Relationship of isolated fetal intracardiac echogenic focus to trisomy 21 at the mid-trimester sonogram in women younger than 35 years.

OBJECTIVE

To determine whether an isolated echogenic intracardiac focus in the fetal heart in the mid-trimester (16-24 weeks) in women aged 18-34 years of age is associated with trisomy 21.

METHOD: This was a prospective population-based observational study. A search of all obstetric sonograms performed in our region from January 1997 to December 1999 was carried out. From 12,373 pregnancies we identified 267 cases of echogenic foci in the fetal heart. Trisomy 21 was detected in 38 deliveries (0.31%). An echogenic focus was seen in 193 of the 9167 women < 35 years of age who had an obstetric sonogram at 16-24 weeks' gestation, and an echogenic focus was seen in 67 of the 1968 women > 35 years. The study group comprised the 149 women aged 18-34 years who had an echogenic focus in the fetal heart as the only abnormality at an obstetric sonogram performed at 16-24 weeks' gestation.

RESULTS

There were no abnormal outcomes or cases of trisomy 21 among the 149 pregnancies with an echogenic focus as an isolated finding in women aged 18-34 years (0% (95% confidence interval, 0.00-2.43)). The prevalence of isolated echogenic focus was 1.6% for women < 35 and 1.8% for women >or= 35 years old. Of the 25 fetuses with trisomy 21 undergoing an obstetric sonogram at any gestational age, five (20%) had an echogenic focus. An isolated echogenic focus was present in one fetus with trisomy 21 seen at 26 weeks' gestation in a 17-year-old mother. Echogenic foci were single and in the left ventricle in 84.7% of cases.

CONCLUSION

An isolated echogenic focus in the fetal heart at mid-trimester ultrasound in women aged 18-34 years is not associated with increased risk for trisomy 21.