The role of ductus venosus blood flow assessment in screening for chromosomal abnormalities at 10-16 weeks of gestation

Clinical Significance of Ductus Venosus Waveform as Generated by Pressure- volume Changes in the Fetal Heart

The ductus venosus is a vascular shunt situated within the fetal liver parenchyma, connecting the umbilical vein to the inferior vena cava. This vessel acts as a bypass of the liver microcirculation and plays a critical role in the fetal circulation. The ductus venosus allows oxygenated and nutrient-rich venous blood to flow from the placenta to the myocardium and brain. Increased impedance to flow in the fetal ductus venosus is associated with fetal aneuploidies, cardiac defects and other adverse pregnancy outcomes. This review serves to improve our understanding of the mechanisms that regulate the blood flow redistribution between the fetal liver circulation and fetal heart and the clinical significance of the ductus venosus waveform as generated by pressure-volume changes in the fetal heart.

Employ ductus venous blood flow in the early detection of trisomy 21, trisomy 18, and trisomy 13: A meta-analysis

BACKGROUND AND OBJECTIVE

Ductus venosus (DV) Doppler has been suggested as a biomarker for the early screening of trisomy diseases. However, results from different studies have been largely inconsistent. This study aimed to investigate the relationship between DV and top 3 fetal aneuploidies by a systematical meta-analysis: trisomy 21 (T21), trisomy 18 (T18), and trisomy 13 (T13).

METHODS

We performed a literature search covering articles from Medline, PubMed, RePORTER, and Elsevier publications. DV-T21/T18/T13 relation data were extracted from 9, 7, and 6 previous studies, respectively, including 31,053, 28,092 and 26,721 pregnant women worldwide. Both random-effects and fixed-effect model were used to study the log odds ratio (LOR) of T21, T18, and T13 in case of DV. Four potential influential factors were studied using a multiple linear regression (MLR) model, including maternal age, data age, sample size, and population region.

RESULTS

DV was significantly related to T21, T18, and T13 (LOR = 3.44, 3.89 and 3.46; P value <2.1E-13). Significant between-study variance was observed for T21 (P value <1.71E-14), but not for T18 (P value >.05) and T13 (P value >.87). MLR results suggested that significant influential factors could include population region (P value <.0021), but not sample size, data age, and maternal age (P value >.078).

CONCLUSIONS

Integrating DV could help in the detection of trisomy. However, accuracy and validity may vary depending on the population regions, which need further study.

Early diagnosis of trisomy 21, trisomy 18 and trisomy 13 using nuchal translucency thickness and ductus venosus blood flow waveform in West China

Abnormal nuchal translucency (NT) thickness and ductus venosus (DV) blood flow have been associated with trisomy 21, 18 and 13. However, the association of abnormal DV with these aneuploidies varies among clinical studies. The present study examined the possibility of using NT combined with DV for the early diagnosis of the three aforementioned aneuploidies in the Western Chinese population, focusing on three aspects: Biological pathway analysis, theoretical statistical analysis and clinical data analysis from 1,962 first‑trimester pregnant women from Western China. The pathway and statistical analyses performed suggested the reliability of integrating NT and DV in the prediction of the three aneuploidies. The clinical data analysis suggested that integrating NT and DV, compared with NT alone, resulted in increased predictive power (34.09 vs. 22.45%), better rejection probability (0.21 vs. 0.44%), increased specificity (96.71 vs. 94.07%) and increased sensitivity (89.47 vs. 80.49%). The present results suggested the reliability of integrating NT and DV for the early diagnosis of trisomy 21, 18 and 13 for the Western Chinese population. The present results provided novel statistical analyses to the field of prenatal diagnosis in the Western Chinese population.

Ductus venosus blood flow velocity waveforms during the early second trimester of pregnancy in a Thai population

OBJECTIVE

To establish reference ranges for ductus venosus (DV) blood flow velocities and indices during the early second trimester.

METHODS

A cross-sectional DV Doppler study of fetuses at 15-22 weeks of gestation was conducted at Songklanagarind Hospital, Songkhla, Thailand, during 2013-2014. The peak forward velocities were recorded and the DV indices were calculated. Predicted reference ranges based on the 5th and 95th percentiles according to the week of gestation were constructed.

RESULTS

Among 371 fetuses, measurement of DV Doppler waveforms in the sagittal plane was achieved in 97.5% of cases. With advancing pregnancy (weeks 15 to 22), the DV velocities during ventricular systole, early diastole, and atrial contraction increased from 47.48 cm/s to 68.22 cm/s, 42.23 cm/s to 60.52 cm/s, and 15.94 cm/s to 34.84 cm/s, respectively. The time-averaged maximum value increased from 37.61 cm/s to 55.42 cm/s. The DV indices-pulsatility index for the vein, peak velocity index for the vein, preload index, and systolic/a-wave ratio-decreased from 0.79 to 0.59, 0.71 to 0.53, 0.63 to 0.47, and 2.72 to 1.90, respectively. The systolic/diastolic ratio remained relatively constant at 1.12.

CONCLUSIONS

Normal reference ranges for DV flow velocities and indices during the early second trimester were established.

Effects of fetal cardiac anomalies on ductus venosus and aortic isthmus doppler profiles

PURPOSE

To demonstrate the blood flow profiles of fetuses with cardiac anomalies at the level of Ductus venosus (DV) and Aortic isthmus (AI) to evaluate the effects of fetal cardiac anomalies on these profiles, and how these profile changes contribute to cardiac anomaly screening studies as a marker.

METHODS

DV and AI doppler studies were applied to 64 singleton pregnant women with fetal cardiac anomalies and 74 pregnant women with healthy fetuses. DV-PVIV (peak velocity index for veins) for DV and IFI (isthmic flow index) for AI were used.

RESULTS

DV doppler studies in fetuses with cardiac anomalies and healthy fetuses did not show statistically significant difference. But the results of the AI doppler studies had statistically significant difference in the fetal cardiac anomaly group with the exception of cases with dilatation and regurgitation. When right-sided heart anomaly and the remaining cases were compared with the control groups, AI doppler results also showed lower IFI values.

