OPS (in earlier versions: OPS-301), the Operationen- und Prozedurenschlüssel (Operation and Procedure Classification System) is the German modification of the International Classification of Procedures in Medicine (ICPM). For German hospitals it is currently the official coding system for medical procedures. Apart from its use for clinical controlling and performance statistics it is a basis for inpatient claims processing within the German Diagnosis-related Groups (G-DRG) system. Yearly OPS releases are produced by DIMDI (Deutsches Institut für Medizinische Dokumentation und Information). Besides OPS, G-DRG also requires disease codes based on ICD-10-GM is (the German Modification of the current WHO standard).
Basis for OPS was the Dutch ICPM-DE, from which the procedure classification OPS-301 according to §301 SGB V was created. Version 1.0 was published in October 1994 and became effective on January 1, 1995. Originally a subset of ICPM, OPS-301 has been expanded by a significant number of national codes since version 2.0 (effective in 2001). The OPS classification gained an enormous importance with the introduction of the G-DRG flat rate system in 2004.
In 2005, the suffix "-301" was omitted, because the application of OPS was no longer limited to the cases regulated by §301 SGB V, being extended to outpatient procedures in hospitals (§115b SGB V) and outpatient care by private physicians (§295 SGB V).