manometry catheter is inserted gently and advanced slowly into the oesophagus. Measurements of the pressures in your oesophagus are made over approximately 15 minutes, and the catheter is removed. Then the pH/Impedance catheter (which resembles a thin plastic-coated wire), is inserted in the same way. The catheter will be secured to your nostril with tapeand connected to a data recorder that you will carry on a strap and wear overnight. The initial procedure itself usually takes approximately 30 minutes, although you should plan to be at the unit for approximately one hour. This will include the registration, preparation and procedure.
What happens after oesophageal pH/Impedance study?
You will be able to drive yourself home after placement of the oesophageal pH/Impedance probe. Oesophageal pH and impedance data will be collected and stored on the data recorder. The following day you will return to the unit to have the catheter removed and return the data recorder. The information will be analysed and reviewed by a doctor. It may take up to two weeks for your doctor to contact you or see you with the results.
What are possible complications of oesophageal pH/Impedance study?
Oesophageal pH/Impedance study is very safe when performed by trained and experienced staff. Complications are rare. Patients may have nasal irritation during or after the procedure.