Ambulatory 24-hour pH probe:

An Ambulatory 24-hour pH probe study measures the acid that refluxes back up from the stomach. Any medications in use for reflux are usually stopped for at least 24 hours before the test is scheduled to begin, and in some cases up to 5 days before.

A very thin tube, thinner than a feeding tube is inserted up through the nostril, and then down the throat and esophagus until it reaches just above the stomach (similar to an NG tube). It has a very small probe at the end, that will register any acids that are refluxed from the stomach.

An x-ray is taken to make sure that the probe has been positioned correctly. The other end of the thin tube is attached to a small computer (small black box) for 12 or 24 hours. During this period you are given a diary sheet to complete, on which you should record the time of each activity that takes place, basically a running history.

This means for example -
14-35hrs - vomited whole bottle - upright
14-36hrs - crying - upright
14-45hrs - sleeping - flat

The position of you or your infant is important. Upright means at an angle of 45 degrees or more, flat means at an angle less than 45 degrees. You are usually free to move around during the test. Some hospitals may allow you to go home and come back once the test is complete, to hand back the small black box and have the tube removed. Other hospitals prefer you remain resident for the full duration of the test.

When the 12 or 24hrs are over, they tally up the readings on the computer, along with the history you have written. By studying all the data from probe, against the diary sheet the consultant can then determine the severity of your reflux.

Bravo pH receiver

This is a new type of pH probe which requires no tube though the nose. It is a sensor that is attached to the lining of the esophagus, with an endoscope. Often this procedure is carried out at the same time as having an endoscopy (upper GI) performed. The pH sensor sends signals to a portable computer which collects the data about the acid exposure over the usual 24 hrs. There is no removal procedure, the sensor will slowly detach itself from the esophagus with time and is then passed though a normal stool.

Multichannel Intraluminal Impedance (MII) pH / Impedance Test

Similar to a standard pH test, but with two probes. One sits in the stomach and the other just above the stomach. The advantage of the dual sensor is that it can detect both acid and alkaline reflux travels.

The tube is inserted through the nostril (this can be placed whilst still sedated after an endoscopy), and the other end is attached to a small computer, no bigger than a Walkman.

Written by Tracey (LWR Chairman)