Use of genetic sonography for adjusting the risk for fetal Down syndrome

[A pragmatic comparison of fetal biometry curves]

INTRODUCTION

The fetal biometrics charts recommended in France for ultrasound screening include measurements of head circumference (HC), biparietal diameter (BIP), abdominal circumference (AC) and femur length (FL). New international growth standards have been recommended since 2022. The aim of this work is to quantitatively describe the differences between these biometric curves.

METHODS

The biometry curves from the French College for Fetal Ultrasound, OMS and INTERGROWTH-21 are pragmatically compared based on their original quantile regression equations (superposition and quantification of differences in millimeters and in proportion) for different percentiles of clinical interest.

RESULTS

Compared with the new charts, CFEF underestimates HC<-3DS and AC<10eP. The proportions of differences between the CFEF and INTERGROWTH-21 or WHO curves always remained <5%. The proportions of difference of the 3rd percentile of HC and FL, 10th and 90th percentile of AC were always lower than 2%, 2%, 5% and 4% respectively, between OMS and INTERGROWTH-21.

CONCLUSION

The switch to prescriptive standards suggests an improvement in the detection of fetuses with AC<10th percentile, an improvement in the detection of prenatal onset microcephaly, with no argument for a decrease in the detection rate of severe constitutional bone disease or modification of obstetrical guidelines.

Novel method for trisomy 21 screening in the first trimester of pregnancy: fetal brain angle

OBJECTIVES

The present study was performed to examine the utility of a new first trimester marker called the "brain angle" (BA) in screening for trisomy 21. We postulate that differences in the midbrain anatomy between euploid fetuses and those that are affected by trisomy 21 are reflected in changes in BA measurements.

METHODS

In fetuses at 11⁺⁰-13⁺⁶ weeks of gestations, which were at high risk for trisomy 21, the angle was measured between the line crossing the thalamus and mesencephalon cranial border tangentially and the line crossing the brainstem lower limit. This angle was compared between fetuses with trisomy 21 (based on karyotyping) and those with a normal karyotype.

RESULTS

Trisomy 21 was detected in 45 (8%) of 560 fetuses. Receiver operating characteristic analysis showed that, at BA≥94°, the sensitivity and specificity for determining trisomy 21 were 97.8% (95% CI=88.2-99.9%) and 100% (95% CI=99.2-100%), respectively.

CONCLUSIONS

Fetal BA appears to be a promising new first trimester marker in screening for trisomy 21.

Foetal Ureteric Calculus Producing Hydronephrosis and Hydroureter

Dilatation of foetal urinary collecting system is common. But cause of obstruction, if any, arise from soft tissues or developmental abnormalities of urinary tract or other paradox. A prenatal diagnosis of a 'calculus' inside ureter producing obstruction and ultimate back pressure changes in collecting system of a foetus is not reported so far. Other than inborn error of metabolism, what aetiological factors lead to this, are a matter of concern and great research. Here kidneys are not dysplastic. Amniotic fluid volume remains normal. Antenatal administration of calcium either orally or parenterally could be a contributory factor as it promotes nephrocalcinosis; and uretric calculus has it's origin in kidneys as believed. There is no maternal symptom related to this entity. Here we report a unique case of foetal ureterolithiasis producing hydroureter and hydronephrosis.

Clinical Practice Guidelines for Prenatal Aneuploidy Screening and Diagnostic Testing from Korean Society of Maternal-Fetal Medicine: (1) Prenatal Aneuploidy Screening

In 2019, the Korean Society of Maternal-Fetal Medicine developed the first Korean clinical practice guidelines for prenatal aneuploidy screening and diagnostic testing. These guidelines were developed by adapting established clinical practice guidelines in other countries that were searched systematically, and the guidelines aim to assist in decision making of healthcare providers providing prenatal care and to be used as a source for education and communication with pregnant women in Korea. This article delineates clinical practice guidelines specifically for maternal serum screening for fetal aneuploidy and cell-free DNA (cfDNA) screening. A total of 19 key questions (12 for maternal serum and 7 for cfDNA screening) were defined. The main recommendations are: 1) Pregnant women should be informed of common fetal aneuploidy that can be detected, risks for chromosomal abnormality according to the maternal age, detection rate and false positive rate for common fetal aneuploidy with each screening test, limitations, as well as the benefits and risks of invasive diagnostic testing, 2) It is ideal to give counseling about prenatal aneuploidy screening and diagnostic testing at the first prenatal visit, and counseling is recommended to be given early in pregnancy, 3) All pregnant women should be informed about maternal serum screening regardless of their age, 4) cfDNA screening can be used for the screening of trisomy 21, 18, 13 and sex-chromosome aneuploidy. It is not recommended for the screening of microdeletion, 5) The optimal timing of cfDNA screening is 10 weeks of gestation and beyond, and 6) cfDNA screening is not recommended for women with multiple gestations. The guideline was reviewed and approved by the Korean Academy of Medical Sciences.

