Transsphincteric pH Profile at the Gastroesophageal Junction

Background & Aims: Esophageal acid exposure conventionally is measured 5 cm above the lower esophageal sphincter (LES). The aim of this study was to compare pH profiles at sites within the LES, the distal esophagus, and the proximal stomach. Methods: Ten normal subjects underwent esophageal manometry followed by 24-hour esophagogastric pH monitoring using an 8-channel pH probe recording at 5 and 1.5 cm above and at 0, 1.5, 3.0, 4.5, 6.0, and 9.5 cm below the proximal LES border. During pH recording, a 4-hour gastric emptying test with an egg sandwich meal was performed. Results: The LES was 3.2 ± 0.4 cm in length. There was a progressive increase in acid exposure from the esophageal to the gastric pH sensors. pH was less than 4 for 3.4% ± 1.6%, 12.7% ± 8.5%, 26.5% ± 10.2%, 48.1% ± 11.3%, 66.5% ± 9.9%, 80.8% ± 5.6%, 89.2% ± 3.0%, and 96.7% ± 1.1% of the total time for pH probes at 5 and 1.5 cm above and 0, 1.5, 3, 4.5, 6.0, and 9.5 cm below the proximal LES border, respectively. Percentage acid exposures correlated significantly with the position of the probe (r = −0.95; P < .01). Intrasphincteric acidity increased postprandially. Gastric emptying was correlated inversely with the intragastric hydrogen ion concentration (r = −0.82). Conclusions: The percentage of recording time that pH was less than 4 was significantly higher in the intrasphincteric area and 1.5 cm above the proximal LES compared with the traditional site 5 cm above the proximal manometric LES border. High acid exposure in the intrasphincteric region might explain the susceptibility of the distal esophagus to erosions, strictures, and Barrett's esophagus.