Detailed fetal anatomy assessment in the first trimester at 11, 12 and 13 weeks of gestation

Objective: The aim of the present observational study was to evaluate the feasibility of a morphological scan and determine the detection rate of fetal organs, structures and systems in the first trimester of pregnancy. Methods: 977 single pregnant women attending our Fetal Medicine Section to undergo first trimester screening for aneuploidies were enrolled and divided into three groups depending on gestational age and crown-rump-length measurement. Scans targeted on a total of 26 fetal anatomical structures were performed by a single operator. Results: The overall detection rate was 96% at 11 weeks and reached 100% at 12 and 13 weeks, with a significant statistical difference between 11 and 12/13 weeks for the majority of the investigated fetal anatomical structures. Conclusions: Evaluation of most part of the fetal anatomical structures is feasible with high accuracy in the first trimester. Visualization of the majority of the targeted fetal organs improves from 11 to 13 weeks.