Meta-analysis of validity of echogenic intracardiac foci for calculating the risk of Down syndrome in the second trimester of pregnancy

Echogenic intracardiac foci are a second trimester marker associated with aneuploidy in high-risk populations. The objective of this study is to assess the validity of echogenic intracardiac foci for Down syndrome detection in the second trimester ultrasound scan. A systematic search in major bibliographic databases was carried out (MEDLINE, EMBASE, CINAHL). Twenty-five studies about echogenic intracardiac foci were selected for statistical synthesis in this systematic review. Those 25 considered to be relevant were then subjected to critical reading, following the Critical Appraisal Skills Programme criteria, by at least three independent observers. Then, the published articles were subjected to a meta-analysis. A global sensitivity of 21.8% and a 4.1% false positive rate were obtained. The positive likelihood ratio was 5.08 (95% confidence interval, 4.04-6.41). The subgroups analysis did not reveal statistically significant differences. In conclusion, echogenic intracardiac foci as an isolated marker could be a tool to identify-rather than exclude-the high-risk group of Down syndrome, although it should be noted that it shows low sensitivity.

Maxilla-nasion-mandible (MNM) angle: an indicator to assess fetal facial profile in first-trimester of pregnancy

Objective

The aim of this study was to observe whether there existed significant differences in the maxilla–nasion–mandible angle (MNM) between the first- and second-trimester of pregnancy, and to observe its predictive values for trisomy 18.

Methods

Two experienced ultrasonologists used 2D and 3D ultrasound imaging techniques to obtain the facial sagittal sections of fetuses in the first-trimester of pregnancy (crown-rump length 45–84 mm), respectively, so as to measure MNM.

Results

MNM could be measured in 91 % of normal fetuses, and the measurement differences by different operators in different groups were <1.1°; average MNM was 11.0°, and no significant change was observed in different gestational ages (P = 0.15). The average of MNMs in fetuses with trisomy 18 was 16.6°, which were all higher than the 95th percentile of normal measurement data. The sensitivity and specificity of increased MNM on the abnormal detection of trisomy 18 were 54.7 and 97.4 %, respectively.

Conclusions

The feasibility and reproducibility of measuring MNM in early pregnancy were good. MNM had certain suggestive roles for aneusomic chromosomal abnormalities, especially for fetuses with trisomy 18.

Evaluation of the adequacy of reference charts for the accurate identification of fetuses with bone length below the 5th percentile

AIM

To identify reference charts for femoral and humeral lengths enabling appropriate identification of fetuses <5th percentile in one population.

METHODS

Two samples of fetuses aged 14-40 weeks were selected from our institution's ultrasonographic database. Regression analysis was used to construct reference charts of femoral and humeral lengths based on the local population (n=901). Femur and humerus length measurements from a second sample (n=1240) were transformed into Z-scores using local and previously published equations. Z-score distributions were used to assess the appropriateness of reference curves for our population. Fetuses aged 18-24 weeks with measurements <5th percentile were identified using each reference equation.

RESULTS

For femoral length, one equation other than the local equation yielded Z-score values within the standard normal distribution (P=0.10), but the histogram was skewed to the right. All Z-score distributions for humeral length fell within the normal distribution (P>0.05), but one was skewed to the right. The numbers of fetuses with femoral and humeral lengths <5th percentile in second-trimester ultrasound examinations varied widely among reference equations used.

CONCLUSION

Most reference charts assessed underestimated the number of fetuses with long bone lengths <5th percentile in second-trimester ultrasound examinations and were thus unfit for interpretations of biometric data from the study population.

A new model for providing cell-free DNA and risk assessment for chromosome abnormalities in a public hospital setting

OBJECTIVE

Cell-free DNA (cfDNA) offers highly accurate noninvasive screening for Down syndrome. Incorporating it into routine care is complicated. We present our experience implementing a novel program for cfDNA screening, emphasizing patient education, genetic counseling, and resource management.

