Is a fluoroscopic verification of the electrode position necessary in ambulatory intragastric pH monitoring?

To assess whether a fluoroscopic verification of the electrode position is necessary before and whether electrode displacement occurs during intragastric pH measurements, a crossover study was performed in 20 healthy male volunteers. The pH electrode was initially placed in the gastric corpus using pH readings and catheter length only, and the electrode tip was fluoroscopically located before and after the 24-hour study. Only in one study arm was an adjustment of the electrode position allowed, if fluoroscopy showed a position outside the gastric body. Thirty-seven (92%) of all 40 electrodes were in the corpus when placed by pH-metric methods alone. With fluoroscopic guidance, 2 of the 3 electrodes lying outside the corpus could be repositioned as desired. The median night, day or 24-hour gastric pHs measured in the groups with or without replacement of the electrode tip were identical. Displacement after 24-hour measurements did not occur with initially correctly positioned electrodes. Fluoroscopy is not necessary for the verification of the position of electrodes placed by pH-metric techniques in individuals with residual acid secretion, and electrode displacement is rare.