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First Trimester Screening for Congenital Heart Defects
Study Questions:
What is the impact of first trimester screening on the spectrum of congenital heart defects (CHD) later in pregnancy, and on the outcome of fetuses and children born alive with CHD?
Methods:
A retrospective review was performed in Southern Monrovia (a region of the Czech Republic). Fetuses with CHD were studied in three groups. Group I (127 fetuses) included those diagnosed in the first trimester, while Group II (344 fetuses) included those diagnosed only in second trimester screening. Groups I and II were diagnosed between 2007 and 2013, while patients in Group III included 532 fetuses diagnosed in the second trimester between 1996 and 2001, prior to the introduction of first trimester screening. Infants underwent initial screening by their primary obstetrician and were referred for specialized fetal echocardiography if a cardiac anomaly was suspected on initial scan.
Results:
Significant differences were seen in the spectrum of CHDs in Group I as compared with Group II. There were a greater number of comorbidities, CHDs with univentricular outcome, intrauterine deaths, and terminations of pregnancy in group I. In Group III, significantly more cases of CHD with univentricular outcome, intrauterine demise, and early termination were identified in comparison to fetuses diagnosed in the second trimester between 2007 and 2013. The spectrum of CHD seen in the second trimester groups differed after first trimester screening was implemented.
Conclusions:
First trimester screening had a significant impact on the spectrum of CHD and on the outcomes of pregnancies with CHD diagnosed in the second trimester. Early detection of severe forms of CHD and significant comorbidities resulted in an increased pregnancy termination rate in the first trimester.
Perspective:
While first trimester screening for CHD and related comorbidities has been instituted in some areas, second trimester screening remains the standard in many areas, including the United States. First trimester screening may be limited by expertise of the sonographer, quality of equipment, and ability to detect cardiac anomalies in sufficient detail to understand the natural history of the defect. Additionally, some lesions may not become apparent until later in pregnancy. There is likely to be significant variability by country or region as to the impact of first trimester screening on pregnancy outcomes. Only 9.5% of fetuses diagnosed in the first trimester were born alive, as 5.5% died in utero and pregnancy was terminated in 85% fetuses. There are likely to be very different approaches to pregnancy termination based on the presence of CHD or other birth defects from country to country.
Keywords: Abortion, Induced, Comorbidity, Echocardiography, Fetus, Heart Defects, Congenital, Parturition, Pregnancy, Pregnancy Trimester, First, Pregnancy Trimester, Second, Stillbirth
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