STUDY DESIGN

Beginning in January 2013, we initiated a new patient care model in which high-risk patients for aneuploidy received genetic counseling at 12 weeks of gestation. Patients were presented with four pathways for aneuploidy risk assessment and diagnosis: (1) cfDNA; (2) integrated screening; (3) direct-to-invasive testing (chorionic villus sampling or amniocentesis); or (4) no first trimester diagnostic testing/screening. Patients underwent follow-up genetic counseling and detailed ultrasound at 18-20 weeks to review first trimester testing and finalize decision for amniocentesis.

RESULTS

Counseling and second trimester detailed ultrasound were provided to 163 women. Most selected cfDNA screening (69%) over integrated screening (0.6%), direct-to-invasive testing (14.1%), or no screening (16.6%). Amniocentesis rates decreased following implementation of cfDNA screening (19.0% versus 13.0%, P < 0.05).

CONCLUSION

When counseled about screening options, women often chose cfDNA over integrated screening. This program is a model for patient-directed, efficient delivery of a newly available high-level technology in a public health setting. Genetic counseling is an integral part of patient education and determination of plan of care.

Influence of second-trimester ultrasound markers for Down syndrome in pregnant women of advanced maternal age

The objective of the present study was to evaluate the influence of second-trimester ultrasound markers on the incidence of Down syndrome among pregnant women of advanced maternal age. This was a retrospective cohort study on 889 singleton pregnancies between the 14th and 30th weeks, with maternal age ≥ 35 years, which would undergo genetic amniocentesis. The second-trimester ultrasound assessed the following markers: increased nuchal fold thickness, cardiac hyperechogenic focus, mild ventriculomegaly, choroid plexus cysts, uni- or bilateral renal pyelectasis, intestinal hyperechogenicity, single umbilical artery, short femur and humerus length, hand/foot alterations, structural fetal malformation, and congenital heart disease. To investigate differences between the groups with and without markers, nonparametric tests consisting of the chi-square test or Fisher's exact test were used. Moreover, odds ratios with their respective 95% confidence intervals were calculated. Out of the 889 pregnant women, 131 (17.3%) presented markers and 758 (82.7%) did not present markers on the second-trimester ultrasound. Increased nuchal fold (P < 0.001) and structural malformation (P < 0.001) were the markers most associated with Down syndrome. The presence of one marker increased the relative risk 10.5-fold, while the presence of two or more markers increased the risk 13.5-fold. The presence of markers on the second-trimester ultrasound, especially thickened nuchal fold and structural malformation, increased the risk of Down syndrome among pregnant women with advanced maternal age.

Imaging clues in the prenatal diagnosis of syndromes and aneuploidy

Advances in fetal sonography and MRI have increased both the range and diagnostic accuracy of detectable fetal anomalies, with many anomalies detectable earlier in pregnancy. The presence of structural anomalies greatly raises the risk that the fetus has a syndrome or abnormal karyotype. In addition, new techniques in maternal serum screening have greatly increased the ability to identify pregnant patients at risk for anomalies and syndromes. This paper reviews maternal first- and second-trimester serum screening and imaging and covers many of the most common fetal karyotypic and structural anomalies.

Normal ranges for fetal nasal bone length determined by ultrasound at 18-20 weeks of gestation in a multiethnic Australian population

OBJECTIVE

Absence or hypoplasia of the nasal bone is commonly reported in Down syndrome fetuses. We define normal ranges and the 2.5th centile for fetal nasal bone length (NBL) in a multiethnic Australian population at 18-20 weeks of gestation.

METHODS

A prospective cohort study of women attending for a routine anomaly scan. Ethnicity of the patient and their partner was recorded, and the nasal bone was measured three times. Two methods of nasal bone assessment were used to define normal ranges: a single (first) measurement and the mean value of three measurements. Mixed-effects regression models were employed to account for interoperator differences treating sonographers as random effects. Nonparametric methods were used to define the 2.5th centile for gestational age.

RESULTS

A total of 1199 women were included with a mean gestational age 19.1 (SD 0.4; range 18-20) weeks. There is significant linear relationship between NBL and gestational age (P<0.001). The mean of three nasal bone measurements had a smaller standard deviation than single nasal bone measurements. Nonparametric assessment was used to define the 2.5th centile, which is 4.4 mm at 18 weeks and 5.0 mm at 20 weeks of gestation.

