Objective: To determine the prevalence of isolated echogenic intracardiac foci and the subsequent risk for Down's syndrome at 18-23 weeks in an unselected obstetric population.
Design: Prospective study.
Setting: A district general hospital serving a routine obstetric population.
Participants: 16,917 pregnant women who underwent a routine ultrasound screening at 18-23 weeks of gestation between November 1994 and August 1998.
Methods: All women were offered screening for Down's syndrome by nuchal translucency or maternal serum biochemistry. The prevalence of isolated echogenic intracardiac foci was determined and the relative risk for Down's syndrome was calculated for different ultrasound findings.
Results: The combined sensitivity of age, nuchal translucency and maternal serum biochemistry for Down's syndrome was 84% (27/32). The relative risk for Down's syndrome was 0.17 (95% CI 0.07-0.41) for the women with normal scan findings at 18-23 weeks. The prevalence of isolated echogenic intracardiac foci at 18-23 weeks was 0.9% (144/16,917). None of these pregnancies were affected by Down's syndrome.
Conclusion: The significance of the association between isolated echogenic intracardiac foci and Down's syndrome is a matter of ongoing debate. The data of this study suggest that in an unselected obstetric population with prior, effective, routine Down's syndrome screening, the association between isolated echogenic intracardiac foci and Down's syndrome is no longer significant.