FETAL HEART SCREENING IN LOW-RISK PREGNANCIES

The aim of this study was to assess whether a screening program for fetal cardiac malformations is justified in a low-risk population, and which factors influence its accuracy. The fetal heart was evaluated in 7024 pregnant women at 20-22 weeks, and evaluation was repeated at a more advanced gestational age in 9% of cases. Cardiological follow-up wa continued postnatally until 2 years of age. The overall prevalence of cardiac anomaly was 0.93%. The incidences of major and minor defects were 0.44% and 0.48%, respectively. There were 23 true positives (0.33%): in 20 cases, the diagnosis was made in the second trimester, and 13 women (655) chose termination of pregnancy. Seventeen of the 20 cases identified in the second trimester were serious malformations. There were 42 false negatives (0.60%). Of these, 12 has signs of cardiac dysfunction at birth or within the 1st month of life, and three of them died as a result of their cardiac anomaly. There were eight false positives (0.11%), all of a minor type. Six abnormal karyotypes, out of a total of 21 performed in the true-positive group (28.5%), were found. In addition, five of the 42 newborns in the false-negative group has trisomy 21. The overall sensitivity was 35.45, and 61.3% for major defects. The accuracy in two distinct periods was estimated because the level of experience of the operators was different: sensitivity was 45.2% in period 1 (1986-88) (77.8% for major defects). We conclude that a fetal heart screening program in the obstetric population is justified. It defines a high-risk group for karyotyping, allows planning of delivery in a tertiary center or the choice of terminating the pregnancy for the parents and appears to have a positive cost-benefit ratio. A crucial factor is th level of training and experience of the operators , who need specific teaching support.