Intracardiac echogenic focus and trisomy 21 in a population previously evaluated by first-trimester combined screening.

OBJECTIVE

To determine the relation between intracardiac echogenic focus (ICEF) and trisomy 21 in a population of fetuses previously evaluated by first-trimester combined screening.

DESIGN

Prospective study to evaluate the prevalence of trisomy 21 for four groups of pregnancies: those with isolated ICEF, those with ICEF and positive first-trimester combined screening, those with ICEF and other ultrasound markers, and those with ICEF, positive first-trimester combined screening and other ultrasound markers.

SETTING

Teaching hospital.

POPULATION: A total of 7,118 fetuses received first-trimester combined screening and a second-trimester fetal anatomical scan.

METHODS

Amniocentesis for karyotyping was offered for those with positive result of first-trimester combined screening, and for those with the diagnosis of ICEF or other fetal chromosomal aneuploidy ultrasound markers in mid-trimester detailed fetal anatomical scans.

MAIN OUTCOME MEASURES: The prevalence of trisomy 21 in each group.

RESULTS

For the entire study population, 25 trisomy 21 cases were diagnosed prenatally (prevalence, 0.35%). Among fetuses with positive first-trimester combined screening results, the likelihood ratio of trisomy 21 was significantly increased for those with, as compared to without, ICEF (3.5 vs. 0.80, p = 0.012). However, among fetuses with negative first-trimester combined screening results, the likelihood ratios of trisomy 21 did not differ significantly between those with and without ICEF.

CONCLUSION

In pregnancies complicated by isolated ICEF but lacking additional anomalies on ultrasonographic examination and exhibiting negative first-trimester combined screening results, fetal karyotyping is not indicated.