Echogenic intracardiac focus: a sonographic sign for fetal Down syndrome.

OBJECTIVE

To determine whether an echogenic intracardiac focus identified in the second-trimester fetus is related to an increased risk of Down syndrome.

METHODS

During a 10-month period, all women with singleton gestations who underwent second-trimester genetic amniocentesis for non-imaging indications were evaluated prospectively by prenatal sonography. The presence or absence of an echogenic intracardiac focus was noted. Karyotypic information was obtained on each fetus.

RESULTS

Among the 1334 patients in the study group, 66 fetuses (4.9%) had an echogenic intracardiac focus. Four of 22 fetuses (18%) with trisomy 21 had an echogenic intracardiac focus, compared with 62 (4.7%) of 1312 fetuses without Down syndrome who also had an echogenic intracardiac focus (P = .004). Sonographic identification of an echogenic intracardiac focus was associated with a fourfold increased risk of Down syndrome (risk ratio 4.3, 95% confidence interval 1.5-12.3). The overall prevalence of Down syndrome in our study population was 1.6%. The sensitivity, specificity, and positive predictive value for using the presence of an echogenic intracardiac focus to identify a fetus with Down syndrome was 18.2, 95.3, and 6.1%, respectively. Extrapolating to a lower risk population, the positive predictive value of an echogenic intracardiac focus for detecting Down syndrome in patients at an age-based risk of one in 250, one in 500, and one in 1000 was calculated to be 1.53, 0.77, and 0.39% respectively.

CONCLUSION

Fetuses with an echogenic intracardiac focus have a significantly increased risk of Down syndrome. Although most fetuses with this finding are normal, patients carrying fetuses with an echogenic intracardiac focus should be counseled about the increased risk of trisomy 21.