Diagnóstico precoz de los trastornos del espectro autista en edad temprana (18-36 meses)

there is a delay in the early identification of the autism spectrum disorders (asd). many factors contribute to this delay: questions concerning the definition that faces a challenge due to the growing body of research on early symptoms; for instance, the heterogeneity and complexity of the symptoms in early age and the lack of professional training in the early detection of asd, among others. besides, there are few instruments validated for spanish and portuguese. the objective of this article is to discuss the possible factors that interfere in the process of the early diagnosis of the autism spectrum disorders. a non sistematic bibliographic search was done, through medline, lilacs and cochrane library, using the following key-words: autism, autism spectrum disorders, screening tools, childhood development disorders, assessment, early diagnosis, developmental disabilities, pervasive developmental disorder, besides similar key-words in spanish. there was a selection of 58 articles according to their relevance and contribution to the pediatric knowledge of the theme at the authors' discretion. symptoms as lack of joint attention, not orienting to name, lack of protodeclaratives and lack of symbolic play must be taken into account and should demand referring to specific detection. the stereotyped and repetitive behaviors, although characteristic, may not appear at an early age. the coexistence of other morbidities is frequent, and demands search for other disorders besides asd. the diagnosis at two years of age must be interpreted with care, using different sources of information besides the structured and non structured tests. most important, the child must be evaluated regarding the non-verbal behavior as joint attention, play and imitation. at three years, the usage of formal and structured instruments to evaluate asd has good correlation with the outcomes at seven and at nine years of age. these and other questions concerning the early detection of asd are discu