CONCLUSIONS

DV doppler studies in the second or third trimester may not be suitable as a screening test for congenital heart disease, but AI doppler studies might be considered as a supporting parameter. But further studies are needed for routine clinical use.

Further insights into diastolic dysfunction in first-trimester trisomy-21 fetuses

OBJECTIVE

To assess fetal cardiac function in first-trimester trisomy-21 fetuses as compared with fetuses with other aneuploidies, euploid fetuses with cardiac defects or isolated increased nuchal translucency (NT) and controls.

METHODS

During a 2.5-year period, NT, ductus venosus (DV) blood flow, diastolic filling time, early filling time, tricuspid flow, tricuspid and mitral valve E/A velocity ratios, left ventricle shortening fraction, left myocardial performance index and fetal heart rate were assessed in fetuses with a crown-rump length between 45 and 84 mm undergoing chorionic villus sampling at our center. Cardiac parameters among study groups were compared with the use of 95% CIs.

RESULTS

The study population comprised 28 fetuses with trisomy 21, 25 with other aneuploidies, 94 euploid fetuses with abnormal findings (27 with cardiac defects, 31 with other structural anomalies and 36 with isolated increased NT) and 271 controls. Trisomy-21 fetuses showed signs of diastolic dysfunction such as increased DV pulsatility index and E/A ratios together with a higher prevalence of tricuspid regurgitation. However, no differences were found in euploid fetuses with cardiac defects or isolated increased NT.

CONCLUSIONS

No signs of cardiac dysfunction were observed in euploid fetuses with increased NT or cardiac defects, while in trisomy-21 fetuses signs of diastolic dysfunction could be potentially attributed to volume overload.

Screening performance for trisomy 21 comparing first trimester combined screening and a first trimester contingent screening protocol including ductus venosus and tricuspid flow

OBJECTIVE

To compare the standard first trimester combined risk assessment for trisomy 21 with a contingent screening protocol including tricuspid flow and ductus venosus flow.

MATERIAL AND METHOD

Women with singleton pregnancies and a first trimester combined risk assessment>1:1000 were included. They all had additional assessment of the ductus venosus and the tricuspid flow. We compared screening performance in two screening strategies: (a) First trimester combined screening strategy based on the individual risk results from the routine screening test and (b) Contingent screening strategy based on a combination of the routine test results and additional ultrasound markers.

RESULTS

We included 917 women in the study, 894 in the euploid group and 23 in the trisomy 21 group. Using a contingent screening strategy resulted in a significant decrease in screen positive rate from 48.3% to 17.7% (p<0.001) in the studied population. There was no statistical difference in detection rate between the two screening strategies.

CONCLUSION

There is increasing evidence in favour of using additional ultrasound markers as part of contingent screening protocols in the first trimester. We do suggest performing further studies in routine clinical settings to provide validation of the available risk algorithms.

Is the addition of the ductus venosus useful when screening for aneuploidy and congenital heart disease in fetuses with normal nuchal translucency?

OBJECTIVE

The aim of this study was to examine the possible role of Doppler ultrasound assessment of ductus venosus (DV) blood flow at 11⁺⁰-13⁺⁶ weeks' gestation in fetuses with normal nuchal translucency (NT) in screening for autosomal trisomies (AT) and for congenital heart diseases (CHD) in chromosomally normal fetuses.

METHODS

First-trimester combined screening for trisomy 21 (T21) was carried out prospectively for 7 years in singleton pregnancies. NT and the pulsatility index for DV (DVPI) were calculated. The DV was analyzed according to its association with AT and CHD. The detection rate (DR), false-positive rate (FPR), positive predictive value (PPV), and odds ratio (OR) for abnormal DV were calculated.

RESULTS

Abnormal DV as an early marker of euploid CHD gives a DR of 12.5%, an FPR of 4.3%, a PPV of 1.4%, and a negative predictive value (NPV) of 99.5%, with an OR of 3.1 (95% CI 1.3-7.4). Moreover, abnormal DV as an early marker of AT shows a DR of 35.7%, an FPR of 4.3%, a PPV of 1.2%, an NPV of 99.9%, and an OR of 12.3 (95% CI 4.1-36), and the values are 33.3, 4.3, 0.97, and 99.9% and 11 (95% CI 3.2-36.9), respectively, for T21.

CONCLUSIONS

Our data supports the association between increased DVPI and CHD or AT. The sensitivity of this marker is not strong enough to be used a screening test.

A preliminary retrospective study about the relationship between ductus venosus Doppler indices, nuchal translucency (NT) and biochemical markers in the first and second trimester screening tests

In our study, we tried to assess the relation between ductus venosus Doppler indices [pulsatility index (PI), resistance index (RI) and S/D] and first-trimester screening markers (MoM of serum pregnancy-associated plasma protein A, pappalysin 1 (PAPP-A), MoM of serum free β-human chorionic gonadotrophin (β-hCG), and nuchal translucency (NT) and second trimester screening markers (MoM of serum α-fetoprotein, MoM of serum total β-hCG and MoM of serum estriol). We analyzed the data of 121 singleton pregnancies. Roche cobas e 601ECLIA (electrochemiluminescence immunoassay) was used to measure MoM of serum PAPP-A and Roche cobas e 602 ECLIA (electrochemiluminescence immunoassay) was used to measure MoM of serum free β-hCG in the first trimester. Beckman Coulter Access 2 Immunoassay was used to measure MoM of serum α-fetoprotein, MoM of serum total β-hCG and MoM of serum estriol in the second trimester. The first author performed all ultrasound screenings and ductus venosus Doppler studies. What we found new in our study is presented as following; MoM of serum α-fetoprotein had a negative correlation with RI of ductus venosus Doppler, MoM of serum estriol had a negative correlation with RI of ductus venosus Doppler and MoM of serum estriol had a negative correlation with S/D of ductus venosus doppler. The results of our study suggest that ductus venosus Doppler can be used to increase the effectiveness of the second trimester screening test.