CONCLUSIONS

This study provides a reference range for fetal NBL at 18-20 weeks of gestation in an unselected multiethnic Australian population. Whilst NBL increases linearly from 18 to 20 weeks, the data are not normally distributed and nonparametric techniques are required to define the 2.5th centile. The mixed-effects model also accounts for variation in sonographer measurements.

A prospective cross-sectional study to define racial variation in fetal nasal bone length through ultrasound assessment at 18-20 weeks' gestation

OBJECTIVE

An absent or short nasal bone is highly predictive of Down syndrome in Caucasian populations, but Asians may have shorter nasal bones - increasing the false positive rate of screening. We examine differences in nasal bone length (NBL) in Caucasian and Asian populations.

METHODS

This prospective cohort study involved pregnant women attending for their routine anomaly scan at 18-20 weeks' gestation. Ethnicity of the patient and their partner was recorded, and the nasal bone was measured three times. Mean NBL was calculated and used to investigate the effect of ethnicity first with a simple linear regression model and second with a mixed-effects regression model that accounted for variability of measurement between sonographers.

RESULTS

A total of 1087 families were involved in the study, including 592 (54%) Caucasians, 214 (20%) East Asians, 110 (10%) South Asians and 171 (16%) West Asians. Twenty-three sonographers performed the scans with an average of 19 scans each. There is no significant difference in NBL between Caucasian and Asian populations. The mixed-effects model shows that accounting for sonographer variation is important, with 6.7% of the total variance in measurement being related to this random effect.

CONCLUSIONS

There is no significant difference in NBL between Caucasian and Asian populations. It is reasonable to use criteria established in a Caucasian population to define the characteristics of an absent/short nasal bone in Asian fetuses. This finding also removes difficulties in counselling mixed race couples.

The association of maternal BMI with fetal echogenic intracardiac foci and echogenic bowel

OBJECTIVES

To evaluate the impact of maternal body mass index (BMI) as well as maternal ethnicity on the detection of either echogenic intra-cardiac focus (EIF) or echogenic bowel (EB).

METHODS

This prospective study identified 74 uncomplicated singleton fetuses in which EIF and/or EB were detected between 18 and 21 weeks of gestation (i.e. study group). Seventy four consecutively scanned fetuses without EIF or EB, at the same gestational age, were selected as controls. The differences in maternal BMI and maternal ethnicity were compared between the two groups using the chi(2) test, Fisher's exact test, and the Student t-test. A multivariable logistic regression model was constructed to control for confounders. Odds ratios (OR) and their 95% confidence interval (CI) were computed.

RESULTS

The mean maternal BMI was significantly lower in the study group as compared to controls (22.9 +/- 3.1 vs. 28.0 +/- 7.5 kg/m(2), respectively; p < 0.0001). Patients with fetal EIF and/or EB were significantly more likely to be Asians (20.3% vs. 5.4%, OR = 4.5; 95% CI 1.3-16.9). Using a multivariable analysis, controlling for ethnicity, the association between maternal BMI and fetal EIF or EB remained significant (OR = 0.83; 95% CI 0.76-0.91). However, based on this model Asian ethnicity was not an independent risk factor for the detection of EIF and/or EB (OR = 2.6; 95% CI 0.8-8.9).

CONCLUSIONS

Our data suggests an inverse relationship between the maternal BMI and the detection of fetal EIF and/or EB. Moreover, it appears that low maternal BMI, and not Asian ethnicity, is an independent risk factor for the detection of these echogenic fetal findings.

Variation in fetal ultrasound biometry based on differences in fetal ethnicity

OBJECTIVE

The objective of the study was to evaluate whether fetal ultrasound biometry is affected by variation in fetal ethnicity compared with white controls.

STUDY DESIGN

This was a retrospective observational study of ultrasound biometry in pregnant women with accurate gestational age.

RESULTS

Three hundred five white, 370 Asian, 895 part Hawaiian, 76 Pacific Islander, and 311 white Asian fetuses were analyzed. At 18 weeks gestation femur length was significantly shorter in Asian and white Asian. Humerus length was significantly shorter in Asian, part Hawaiian, and white Asian. White genetic sonogram was positive 14% for femur and 15% for humerus. The following was found: Asian 29% femur (odds ratio [OR], 2.58; 95% confidence interval [CI], 1.70-3.92), 25% humerus (OR, 1.86; 95% CI, 1.23-2.82); part Hawaiian 21% femur (OR, 1.67; 95% CI, 1.14-2.45), 23% humerus (OR, 1.64; 95% CI, 1.13-2.38); Pacific Islander 27% femur (OR, 2.37; 95% CI, 1.23-4.54), 33% humerus (OR, 2.76; 95% CI, 1.47-5.14); and white Asian 20% femur (OR, 1.56; 95% CI, 1.01-2.46), 22% humerus (OR, 1.56; 95% CI, 1.01-2.42).

