· 91010 Esophageal motility (manometric study of the esophagus and/or gastroesophageal junction) study with interpretation and report. 91020 Gastric motility (manometric) studies ICD 10 Code Description. K21.0 Gastro-esophageal reflux disease with esophagitis K21.9 Gastro-esophageal reflux disease without esophagitis K22.0 Achalasia of ….