Clinical implementation of first trimester screening for congenital heart defects.

Objective: To examine the feasibility and performance of implementing a standardized fetal cardiac scan at the time of a routine first-trimester ultrasound scan.

Method: A retrospective, single-center study in an unselected population between March 2021 and July 2022. A standardized cardiac scan protocol consisting of a four-chamber and 3-vessel trachea view with color Doppler was implemented as part of the routine first-trimester scan. Sonographers were asked to categorize the fetal heart anatomy. Data were stratified into two groups based on the possibility of evaluating the fetal heart. The influence of maternal and fetal characteristics and the detection of major congenital heart disease were investigated.

Results: A total of 5083 fetuses were included. The fetal heart evaluation was completed in 84.9%. The proportion of successful scans increased throughout the study period from 76% in the first month to 92% in the last month. High maternal body mass index and early gestational age at scan significantly decreased the feasibility. The first-trimester detection of major congenital heart defects was 7/16, of which four cases were identified by the cardiac scan protocol with no false-positive cases.

Conclusion: First-trimester evaluation of the fetal heart by a standardized scan protocol is feasible to implement in daily practice. It can contribute to the earlier detection of congenital heart defects at a very low false positive rate.