Echogenic intracardiac focus in 2nd-trimester fetuses with trisomy 21: Usefulness as a US marker

PURPOSE: To determine whether there is a relationship between the presence of an echogenic intracardiac focus in 2nd-trimester fetuses and trisomy 21 (Down syn- drome). MATERIALS AND METHODS: A complete genetic ultrasonographic (US) scan was ob tained in 3,303 consecutive fetuses with an estimated gestational age of 14 .0- 24.0 weeks (mean +/- SD, 17.1 weeks +/- 1.75). US was performed in a pr ospective fashion without any knowledge of karyotype and included assessmen t of any potential echogenic intracardiac focus tie, calcified papillary mu scle). Karyotypes were obtained in all fetuses. Maternal ages ranged from 1 3.0 to 47.4 years (mean, 35.1 years +/- 5.1). The prevalence of Down syndro me in this population was 1.6% (53 of 3,303 fetuses). RESULTS: An echogenic intracardiac focus was seen in 147 of the 3,192 karyo typically normal fetuses (4.6%) and 16 of the 53 fetuses with trisomy 21 (3 0%). The positive predictive value (PPV) of an echogenic intracardiac focus in this high-risk population was 9.8%; sensitivity, 30%; specificity, 95%; likelihood ratio, 6.6; and relative risk (RR), 8.2 (P < .001). For a sonog raphically isolated echogenic intracardiac focus, the PPV was 3.7%; sensiti vity, 19%; specificity, 95%; likelihood ratio, 4.2; and RR, 4.8 (P =.002). CONCLUSION: A sonographically isolated echogenic intracardiac focus (no oth er anomalies or markers noted on a complete genetic sonogram) was associate d in our high-risk population with a 4.8-fold (95% Cl: 1.8, 12.5) increase in RR for trisomy 21 (P =.002).