First-trimester measurement of the ductus venosus pulsatility index and the prediction of congenital heart defects

OBJECTIVE

This study was carried out to evaluate the additional predictive value of ductus venosus pulsatility index for veins (DV-PIV) in the identification of congenital heart defects (CHDs) in fetuses with an enlarged nuchal translucency (NT) and a normal karyotype.

METHODS

All chromosomally normal fetuses referred to our Fetal Medicine Unit between September 1996 and December 2008 with known NT, DV-PIV and ductus venosus (DV) a-wave measurements were included. Intrafetus variation in DV-PIV was overcome by averaging three recordings. Follow-up included special focus on CHD. The odds of CHD at any NT and DV-PIV value were evaluated using logistic regression analysis.

RESULTS

Of 792 fetuses included, the NT was enlarged (equal to or above the 95(th) percentile (P95)) in 318 (40.2%). The DV-PIV was abnormal (≥ P95) in 41.8% of the fetuses with an enlarged NT and the a-wave was abnormal (negative or reversed) in 29.9%. CHD was diagnosed in 35 fetuses, 33 of which had an enlarged NT. Amongst the fetuses with an enlarged NT, the sensitivities for CHD of abnormal DV-PIV and DV a-wave were 73% and 55%, with specificities of 62% and 73%, respectively. Logistic regression analysis showed that in this risk group the DV-PIV multiple of the median (MoM) (as a continuous variable) was significantly associated with the risk of CHD (odds ratio = 2.4), independent of the degree of NT enlargement, whereas the DV a-wave did not significantly add to the prediction of CHD.

CONCLUSION

Two-thirds of fetuses with an enlarged NT, a normal karyotype and CHD have an increased DV-PIV. DV-PIV can be used as continuous variable in combination with NT to increase specificity in the identification of CHD and to refine the individual risk assessment.

The assessment of nuchal translucency and serum markers for down syndrome screening with ductus venosus Doppler measurements in the first trimester

OBJECTIVE

The aim of the study was to improve nuchal translucency (NT) and serum marker Down syndrome (Tri21) screening methods by including fetal ductus venosus (DV) Doppler measurements.

MATERIAL AND METHODS

A total of 213 pregnant women were screened consecutively by combining maternal age, fetal NT and maternal serum pregnancy associated plasma protein A (PAPP-A) and free β-human chorionic gonadotropin (f β-HCG) values at 11-14 weeks of gestation. Also, a DV Doppler analysis was performed for the contribution to the screening for Tri21 and other fetal anomalies or adverse pregnancy outcomes.

RESULTS

Twelve fetuses had DV PI measurements above the 95th percentile and two (17%) developed intrauterine growth retardation. DV PI values negatively correlated with birth weight (p=0.013, r=0.171). Two patients had T 21 among the study group (0.9%) with abnormal biochemical screening results. In these with Tri21, the combined test risk was above the suggested limit (>1/250). PAPP-A was <0.4 MoM in 23, and f β-HCG was >1.91 MoM in 49 patients. The rates of false positivity were 10% for PAPP-A and 22% for f β-HCG. The sensitivity, specificity, positive and negative predictive values of the combined test was 100%, 95%, 20% and 100%, respectively.

CONCLUSION

The combined test has high sensitivity and specificity for Tri21 detection. The addition of DV Doppler ultrasound in the first trimester might have the advantage of predicting some adverse pregnancy outcomes. However, in the Turkish population, further studies with larger numbers of patients will be needed to establish the usefulness of DV for the detection of Tri21 or the prediction of some major cardiac anomalies.

Ductus venosus pulsatility index measurement reduces the false-positive rate in first-trimester screening

OBJECTIVE

To investigate if ductus venosus (DV) pulsatility index for veins (PIV) and a-wave measurements can increase the accuracy of first-trimester Down syndrome screening in a high-risk population.

METHODS

The database of our fetal medicine unit was searched for all cases at increased first-trimester Down syndrome risk. Multivariable logistic regression was used to construct a prediction rule for chromosomal anomalies at any given maternal age, nuchal translucency multiples of the median (NT-MoM) and DV-PIV MoM. The discriminative ability of the model was assessed by using receiver-operating characteristics (ROC) analysis.

RESULTS

The study population included 445 fetuses. DV-PIV was increased (≥ 95(th) percentile) in 239 (54%) and DV a-wave was abnormal in 187 fetuses (42%). In this cohort, 80% of all chromosomal anomalies were identified by an increased DV-PIV and 68% by an abnormal a-wave. The odds of chromosomal anomalies increased by a factor of 4.2 per MoM increase in DV-PIV, adjusted for NT and maternal age. The area under the ROC curve for the prediction of chromosomal anomalies was 0.79. After correction for DV-PIV, DV a-wave did not significantly add to the prediction of chromosomal anomalies.

CONCLUSION

In a population of fetuses at increased first-trimester risk for Down syndrome, the combination in a logistic regression model of NT, DV-PIV and maternal age can improve the accuracy of screening for trisomy 21 and other chromosomal anomalies. This is the first study that models the additional value of DV-PIV as a continuous variable to NT measurement alone in a high-risk first-trimester population.

Additional first-trimester ultrasound markers

The first trimester (11-13 +6 weeks) ultrasound examination is useful for several reasons: determination of an accurate date of confinement, diagnostic purposes, and screening for fetal defects. Nuchal translucency measurement combined with maternal serum markers (free b-human chorionic gonadotropin and pregnancy-associated plasma protein A) is the mainstay of first-trimester screening for chromosomal defects. However, over the past decade additional ultrasound markers have been developed that improve the performance of this type of screening. The novel markers include evaluation of the nasal bone, fronto-maxillary angle measurement, and Doppler evaluations of the blood flow across the tricuspid valve and in the ductus venosus.

