Retrospective analysis of 2054 cases from 24 hospitals underwent ultrasonic consultation in a tertiary prenatal diagnosis center in Beijing, China.

Our study demonstrated that the discordance of the first single signs was relatively low in the first trimester and higher in the second and third trimesters. The number of sonographers could be increased to ensure timeliness, strengthen training for those with poor concordance rates by referring to appropriate guidelines, and reduce ultrasonic consultation for those with high consistency after further research to save medical resources.