Abstract
Objective. To determine the frequency of echogenic intracardiac focus (EIF) by race/ethnicity.
Methods. We performed a retrospective analysis from January 1996 through June 2003. We reviewed all initial sonograms from 14 to 23 weeks gestation in singleton pregnancies. Mothers on admission for delivery provided race/ethnicity.
Results. There were 8207 ultrasounds and deliveries that met study criteria. There were 4636 (56.5%) Caucasian, 2087 (25.4%) African-American, 1261 (15.4%) Hispanic and 223 (2.7 %) Asian subjects. There were 347 (4.2%) EIF detected. The frequency by race/ ethnicity varied significantly (p
Conclusions. This large, population-based study showed that fetuses born to Asian mothers were significantly more likely to have an EIF. This racial difference should be taken into account when counseling patients about the potential for Down syndrome.
Keywords: Echogenic intracardiac focus, race/ethnicity
Introduction
An echogenic intracardiac focus (EIF) noted in the left ventricle of the fetal heart was first described in 1988 [1,2]. Bromley and colleagues first noted an association of the EIF and Down syndrome in their population of women having midtrimester sonograms [3]. Numerous studies since have described the association of an isolated EIF and aneuploidy, chiefly Down syndrome [4-6]. A meta-analysis of sonographic markers for Down syndrome calculated a likelihood ratio of 2.0 for an echogenic focus to adjust the risk for a fetus with Down syndrome [7]. Previous studies have implicated maternal race and ethnicity as an important risk factor for detecting a fetus with an EIF [8-10]. There is little population-based data investigating the association of race and ethnicity with the incidence of echogenic foci. We sought to determine the variation in the frequency of echogenic intracardiac focus by race/ethnicity.
Methods
We performed a retrospective analysis at Saint Francis Hospital and Medical Center, a tertiary community teaching hospital, matching our ultrasound and delivery databases. We examined all ultrasound exams from January 1996 through June 2003. We included all initial sonograms from 14-23 weeks gestation in singleton pregnancies. An EIF was noted if it was as echogenic as bone in any chamber of the fetal heart. Known aneuploid fetuses were excluded. All ultrasound exams were performed in a single AIUM accredited unit with a general population referral base. Mothers upon admission for delivery provided race/ethnicity. Descriptive statistics and Chi-square were performed. The study was approved by our hospital’s IRB.
Results
There were 8207 ultrasounds and deliveries that met study criteria. Down syndrome was known in 40 cases (approximate prevalence 1:200) and these were eliminated from the analysis. Sixty- five percent of the ultrasounds were performed for routine indications such as fetal anatomical survey or for an estimation of gestational age; 34% were targeted ultrasounds. There were 4636 (56.5%) Caucasian, 2087 (25.4%) African-American, 1261 (15.4%) Hispanic and 223 (2.7%) Asian subjects. Broken down by race/ ethnicity, 50% of the scans performed in the Caucasian population were targeted versus 44% for the Asian, 33% of the African- American, and 22% of the Hispanic populations, respectively. EIF were detected in 347 (4.2%) fetuses. The frequency by race/ ethnicity varied significantly (p
Discussion
We have shown that maternal race/ethnicity significantly affects the incidence of sonographically detected fetal echogenic intracardiac focus.
In a prospective series, Shipp and colleagues found a 30.4%, 5.9%, 10.5%, and 11.1% incidence of echogenic intracardiac foci in Asian, black, white and unknown race mothers, respectively [10]. Of the 489 subjects in the study, 46 were Asian and 400 white. In a case control study by Ehrenberg and colleagues, Asian mothers were approximately 5 times more likely to have a fetal echogenic intracardiac focus [9]. However, there were only 103 cases and controls in this study with Asians accounting for about 10% of the subjects. Finally, a small study of Hispanic women in Puerto Rico found 9 echogenic intracardiac foci in 485 normal fetuses (1.9%) [8].