CONCLUSION

Genetic sonogram was screen positive more frequently because of shorter long bone measurements in all nonwhite ethnicities.

Screening for trisomy 21 during the routine second-trimester ultrasound examination in an unselected Chilean population

OBJECTIVE

To evaluate the performance of a detailed ultrasound examination during the second trimester as a screening test for Down syndrome in an unselected Chilean population.

METHODS

This was part of an ongoing longitudinal study. Included were 3071 women with singleton pregnancies who underwent routine ultrasound examination between 21 + 0 and 25 + 6 gestational weeks as a screening test for chromosomal abnormalities and major congenital structural defects, and who were diagnosed as having trisomy 21 or being chromosomally normal. Maternal age, and eight soft markers and cardiac defects associated with Down syndrome were evaluated as a screening test using logistic regression analysis.

RESULTS

The incidence of Down syndrome was 0.6%, and the mean maternal age was 29.4 +/- 6.2 years. At least one of four soft markers (absent nasal bone, nuchal edema, short femur, echogenic foci) and/or cardiac defects was present in 77.8% of Down syndrome fetuses and in 3.1% of normal fetuses. Furthermore, with a false-positive rate of 1%, the detection rate using the combined model of ultrasound markers and maternal age was 72.2%.

CONCLUSIONS

Second-trimester ultrasound markers are able to detect over 70% of Down syndrome fetuses with only a 1% false-positive rate.

Ultrasound Findings After Screening for Down Syndrome Using the Integrated Test

OBJECTIVE

To evaluate the incidence and significance of fetal anomalies and "soft markers" after screening for Down syndrome using the integrated test.

METHODS

This study is a retrospective study of 2,332 women at University College London Hospitals, United Kingdom. All women were screened for Down syndrome by the integrated test. Subsequently, a detailed anomaly scan was performed. All scan reports and screening results were analyzed statistically using SPSS 11.0 software.

RESULTS

Sixty-eight (2.9%) patients were categorized as high risk. There were 12 cases affected by Down syndrome, 10 (10 of 68) in the high-risk group and two (two of 2,264) in the low-risk group. Soft markers or structural anomalies were found in 13.0% of the low-risk group, in 29.4% of the high-risk group, and in 50% of the fetuses affected by Down syndrome. Multiplying the likelihood ratio of each marker with the risk of Down syndrome from the integrated test reduced the false-positive rate of the integrated test from 2.5% to 1.8%, but was accompanied by a reduction in the detection rate from 83% to 75%.

CONCLUSION

Absence of structural anomalies or markers should not prevent offering karyotyping to women in the high-risk group, because this would result in a significant reduction in the detection rate of Down syndrome. Women screened as low risk by the integrated test who have isolated soft markers should not be offered an amniocentesis.

Second trimester prenatal ultrasound for the detection of pregnancies at increased risk of Down syndrome

OBJECTIVE

To determine the association between second trimester ultrasound findings (genetic sonogram) and the risk of Down syndrome.

METHODS

Prospective population-based cohort study of women who were at increased risk of chromosome abnormality based on serum screening.

RESULTS

Overall 9244 women with singleton pregnancies were included, including 245 whose fetuses had Down syndrome. Overall, 15.3% of the women had an abnormal genetic sonogram, including 14.2% of pregnancies with normal fetuses and 53.1% of those with Down syndrome. If the genetic sonogram were normal, the risk that a woman had a fetus with Down syndrome was reduced (likelihood ratio 0.55 [95% CI 0.49, 0.62]) However, if the normal genetic sonogram were used to counsel these high-risk women that they could avoid amniocentesis, approximately half of the cases of Down syndrome (115 of 245) would have been missed. The isolated ultrasound soft markers were the most commonly observed abnormality. These were seen in a high proportion of Down syndrome fetuses (13.9%) and normal fetuses (9.3%). In the absence of a structural anomaly, the isolated ultrasound soft markers of choroid plexus cyst, echogenic bowel, renal pyelectasis, clenched hands, clinodactyly, two-vessel umbilical cord, short femur, and short humerus were not associated with Down syndrome. Nuchal fold thickening was a notable exception, as a thick nuchal fold raised the risk of Down syndrome even when it was seen without an associated structural anomaly.