Prenatal sonographic features of fetuses in trisomy 13 pregnancies. IV

Prenatal ultrasound is a powerful tool to detect structural abnormalities associated with the fetuses in trisomy 13 pregnancies. This article provides a comprehensive review of the prenatal sonographic markers of trisomy 13 in the first trimester, including fetal nuchal translucency thickness, fetal heart rate, fetal nasal bone, fetal tricuspid regurgitation, ductus venous flow, fetal crown-rump length, fetal trunk and head volume, fetal frontomaxillary facial angle, gestational sac volume and umbilical cord diameter, along with biochemical markers such as maternal serum free beta-human chorionic gonadotropin, maternal serum pregnancy-associated plasma protein-A, maternal serum placental growth factor, and the fetal and total cell-free DNA concentration in the maternal circulation.

First Trimester Ultrasound Screening: An Update

For many years, the main use of ultrasound in the first trimester of pregnancy was to confirm viability and to establish gestational age. Indeed, the crown-rump length measurement in the first trimester remains the most accurate method to estimate the gestational age even today. However, improvements in ultrasound equipment and improvement in our understanding of normal and abnormal fetal development allows us now to perform a much more complete first trimester fetal evaluation. This pertains not only to the diagnosis of fetal anomalies but also to screening for fetal defects. The combination of the nuchal translucency measurement and maternal serum biochemistries (free β-hCG and PAPP-A) has been shown to be an extremely efficient way to screen for fetal aneuploidy. The addition of other first trimester markers such as the nasal bone evaluation, frontomaxillary facial angle measurement, and Doppler evaluation of blood flow across the tricuspid valve and through the ductus venosus improves the screening performance even further by increasing the detection rates and decreasing the false positive rates. Several of the first trimester markers also are useful in screening for cardiac defects. Furthermore, significant nuchal translucency thickening has been associated with a variety of genetic and nongenetic syndromes. A recently described first trimester marker called the intracerebral translucency appears to hold great promise in screening for open spine defects. Finally, it appears that a first trimester evaluation (uterine artery Doppler and the measurement of certain biochemical markers in the maternal serum) significantly improves the assessment of the risk of preeclampsia.

Ductus venosus pulsatility index as an antenatal screening marker for Down's syndrome: use with the Combined and Integrated tests

OBJECTIVES

To assess the value of ductus venosus blood flow (expressed as pulsatility index, DVPI) in antenatal Down's syndrome screening when used with the Combined and Integrated tests.

METHODS

DVPI measurements between 10 and 13 weeks' gestation in 66 Down's syndrome and 7184 unaffected pregnancies were collected from women attending the Hospital Clinic, Barcelona, for antenatal care from 1999 to 2007 and combined with the Serum Urine and Ultrasound Screening Study (SURUSS) data to model screening performance, safety and cost-effectiveness of the screening tests with and without DVPI.

RESULTS

The median DVPI multiple of the normal median in Down's syndrome pregnancies was 1.55 (95% CI 1.36-1.73). As a single screening marker without using maternal age, DVPI has a 62% detection rate for a 5% false-positive rate. At a 90% detection rate (first trimester measurements at 11 weeks' gestation) the addition of DVPI reduced the false-positive rate of the Combined test from 8.5% to 4.6% and the Integrated test from 2.0% to 1.1%, with a corresponding reduction in fetal losses from diagnostic procedures. There was no material loss of cost-effectiveness.

CONCLUSION

Addition of DVPI measurements to the Combined and Integrated tests substantially improves the efficacy and safety of antenatal Down's syndrome screening.

The nuchal translucency and the fetal heart: a literature review

In this overview the current knowledge of the relationship between an increased nuchal translucency (NT) measurement and fetal heart structure and function in chromosomally normal fetuses is reviewed. Relevant pathophysiological theories behind the increased NT are discussed. Fetuses with an increased NT have an increased risk for congenital heart disease (CHD) with no particular bias for one form of CHD over another. This risk increases with increasing NT measurement. Although the NT measurement is only a modestly effective screening tool for all CHD when used alone, it may indeed be effective in identifying specific CHD "likely to benefit" from prenatal diagnosis. The combination of an increased NT, tricuspid regurgitation and an abnormal ductus venosus (DV) Doppler flow profile, is a strong marker for CHD. A fetal echocardiogram should be performed at 20 weeks' gestation in fetuses with an NT > or = 95th percentile but < 99th percentile. When the NT measurement is > or = 99th percentile, or when tricuspid regurgitation and/or an abnormal DV flow pattern is found along with the increased NT, an earlier echocardiogram is indicated, followed by a repeat scan at around 20 weeks' gestation. The resultant increased demand for early fetal echocardiography and sonographers with this special expertise needs to be planned and provided for.

Male gender as a favorable prognostic factor in pregnancies with enlarged nuchal translucency

OBJECTIVE

The aim of this study was to investigate the influence of fetal gender on pregnancy outcome in fetuses with enlarged nuchal translucency (NT).

METHODS

Pregnancy outcomes of all women who underwent an NT measurement at our institution between January 2000 and November 2007 were retrospectively reviewed. Separate analyses were performed for fetuses with normal and with enlarged (>or= 95(th) percentile) NT.

RESULTS

A normal NT was measured in 3637 males (51.4%) and 3435 females (48.6%). Of the fetuses with enlarged NT 365 were males (57.4%) and 271 females (42.6%) (P = 0.001). In this group a normal pregnancy outcome-of those pregnancies for which the outcome was known-was registered for 187/332 (56.3%) of the male fetuses and 98/249 (39.4%) of the female fetuses (P < 0.001; relative risk (RR) for adverse outcome for male gender, 0.72). Eighty percent of the chromosomally normal male fetuses with an enlarged NT had an uneventful pregnancy outcome; this increased to 90% when only the male fetuses with NT measurements >or= 95(th) percentile and < 99(th) percentile and normal karyotype were considered (RR for adverse outcome for male gender, 0.47).

