Natural Language Interface is used as the first step to access to the medical database. There are hierarchical and other semantic links between concepts which allows a contextual extension of the research by conceptual proximity. Faced to a free text user request, the system return a list of recognized entities which are the entry points to the database. It is used to index all medical texts by ADM entities dictionary. We must point out here that the Pragmatic knowledges are taken into account through the semantic analysis.
Morphological analysis enables to divide the text into sentences.
As regards medical texts, trying to use complete syntactic analyser is illusive because texts often do not comply with natural language's grammar. This segmentor is based on strong markers which are Verb, conjunction, preposition, predicative expression and punctuation sign. In the Semantic analysis, the main objective is to detect concepts or phrases according to their meaning. This detection implies to solve problems concerning medical language like polysemy and paraphrase. Solving this problem is possible by determining the context of the word for polysemy and for the paraphrase, by identifying compound and associated words.