This is a traditional (narrative) review with the objective of highlighting the contribution of obstetric ultrasonography (US) between the 11th and 14th week of pregnancy, commonly called first trimester anomaly scan. In addition to being used for the screening of chromosomal anomalies, US can be employed during this period to confirm or determine gestational age, evaluate fetal anatomy, diagnose malformations, screen major structural abnormalities and genetic syndromes, define the prognosis of pregnancy, diagnose and characterize multiple pregnancies, and screen preeclampsia and intrauterine growth restriction. The most important studies about this subject published between 1990 and 2010 in the Cochrane and PubMed libraries were included. The selected studies can be classified with scientific levels I to III.
First trimester; Obstetric ultrasonography; Fetal malformation; Chromosome aberrations; Nuchal translucency measurement; Pregnancy, multiple; Heart defects, congenital; Pre-eclampsia