CONCLUSION

In a population of fetuses with enlarged NT there are significantly more males. Male fetuses with enlarged NT and normal chromosomes have an almost two-fold greater chance of a favorable outcome than females. We believe that a minimal degree of NT enlargement in male fetuses without genetic or structural anomalies may be interpreted as a feature of accelerated growth or, alternatively, as a maturational delay of the cardiovascular system more common in males, leading to moderately increased nuchal fluid accumulation.

Ductus venosus Doppler in screening for trisomies 21, 18 and 13 and Turner syndrome at 11-13 weeks of gestation

OBJECTIVES

To investigate the performance of first-trimester screening for aneuploidies by including assessment of ductus venosus flow in the combined test of maternal age, fetal nuchal translucency thickness, fetal heart rate, and serum free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A.

METHODS

Screening by the combined test was performed in singleton pregnancies, including 19 614 with euploid fetuses, 122 with trisomy 21, 36 with trisomy 18, 20 with trisomy 13 and eight with Turner syndrome. In all cases the a-wave in the fetal ductus venosus flow was assessed. We examined the performance of two screening strategies: first, assessment of the a-wave in all patients and, second, first-stage screening using the combined test in all patients followed by second-stage assessment of the a-wave only in those with an intermediate risk of one in 51 to one in 1000 after the first stage

RESULTS

Reversed a-wave was observed in 3.2% of the euploid fetuses, and in 66.4%, 58.3%, 55.0% and 75.0% of fetuses with trisomies 21, 18 and 13 and Turner syndrome, respectively. Inclusion of ductus venosus flow in all pregnancies would detect 96%, 92%, 100% and 100% of trisomies 21, 18 and 13 and Turner syndrome, respectively, at a false-positive rate of 3%. The same detection rates were achieved with the two-stage strategy at a false-positive rate of 2.6%, in which it was necessary to assess the ductus venosus in only 15% of the total population.

CONCLUSIONS

Assessment of ductus venosus flow improves the performance of first-trimester screening for aneuploidies.

First-trimester ultrasound: current uses and applications

This article is aimed to aid the sonographer and medical care provider in better interpretation and clinical application of first-trimester ultrasound findings in early pregnancy. We review current uses, applications, and interpretations of first-trimester ultrasound. A discussion of basic embryology and normal as well as abnormal first-trimester sonographic findings are discussed. We also cover the utility of the first-trimester ultrasound in screening for fetal aneuploidy. Attention is also given to the role of the first-trimester ultrasound in the prediction of adverse perinatal and maternal outcomes.

Learning curve for Doppler assessment of ductus venosus flow at 11 + 0 to 13 + 6 weeks' gestation

OBJECTIVE

To determine the number of scans necessary for training sonographers to examine accurately the ductus venosus at 11 + 0 to 13 + 6 weeks' gestation.

METHODS

Ten sonographers with prior extensive experience in the measurement of nuchal translucency thickness were given practical training in the accurate assessment of the ductus venosus. They were then asked to examine the ductus venosus during the routine 11 + 0 to 13 + 6 weeks' scan. Each scan was assessed by an experienced sonographer and classified as being successful or unsuccessful (failure to obtain a waveform, poor quality image with contamination or wrong classification of the A-wave). Each sonographer performed a total of 300 examinations, the data were analyzed in 15 groups of 20 examinations and in each group the percentage of unsuccessful examinations was calculated.

RESULTS

In the total 3000 cases examined by the 10 sonographers there were 2849 (95.0%) successful examinations and 151 unsuccessful, including 104 failures to obtain a waveform, 30 cases where the quality of the image was considered to be inadequate and 17 cases in which the classification of the A-wave was wrong. The overall frequency of unsuccessful examinations decreased significantly with the number of scans carried out (r = 0.982, P < 0.0001). The sonographers required an average of 80 examinations before they could successfully examine the ductus in at least 19 of a group of 20 scans. Although one of the 10 trainees achieved this standard within the first block of 20 scans some of the sonographers required training in 100 cases.

CONCLUSION

Competence in Doppler assessment of the ductus venosus is achieved only after extensive supervised training.

Estudo da translucência nucal, ducto venoso, osso nasal e idade materna na detecção de cromossomopatia fetal em uma população de alto risco

OBJETIVO: Avaliar a translucência nucal, o ducto venoso, o osso nasal e a idade materna > 35 anos como testes de rastreamento para aneuploidias entre 12 e 14 semanas de gestação em pacientes de alto risco. MATERIAIS E MÉTODOS: Estudo prospectivo observacional envolvendo 92 gestantes entre 12 e 14 semanas submetidas a biópsia de vilo corial por alto risco de trissomia, baseado na medida da translucência nucal (17,4%) e idade materna >35 anos (78,3%). Antes da biópsia de vilo corial, realizaram-se medida da translucência nucal, avaliação de fluxo no ducto venoso e identificação do osso nasal. Calcularam-se a sensibilidade, a especificidade, o valor preditivo positivo e o valor preditivo negativo para testes realizados em paralelo e em seqüência. RESULTADOS: Encontrou-se alteração cromossômica em 12 (13,5%) fetos; 7 (58,3%) apresentavam trissomia 21. Osso nasal foi identificado em todos os fetos com trissomia. Translucência nucal, ducto venoso e idade materna isolados mostraram baixa sensibilidade (41,67-58,33%) e baixo valor preditivo positivo (10-45,45%). A associação translucência nucal + ducto venoso + idade materna apresentou o melhor resultado (sensibilidade: 100%; especificidade: 6,49%; valor preditivo positivo: 14,29%; valor preditivo negayivo: 100%). CONCLUSÃO: Em gestantes com idade > 35 anos, a associação translucência nucal + ducto venoso mostra-se como a mais sensível para a indicação de procedimento invasivo.

