Determination of pH turning point with pH mapping of the gastroesophageal junction: an alternative technique to orientate esophageal pH monitoring.

Manometric location of the lower esophageal sphincter (LES) has been mandatory before esophageal pH monitoring, despite costs and discomfort related with esophageal manometry. The aims of the study were: (i) to map the pH of the gastroesophageal junction (GEJ) to determine a pH turning point (PTP) and its relation with LES; and (ii) to test the feasibility of this technique to orientate esophageal pH monitoring. We studied 310 adult patients who underwent esophageal manometry and pH monitoring off acid-suppressive therapy. GEJ pH mapping was carried out by step-pulling the pH sensor from 5 cm below to 5 cm above LES, and a PTP was determined when pH changed from below to above 4, in centimeters from the nostril. Thirty-six patients referred only for pH monitoring were studied with pH sensor placed at 5 cm above the PTP. Out of 310 patients, a PTP was found in 293 (94.5%): inside LES in 86.3%, into the stomach in 8.2% and in the esophageal body in 5.5% of patients. The median distance between PTP and place where pH sensor monitored reflux was 8 cm. Among 36 patients who performed pH monitoring without LES manometry, there was no gastric monitoring during reflux testing. In adult patients investigated off acid suppressive therapy, GEJ pH mapping with reflux monitoring 5 cm above the PTP can be an alternative technique to perform esophageal pH monitoring when LES manometry is not available. Additional studies are needed before the widespread use of GEJ pH mapping in the clinical practice.