International Journal of Medical Informatics 64 (2001) 223 – 240 Standardized terminological services enabling semantic interoperability between distributed and heterogeneous systems  Josef Ingenerf a, *, Jo ¨ rg Reiner b , Bettina Seik a a Institute for Medical Informatics, Medical Uniersity of Lu ¨beck, Ratzeburger Allee 160, 23538 Lubeck, Germany b GSF -Medis -Institute, Postfach 1129, 85758 Neuherberg, Germany Abstract The interconnection of heterogeneous computer applications in medicine raises the issue of semantic interoperabil- ity, going beyond traditional approaches of terminological standardization in basically three aspects. First, the variety of medical vocabularies that currently coexist in different domains is a major barrier for the integration of autonomously developed applications. Fortunately, with the Unified Medical Language System (UMLS) there are machine-readable terminological sources that cover and integrate most of the existing medical vocabularies. Second, the exchanged data need to be processed by a machine for different purposes like patient data integration, access to literature and knowledge bases as well as clinical audit and research. Medical vocabularies provided as passive dictionaries are no longer sufficient. Software system developers should take advantage of terminological services for refining user queries, for mapping the user’s terms to appropriate medical vocabularies etc. Third, the services should be accessible uniformly and transparently. In the CORBAmed initiative a proposal for a standardized interface for querying and accessing computerized medical terminology resources was created. Based on the mentioned principles the MUSTANG system (Medical UMLS based Terminology Server for Authoring, Navigating and Guiding the Retrieval to Heterogeneous Knowledge Sources) has been developed. It is implemented on a Windows NT platform using the ORACLE database management and development software. The terminological services are accessible via multiple interfaces. The MUSTANG-System and the experiences with using terminological services in practice are described. Opposed to other levels of standardization like syntactical message standards there is much more a hesitation in the use of standardized terminology. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Terminology; Open distributed systems; Medical records; Standards www.elsevier.com/locate/ijmedinf 1. Introduction The process of healthcare has become more and more a distributed process with increasing needs for cooperation and commu- nication in a shared-care scenery. The basic  Selected paper of the conference MIE2000, Hanover, Au- gust 2000. * Corresponding author. Tel.: +49-451-500-6625; fax: + 49-451-500-6610. E-mail address: ingenerf@medinf.mu-luebeck.de (J. In- generf). 1386-5056/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII:S1386-5056(01)00211-8