Since publication of Chicago Classification version 3.0 in 2015, the clinical and research applications of high-resolution manometry (HRM) have expanded. In order to update the Chicago Classification, an International HRM Working Group consisting of 52 diverse experts worked for two years and utilized formally validated methodologies. Compared with the prior iteration, there are four key modifications in Chicago Classification version 4.0 (CCv4.0). First, further manometric and non-manometric evaluation is required to arrive at a conclusive, actionable diagnosis of esophagogastric junction (EGJ) outflow obstruction (EGJOO). Second, EGJOO, distal esophageal spasm, and hypercontractile esophagus are three manometric patterns that must be accompanied by obstructive esophageal symptoms of dysphagia and/or non-cardiac chest pain to be considered clinically relevant. Third, the standardized manometric protocol should ideally include supine and upright positions as well as additional manometric maneuvers such as the multiple rapid swallows and rapid drink challenge. Solid test swallows, postprandial testing, and pharmacologic provocation can also be considered for particular conditions. Finally, the definition of ineffective esophageal motility is more stringent and now encompasses fragmented peristalsis. Hence, CCv4.0 no longer distinguishes between major versus minor motility disorders but simply separates disorders of EGJ outflow from disorders of peristalsis.
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