['Accurate catheter placement in children for esophageal pH monitoring is performed following an endoscopy using a mathematical formula followed by confirmatory radiograph.', 'To determine if endoscopic visualization of the gastroesophageal junction can be used for sensor placement without the need for confirmatory radiograph.', 'Sixty-four catheters were placed using the Strobel formula method and 57 catheters were placed by visualization.', 'With the formula method, 66% of children required probe adjustment compared with 7% when the probe was placed by direct visualization (p < .005).'] Is placement of pH probes during upper endoscopy : direct visualization accurate?