Chicago Classification ver. 4.0: Diagnosis of Achalasia and Esophagogastric Junction Outflow Obstruction

Achalasia is a common esophageal motility disorder characterized by inappropriate relaxation of the lower esophageal sphincter and a loss of normal peristalsis in the esophageal body. The newly suggested Chicago Classification ver. 4.0 recommends conclusive diagnoses of types 1, 2, and 3. A conclusive diagnosis of type 3 achalasia requires no appreciable peristalsis compared to the previously used ver. 3.0. In the case of inconclusive diagnosis of achalasia, additional tests, including timed barium esophagogram (TBE) or functional lumen imaging probe (FLIP), are strongly recommended in ver. 4.0. Esophagogastric junction outflow obstruction (EGJOO) in Chicago Classification ver. 3.0 was defined as an elevated median integrated relaxation pressure (IRP) without evidence of achalasia. On the other hand, the diagnosis of EGJOO in Chicago Classification ver. 4.0 requires elevated IRP in both positions, elevated intrabolus pressure, positive clinical symptoms, and additional positive test by TBE or FLIP. The newly suggested Chicago Classification Classification ver. 4.0 will be helpful in an accurate diagnosis of esophageal motility disorders, including achalasia and EGJOO.