The use of nuchal translucency in contemporary obstetric practice

Nuchal translucency sonography is the most powerful single prenatal marker for Down syndrome. Its detection rate is 75% at a 5% false-positive rate. The combination of nuchal translucency and maternal serum-free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A can identify 85% to 90% of fetuses with Down syndrome for a false-positive rate of 5%. This method can also identify more than 90% of fetuses with trisomies 18 and 13, Turner syndrome, and triploidy for a screen-positive rate of 1%.

[Screening of chromosomal abnormalities--the focus is on the first trimester]

<zakljucak> U savremenoj perinatologiji skriningu hromozomopatija posvecuje se velika paznja i postojece metode se stalno unapredjuju. Bez obzira koji test koristili, treba biti samokritican - ultrazvucni pregled u prvom trimestru je veoma vazan ne samo zbog markera hromozomopatija, nego i iskljucivanja postojanja velikih defekata fetusa, te je potrebno napraviti detaljan pregled. Merenje nuhalne translucencije je jedan od najvaznijih koraka ovog procesa, i preporucuje se da svi operateri koji pristupaju proceni rizika od hromozomopatija prodju adekvatnu obuku i sertifikaciju Fondacije za fetalnu medicinu, radi postizanja adekvatnog nivoa pregleda i reproducibilnosti rezultata. Laboratorije koje se bave biohemijskim skriningom i u prvom i u drugom trimestru moraju biti sertifikovane za to, te imati stalnu spoljnu kontrolu kvaliteta rezultata, jer je u protivnom vise kako lazno pozitivnih, tako i lazno negativnih nalaza, sto smanjuje stopu detekcije. Veoma je vazno da se pacijentima uvek napomene i to da se radi o procesu skrininga, ma koliko efikasan on bio, a ne definitivne dijagnoze i da se dijagnoza moze postaviti samo na osnovu invazivne intervencije i odredjivanja kariotipa ploda. .

Abnormal first-trimester ductus venosus blood flow: a risk factor for adverse outcome in fetuses with normal nuchal translucency

OBJECTIVES

First-trimester nuchal translucency thickness (NT) is a potent tool for assessment of fetal risks of aneuploidy and other adverse outcomes. When NT is increased, Doppler assessment of the ductus venosus (DV) enhances the prediction specificity for Down syndrome. This study assessed abnormal Doppler DV waveform as a predictor of adverse outcome when the NT is normal.

METHODS

This was a case-control study of 2,505 consecutive patients undergoing NT screening in our certified first-trimester screening program. First-trimester Doppler assessment of DV was performed and atrial systolic velocity was rated as antegrade (normal) or absent/reversed (DV-RAV; abnormal). Each case with normal NT (< 95(th) percentile) and DV-RAV was matched with two controls with respect to maternal age within 1 year, NT within 0.2 mm, crown-rump length within 3 mm, and closest calculated aneuploidy risk. Outcomes for paired variables were compared using t-test and Chi-square test.

RESULTS

Forty-seven (1.9%) patients had normal NT and DV-RAV. After exclusion of three cases with obvious first-trimester anomalies and two with incomplete outcome data, 42 remained for analysis. Adverse outcome included cardiovascular defects (n = 6), fetal growth restriction (n = 3), renal anomaly (n = 2), aneuploidy (n = 3) and multiple defects (n = 3), in a total of 11/42 cases (26.2%). Cardiac abnormalities, renal abnormalities and perinatal death were all significantly more common in the study group (all P < 0.05).

CONCLUSIONS

Abnormal first-trimester DV Doppler findings appear to predict adverse outcome independently of a normal NT. These patients need detailed mid-trimester assessment of fetal anatomy with formal echocardiography, and subsequent follow-up.

Nuchal Translucency and First Trimester Risk Assessment

First-trimester risk assessment for fetal aneuploidy using nuchal translucency (NT) measurement is rapidly gaining popularity in the United States. In combination with maternal serum markers in the first trimester, the screening performance is exceptionally good, with detection rates of more than 80% at a screen positive rate of 5%. Recently, the method has been validated for screening for Down syndrome and other aneuploidies in multicenter trials in the United States and elsewhere. Compliance with established criteria for measurement of the NT is essential to achieve uniform reliability and high screening test sensitivity. There is an international consensus about the importance of specific training in the NT examination, conformity to standards of NT measurement, and regular audit for quality assurance. In the United States, the Nuchal Translucency Quality Review program has been developed to administer credentialing and quality review for registered practitioners. The Nuchal Translucency Quality Review credentials signify the proficiency of the sonographer or sonologist in NT measurement and participation in a regular quality assurance audit. We encourage accreditation of clinical sites offering first-trimester risk assessment to ensure the highest quality care.

First trimester ultrasonography in screening and detection of fetal anomalies

An obstetrical ultrasound examination provides invaluable information regarding the fetus. Until the mid-1980s, ultrasound in the first trimester was limited to localization of the pregnancy, establishing viability, and accurate dating. With the advent of high-resolution ultrasound and transvaginal scanning, a significant amount of information about the fetus can be gained and provided to the patient at a very early stage in gestation. This article provides an overview of the role of first trimester (11-13 + 6 weeks' gestation) ultrasound in screening and diagnosis of fetal anomalies. The first trimester is an ideal time for screening for aneuploidy, primarily due to the advantages that nuchal translucency (NT) measurement provides. NT measurement is also useful in establishing the risk of congenital cardiac disorders and a number of genetic and non-genetic syndromes. Significant NT thickening is associated with an increase in perinatal morbidity and mortality. Potential mechanisms resulting in increased NT are discussed. A number of new ultrasound markers for fetal aneuploidy have been investigated over the past several years, some of which appear to improve the screening efficacy of early ultrasonography. The role of these is reviewed. A number of fetal anomalies can now be consistently diagnosed in the first trimester. Their appearance at this early gestational age is discussed as well. It is clear that, data obtained by first trimester ultrasound are useful in counseling expectant parents and in planning the appropriate follow-up.

First-trimester ductus venosus, nasal bones, and Down syndrome in a high-risk population

OBJECTIVE

Assessing the role of fetal ductus venosus and nasal bones evaluation in first-trimester screening for Down syndrome.