Our study has the advantage of many more subjects than previously reported. Our subjects are a representation of our local population’s racial/ethnic mix. We confirmed the previous report by Shipp and colleagues that Asian race is significantly associated with the detection of an echogenic intracardiac focus, however our percentage of echogenic intracardiac focus in Asian women is considerably smaller than that found in their report. The age of our Asian population with an EIF was 30.6 (SD 5.6) years old compared to 32.7 (SD 5.7) for our Caucasian population indicating that maternal age was not a factor in the higher incidence of EIF.
Figure 1. Incidence of EIF by race/ethnicity.
While this is a retrospective study, the data was collected prospectively and maintained at our institution over a long period of time. While this may introduce ascertainment bias, it would most likely be randomly spread throughout the study population with little impact on the results. Additionally, only women who had an ultrasound and delivered at our institution were included in our analysis. Since our institution provides tertiary care, few patients are transported or deliver elsewhere. The loss of these patients; however, may introduce some selection bias. Our larger numbers may provide a better estimation of the influence of race and ethnicity than previously published. This racial difference should be taken into account when counseling patients about the potential for Down syndrome. With the higher incidence of EIF in the fetuses of Asian mothers, the likelihood ratio for increasing the risk of Down syndrome may be further reduced or become insignificant. Further investigation is needed to determine appropriate likelihood ratios for race/ ethnicity if EIF is used to screen for Down syndrome.
References
1. Levy DW, Mintz MC. The left ventricular echogenic focus: A normal finding. Am J Roentgenol 1988;150:85-86.
2. Schechter AG, Fakhry J, Shapiro LR, Gewitz MH. The left ventricular echogenic focus. Am J Roentgenol 1988;150: 1445-1446.
3. Bromley B, Lieberman E, Laboda L, Benacerraf BR. Echogenic intracardiac focus: A sonographic sign for fetal Down syndrome. Obstet Gynecol 1995;86:998-1001.
4. Nyberg DA, Souter VL. Sonographic markers of fetal trisomies: second trimester. J Ultrasound Med 2001;20: 655-674.
5. Bromley B, lieberman E, Shipp TD, Richardson M, Benacerraf BR. Significance of an echogenic intracardiac focus in fetuses at high and low risk for aneuploidy. J Ultrasound Med 1998;17:127-131.
6. Nyberg DA, Souter VL, El-Bastawissi A, Young S, Luthhardt F, Luthy DA. Isolated sonographic markers for detection of fetal Down syndrome in the second trimester of pregnancy. J Ultrasound Med 2001;20:1053-1063.
7. Smith-Bindman R, Hosmer W, Feldstein VA, Deeks JJ, Goldberg JD. second-trimester ultrasound to detect fetuses with Down syndrome: A meta-analysis. JAMA 2001;285: 1044-1055.
8. De la Vega AVM. Incidence of fetal echogenic intracardiac foci in a Hispanic population. P R Health Sci J 2002;21:349-350.
9. Ehrenberg HM, Fischer RL, Hediger ML, Hansen C, Stine D. Are maternal and sonographic factors associated with the detection of a fetal echogenic cardiac focus? J Ultrasound Med 2001;20:1047-1052.
10. Shipp TD, Bromley B, lieberman E, Benacerraf BR. The frequency of the detection of fetal echogenic intracardiac foci with respect to maternal race. Ultrasound Obstet Gynecol 2000;15:460- 462.
ADAM F. BORGIDA1, CHRISTINE MAFFEO2, ELISA A. GIANFERARRI2, ALAN D. BOLNICK2, CAROLYN M. ZELOP3, & JAMES F. X. EGAN2
1 Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Hartford Hospital, Hartford, CT, USA, 2 Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Connecticut School of Medicine, Farmington, CT, USA, and 3 Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Saint Francis Hospital and Medical Center, Hartford, CT, USA
Correspondence: Adam F. Borgida, MD, 85 Jefferson St. #625, Hartford, CT 06102, USA. Tel: + 1 8605452884. Fax: + 1 8605453396. E- mail: [email protected]
Copyright CRC Press Jul 2005
Comments