How important is a cardiac echogenic focus in a routine fetal examination?

Intracardiac echogenic foci are very frequent findings during routine fetal ultrasound examination and sometimes a reason for referral of patients for fetal echocardiography.

To assess the incidence of echogenic intracardiac foci in a mixed population of fetuses at high and low risk for congenital heart defects, and to determine whether the association between echogenic foci and congenital heart disease is stronger than in the general fetal population.

Retrospective evaluation of clinical files at two fetal cardiology referral centers, during the last two years. All cases that had at least one echogenic focus were selected for our study. Maternal age, gestational age, reason for referral, location and number of echogenic foci, chromosomal abnormalities and cardiac defects were analyzed. As previous studies suggest increased risk of trisomy associated with echogenic foci and considering that congenital heart defects are more frequent in fetuses with trisomy 21, we excluded all fetuses with aneuploidy from our study.

Thus, 753 clinical files were reviewed, of which 61 (8.1%) had a fetus with at least one echogenic focus. Mean maternal age was 29.0 years (minimum--19 years, maximum--43 years). Mean gestational age at the time of the examination was 23.4 weeks (minimum--19 weeks, maximum--31 weeks). In 48.0% the reason for referral for fetal echocardiography was the existence of echogenic foci previously seen during a routine maternal examination. Increased nuchal translucency in 13.0% of pregnant women, maternal age in 10.0%, family history of congenital heart defects in 8.4%, suspicion of cardiac malformation in the obstetric scan in 4.2%, twinning in 4.0%, history of miscarriage in 2.1% and maternal pathology in 10.3% were other referral reasons. In 53 cases a single echogenic focus was found, 44 of them inside the left ventricle and 9 in the right ventricle. Multiple echogenic foci were found in the different heart chambers in the eight remaining cases. Fifty-six fetuses had a structurally normal heart and in five (8.1%) a cardiac defect was found.

Echogenic foci are commonly seen inside heart chambers during routine fetal heart scanning, the left ventricle being the most frequent location. Although they probably represent a normal variant of papillary muscle development their presence should be interpreted as a possible risk for congenital heart defects.