METHODS

This was a prospective cohort study in a tertiary referral fetal medicine unit involving 628 consecutive fetuses undergoing chorionic villus sampling. The indication for chorionic villus sampling was an increased risk (more than 1:300) for trisomy 21 based on maternal age and nuchal translucency screening in 313 cases (54.7%), increased maternal age in 195 (34.1%), and other in 64 (11.2%). Immediately before chorionic villus sampling, an ultrasound examination was performed. The pattern of blood flow in the ductus venosus and the presence or absence of the nasal bones was noted.

RESULTS

A satisfactory examination of both ductus venosus and nasal bones was possible in 572 fetuses. Of these, 497 (86.9%) had a normal karyotype, and 47 (8.2%) were affected with Down syndrome. The likelihood ratio for trisomy 21 was 7.05 (95% confidence interval 4.27-11.64) in the case of abnormal ductus venosus flow and 6.42 (95% confidence interval 3.86-10.67) in the case of absent nasal bones.

CONCLUSION

In addition to increased fetal nuchal translucency, Down syndrome is significantly associated with first-trimester abnormal flow velocity patterns in the ductus venosus and hypoplasia of the nasal bones.

Human fetal cardiac function during the first trimester of pregnancy

OBJECTIVE

To investigate first trimester human fetal cardiac function in relation to cardiac volume blood flow, and peripheral arterial and venous blood flow patterns.

METHODS

Transvaginal Doppler ultrasonography was performed in 16 uncomplicated pregnancies at 6+, 7+, 8+, 9+, and 10+ gestational weeks. The shape of the inflow waveform and the presence of atrioventricular valve regurgitation (AVVR) were noted. The outflow mean velocity (Vmean) was calculated. The proportions of the isovolumetric relaxation (IRT%) and contraction times (ICT%) of the cardiac cycle were defined. Ductus venosus and umbilical artery pulsatility indices (PI) were obtained.

RESULTS

Every inflow waveform was monophasic before 9+ weeks. At 9+ weeks 11 of 16 and at 10+ weeks all waveforms were biphasic. At 7+ and 8+ weeks AVVR was documented in one case. At 9+ and 10+ weeks AVVR was present in four and seven fetuses, respectively. Mean (SD) outflow Vmean increased between 6+ and 8+ weeks from 3.6 (1.5) to 8.4 (3.0) cm/s (p < 0.05). IRT% decreased significantly from 6+ to 7+ weeks (39.8 (2.6) to 19.2 (6.2), p < 0.001). ICT% decreased between 8+ and 9+ weeks from 13.2 (4.0) to 8.5 (2.5) (p < 0.05). Ductus venosus PIs were unchanged. Umbilical artery Vmean increased between 7+ and 10+ weeks from 1.59 (0.51) to 5.06 (1.06) cm/s (p < 0.001) and PIs remained unchanged.

CONCLUSIONS

The first trimester of pregnancy is characterised by significant improvements in cardiac diastolic and systolic function with a concomitant increase in cardiac volume blood flow. At 10+ weeks AVVR is a common finding. Placental volume blood flow increases significantly with no change in the placental vascular impedance.

First-trimester fetuses with increased nuchal translucency do not show altered intracardiac flow velocities

OBJECTIVE

To study intracardiac flow velocities in first-trimester fetuses with normal nuchal translucency thickness (NT) and those with increased NT.

METHODS

Ultrasound examinations were performed in 85 normal fetuses and 45 fetuses with NT > 95(th) percentile. Follow-up was complete and postmortem examination was performed on terminated pregnancies. Flow velocities during the early (e-wave) and late (a-wave) peaks across the tricuspid and mitral valves were measured and compared, using multilevel analysis, between the fetuses with normal and those with increased NT. In the group with increased NT, fetuses with and without a heart defect irrespective of the karyotype were compared, and in this group, euploid and aneuploid fetuses were compared, irrespective of the presence of a heart defect.

RESULTS

No difference in intracardiac flow velocities was found between fetuses with normal and those with increased NT. Within the group of fetuses with increased NT, there was no difference between the fetuses with and without a cardiac defect. However, comparison of aneuploid with euploid fetuses within the group with increased NT showed that both the e-wave and a-wave peaks were decreased significantly by 3.03 cm/s and 5.95 cm/s, respectively, across the tricuspid valve, and by 3.47 cm/s and 5.92 cm/s, respectively, across the mitral valve (P < 0.05). The most common cardiac malformations were septal defects.

CONCLUSION

There is no difference in intracardiac blood flow velocities between normal fetuses and those with increased NT. This contradicts the theory that NT is caused by impaired atrial contraction or cardiac failure. In fetuses with increased NT, those with aneuploidy show a decreased e-wave and a-wave compared with euploid fetuses. This cannot, however, be explained by the presence of cardiac defects, because there is no difference between fetuses with and without a cardiac defect. Therefore, we hypothesize that the relationship between enlarged NT and cardiac defects can only be explained by a developmental process that coexists at this period of gestation and is linked to cardiovascular development.

Multicenter study of first-trimester screening for trisomy 21 in 75 821 pregnancies: results and estimation of the potential impact of individual risk-orientated two-stage first-trimester screening

OBJECTIVES

To evaluate the performance of first-trimester screening for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A). In addition, the potential impact of a new individual risk-orientated two-stage approach to first-trimester screening was examined.

METHODS

First-trimester combined screening for trisomy 21 was carried out in 75 821 singleton pregnancies with live fetuses at 11 + 0 to 13 + 6 gestational weeks. The detection and false-positive rates for different risk cut-offs were calculated. To examine the potential impact of an individual risk-orientated two-stage approach to first-trimester screening it was assumed that, after first-trimester combined screening, chorionic villus sampling (CVS) would be performed in all patients with a risk estimate of 1 in 100 or more and in none of those with a risk estimate of less than 1 in 1000. Those in the intermediate-risk category, with a risk estimate of between 1 in 101 and 1 in 1000, would have further assessment of risk by first-trimester ultrasound examination to determine presence/absence of the nasal bone, presence/absence of tricuspid regurgitation or normal/abnormal Doppler velocity waveform in the ductus venosus, and CVS would be performed if their adjusted risk became 1 in 100 or more.

