First-trimester screening with or without biochemistry is often thought of as a screening test for high-risk patients and those of advanced maternal age. It is a useful screening tool that is being offered more frequently to the low-risk population. This case demonstrates the sonographic findings associated with Trisomy 13 in a low-risk patient during her first trimester of pregnancy and the evolution of these findings throughout gestation. It also stresses the importance of evaluating fetal anatomy during scans performed in the first trimester, as the clinical management of the patient will be quite different for those with fetal anomalies than those without.