LIMITATIONS

All women included in this study were at high risk of Down syndrome based on serum screening, and thus the results of this study cannot be used as a basis to modify maternal age-related risk.

CONCLUSIONS

The accuracy of the genetic sonogram is less than previously reported. The genetic sonogram should not be used as a sequential test following serum biochemistry, as this would substantially reduce the prenatal diagnosis of Down syndrome cases. In contrast to prior reports, most isolated soft markers were not associated with Down syndrome.

The mid-trimester genetic sonogram

The genetic sonogram is a composite algorithm combining multiple individual markers to increase Down syndrome risk prediction. Transformation of sonographic information into a standard mathematical format represented an early challenge that has now been surmounted. Using increasingly sophisticated mathematical techniques, individual patient risk can be estimated. High diagnostic accuracy comparable to standard mid-trimester serum algorithms has been reported. Most recently, a few studies have reported the ability to combine serum and biochemical markers to achieve diagnostic accuracy comparable to first-trimester screen. Even fewer studies have reported combinations of ultrasound and maternal urine markers. While it is clear that consistently high sensitivity and specificity for Down syndrome can be achieved, almost all the studies are based on high-risk groups. Studies in low-risk populations have suffered from lack of standardization. The relevance of genetic sonogram in a low-risk population thus remains to be proven. The most significant challenge, however, remains the development of uniform and reproducible sonographic and measurement standards. This is likely to be the most important factor in optimizing the accuracy of the mid-trimester genetic sonogram.

Genetics of cardiological disorders

Information generated by work on the human genome means that we now understand the genetic basis of many of the cardiac anomalies that present in the fetal and neonatal periods. This allows for an earlier and more definitive diagnosis of an underlying syndrome, although it does not replace the need for an accurate recognition of clinical signs. The implications of this new information are considered in the context of some of the more frequently encountered conditions with cardiac associations.

Down syndrome births in the United States from 1989 to 2001

OBJECTIVE

We investigated the observed and expected Down syndrome livebirths in the US from 1989 to 2001.

STUDY DESIGN

Using birth certificate data, we recorded maternal age-specific live births from 1989 to 2001, and stratified them by women 15 to 34 and 35 to 49 years old. We estimated Down syndrome live births from 1989 to 2001, assuming no terminations. We recorded Down syndrome live births by year from 1989 to 2001.

RESULTS

Despite an expected 1.32-fold increase in Down syndrome live birth rates from 1989 to 2001, Down syndrome live births actually declined. In 1989, the rate of Down syndrome cases was 15% lower than expected, decreasing to 51% by 1998. Women 15 to 34 had 45% fewer affected pregnancies in 2001, while women 35 to 49 had 53% fewer in 2001. We estimated that Down syndrome live births decreased from 3962 in 1989 to 3654 in 2001.

CONCLUSION

Down syndrome live births declined in the US despite an expected increase caused by delayed or extended childbearing.

An isolated echogenic heart focus is not an indication for amniocentesis in 12,672 unselected patients

OBJECTIVE

To evaluate the risk of Down syndrome in fetuses with a heart echogenic focus using the Bayes theorem and likelihood ratios in an unselected population.

METHODS

We prospectively evaluated 12,672 second-trimester sonographic features and extracted and examined a population with an echogenic focus for chromosomal anomalies.

RESULTS

There were 479 cases of echogenic focus; 90.4% were isolated, whereas 9.6% had associated findings. Eleven patients had fetuses with trisomy 21 (9 per 10,000). Eight of those did not have an echogenic focus, whereas 3 had a heart echogenic focus. Only 1 fetus with trisomy 21 had an isolated echogenic focus. The positive likelihood ratio for total cases of a heart echogenic focus and trisomy 21 was 7.25, whereas for an isolated echogenic focus, the positive likelihood ratio was 2.66.

CONCLUSIONS

The results of the statistical analysis showed that the risk of aneuploidy is increased in fetuses with an echogenic intracardiac focus; however, the finding should prompt a detailed structural survey and correlation with a priori risk. Amniocentesis need not be offered to patients who are otherwise at low risk and have an isolated echogenic intracardiac focus.