ObjectiveTo determine whether karyotype is indicated when fetal heart echogenic foci are encountered on prenatal sonogram.MehtodsPregnant women who presented at two large district hospitals in Israel that treat 7200 gravidas per year, and in whom fetal heart echogenic foci were diagnosed, were studied prospectively. Identified cases had detailed prenatal and postnatal echocardiographic examinations, and pregnancy outcome was assessed.ResultsDuring 18 months, 2214 low-risk pregnant women were examined sonographically, and 163 (7.4%) cases of fetal heart echogenic foci were detected at the first transvaginal sonography at 13-16 week's gestation. On a repeat scan at 20-22 weeks' gestation, 59.5% of the foci could not be identified, leaving only 66 (3%) cases for postnatal evaluation. Left ventricle-right ventricle ratio for location of the fetal heart echogenic foci was 3:1; 4.9% of all cases had bilateral findings. The karyotypes of 16 fetuses were normal and no additional abnormalities were found. The remaining 50 cases were normal in appearance at delivery without any features that suggested trisomy 21. A review of the English language literature revealed that six of 489 cases with fetal heart echogenic foci (1.2%) had trisomy 21. However, statistical analysis of a hypothetical sample that produced these six cases revealed that the calculated risk of trisomy 21 in a fetus with fetal heart echogenic foci is about 0.002%.ConclusionKaryotyping is unwarranted in the midtrimester fetus with incidental findings of fetal heart echogenic foci.