[Prevalence of congenital abnormalities identified in fetuses with 13, 18 and 21 chromosomal trisomy].

Purpose: To describe the prevalence of malformations found in fetuses with trisomy of chromosomes 13, 18 and 21 by identifying the most frequent within each condition.

Methods: A retrospective cross-sectional study with the analysis of trisomy cases of chromosomes 13, 18 and 21 diagnosed through fetal karyotype obtained by amniocentesis/cordocentesis, between October 1994 and May 2014, at a Teaching Hospital in Brazil Southern Region. Malformations identified through morphological ultrasonography were described and, subsequently, confirmed in newborn examinations and/or fetal autopsy.