RESULTS

Fetal NT and maternal serum free beta-hCG and PAPP-A were successfully measured in all cases. The median maternal age was 31 (range, 13-49) years, the median gestation at screening was 12 (range, 11 + 0 to 13 + 6) weeks and the median fetal crown-rump length was 62 (range, 45-84) mm. Chromosomal abnormalities were identified in 544 pregnancies, including 325 cases of trisomy 21. The estimated risk for trisomy 21 was 1 in 300 or greater in 5.2% of normal pregnancies, in 92.6% of those with trisomy 21, in 88.5% of those with trisomy 18 or 13 and in 85.6% of those with other chromosomal defects. The detection rates for trisomy 21 were about 75% and 80% for respective false-positive rates of 1% and 2%. In the proposed individual risk-orientated two-stage screening for a risk cut-off of 1 in 100 the total false-positive rate would vary with the method used for the second stage of screening from 2.1% for absence of the nasal bone to 2.7% for increased impedance in the ductus venosus and 2.7% for tricuspid regurgitation and the respective detection rates would be 92.0%, 94.2% and 91.7%.

CONCLUSIONS

First-trimester combined screening for trisomy 21 is associated with a detection rate of about 90% for a false-positive rate of 5%. Individual risk-orientated two-stage screening for trisomy 21 can potentially identify, in the first trimester of pregnancy, more than 90% of affected fetuses for a false-positive rate of 2-3%.

Middle cerebral artery peak systolic and ductus venosus velocity waveforms in the hydropic fetus

OBJECTIVE

The purpose of this study was to assess whether Doppler assessment of the middle cerebral artery (MCA) peak systolic velocity (PSV) and ductus venosus (DV) velocity waveforms during sonography of hydropic fetuses may specify the cause of fetal hydrops.

METHODS

A level II sonographic examination was performed in 16 hydropic fetuses, and the MCA PSV and DV velocity waveforms were assessed. The MCA PSV values divided hydropic fetuses into anemic (group 1) and nonanemic (group 2) fetuses. In group 2 fetuses, the DV was defined as normal or abnormal. Sonographic examination and Doppler assessment of these vessels specified the cause of hydrops and indicated the use of specific investigations for diagnosing the etiology of fetal hydrops.

RESULTS

Seven of 16 fetuses had MCA PSV values greater than 1.50 multiples of the median (group 1). Nine of 16 fetuses had normal MCA PSV values (group 2); among them, 7 of 9 had either absent or reversed flow in the DV, and 2 had a normal DV. In group 1, the cause of fetal anemia was investigated by maternal serum tests, and 5 cordocentesis procedures were performed. In group 2, 7 of 9 fetuses had reversed flow in the DV, which suggested a cardiac abnormality confirmed by echocardiography. Five cordocentesis procedures were performed for fetal karyotype, and in 2 fetuses, the cause of hydrops was idiopathic.

CONCLUSIONS

Our data suggest that assessment of the MCA PSV and DV velocity waveforms in the hydropic fetus may further our knowledge of the etiology of hydrops and may indicate which investigations among the many available should be used for diagnosing the cause of fetal hydrops.

First-trimester screening for Down syndrome with ductus venosus Doppler studies in addition to nuchal translucency and serum markers

OBJECTIVE

To estimate the improvement in screening efficiency when fetal ductus venosus Doppler studies are added to existing first-trimester Down syndrome screening protocols.

METHODS

Statistical modelling was used with parameters derived from prospective ductus venosus studies and from the published literature. The pulsatility index for veins (PIV), was determined in the fetal ductus venosus for 3706 unaffected and 25 Down syndrome pregnancies at 10-14 weeks' gestation. Concurrent nuchal translucency measurement and maternal serum pregnancy associated plasma protein A and free-beta human chorionic gonadotrophin were also measured.

RESULTS

The median PIV in Down syndrome was 1.70 times higher than in unaffected pregnancies (95% confidence interval 1.36-2.12). PIV levels followed an approximately log Gaussian distribution with log(10) standard deviations of 0.193 and 0.076 in Down syndrome and unaffected pregnancies. There were no statistically significant correlations between PIV and the other markers. Modelling predicts that for a fixed 5% false-positive rate, the addition of PIV to nuchal translucency alone will increase the detection rate from 76 to 85%, and combined with serum markers, from 88 to 92%. For a fixed 85% detection rate, the false-positive rate reduced from 15 to 4.8% and from 3.2 to 1.2% respectively.

CONCLUSION

Ductus venosus Doppler studies can substantially improve Down syndrome screening efficiency.

First-trimester screening for aneuploidy

Prenatal screening for aneuploidy in the first trimester using novel ultrasound and maternal serum markers represents a promising improvement over the currently available second-trimester screening methods. This article reviews the current status of first-trimester screening for Down syndrome and other aneuploidies and explores the issues related to implementing first-trimester screening into mainstream prenatal care in the United States.

Doppler assessment of cardiac function at 11-14 weeks' gestation in fetuses with normal and increased nuchal translucency

OBJECTIVE

To investigate cardiac dysfunction as a potential underlying mechanism for increased nuchal translucency (NT) in fetuses with chromosomal abnormality or heart defects.

METHODS

Myocardial performance index (MPI) and atrioventricular valve E/A ratios for both sides of the heart were measured by Doppler echocardiography in fetuses at 11-14 weeks' gestation. The study groups consisted of 159 normal control fetuses, 199 otherwise normal fetuses but with increased NT > or = 4 mm, 142 fetuses with trisomy 21, 58 with trisomy 18, 19 with trisomy 13, 37 with Turner's syndrome and 24 with isolated heart defects. