The role of 3 hour distal oesophageal pH monitoring in gastro-oesophageal reflux.

It has been suggested in the literature that an eight hour period of distal oesophageal monitoring is adequate for the diagnosis of reflux in symptomatic patients. The aim of this study was to investigate whether 3 hour intra-oesophageal pH-metry could be substituted for the eight hour test period without loss of sensitivity in the diagnosis of GOR. Twenty patients were tested, 10 of whom had classical De Meester symptoms of GOR and 10 asymptomatic patients served as controls. All were commenced on 3 hour ambulant pH monitoring of the distal oesophagus. This was followed by a separate period of 8 hour testing. Each test had a 50% supine time period. The following variables were determined: (i) number of reflux episodes (ii) number longer than 5 minutes (iii) longest episode of reflux, (iv) percent of time that pH was below 4. Results are analysed using the 'Esophogram' computer program. 8 hour monitoring resulted in a positive diagnosis of GOR in 10 of 10 patients, giving an overall sensitivity of 100%. 3 hour testing was positive in 8 patients (sensitivity of 80%). The best correlations were obtained when comparing total reflux episodes, and the percent of total time pH less than 4, but overall the tests correlate poorly for individual variables. None of the controls had positive 3 or 8 hour testing. We conclude therefore, that 3 hour pH metry may be a useful screening test to confirm symptomatic reflux, and can be performed within a single clinic visit. If negative, arrangements must be made for more prolonged monitoring.