Reflux: how do pH monitoring, impedance testing and manometry differ?

For gastro-oesophageal reflux that has already been assessed, the gastroenterologist may prescribe additional measurements, particularly for atypical symptoms or before surgery. These tests are not required for every reflux problem: confirm which is planned and the specific question it addresses.

pH monitoring records changes in acidity in the oesophagus. Impedance testing records liquid moving back up from the stomach and can therefore detect weakly acidic reflux. These measurements complement each other but are different.

In the catheter system described by Ameli, an electrode is placed in the oesophagus through the nose after local anaesthesia and connected to a recorder. Recording lasts eighteen to twenty-four hours; some wireless systems allow a longer period.

During this recording, the patient marks symptoms as they occur by pressing a button on the recorder. Ask to be shown how on the planned device. This locates symptoms within the recording; it does not mean you should interpret measurements yourself.

Manometry measures pressure in the oesophagus and studies contractions and relaxation, often before reflux surgery. It also differs from gastroscopy, which observes the walls with a camera and may allow samples to be taken.

Before the appointment, check the exact test name and ask for its preparation instructions. Clarify how to mark symptoms, return the equipment and receive an explanation of the result. Do not assume instructions for another examination automatically apply.