A couple of noteworthy features – extensions and clustering – have the potential to improve ICD-11 code data. Extensions are non-diagnostic codes that add flexibility to the classification. They cannot be used alone, but rather are intended to be added to a stem code, replacing ICD-10 adjunct codes. Extension codes are appended to describe laterality, acuity, severity and other dimensions and external causes of injury.
Cluster coding, or combining two or more codes to describe a documented clinical concept, is how ICD-11 marks codes that are post-coordinated to describe one condition. When a diagnostic statement is broken down into its component parts for simplicity, clustering enables them to be linked in the coded record.
The AAPC, the nation’s largest education and credentialing organization for medical coders and billers, explains it this way:
Cluster coding refers to a convention where a “with” operator, either a forward slash or ampersand, is used to link ICD-011 codes together to create a diagnostic “sentence.”
Diagnosis: Duodenal ulcer with acute hemorrhage