2.9 Measurement of the pH value of gastric juice
In rare cases neither with gastrointestinal passage nor coloscopy is it possible to reliably diagnose hiatal hernia with reflux of acidic stomach contents into the oesophagus (reflux disease). In such cases, the pH value of the stomach juice must be measured over a period of 24 hours (24-hour pH metry). This measurement is conducted via a probe that is inserted into the oesophagus during coloscopy and left there for 24 hours. In this way, the quantity of gastric juice flowing back into the oesophagus can be determined. Under normal conditions, only in isolated cases are acidity values below pH 4 measured. Any values below that reading persisting over a long period of time are deemed abnormal.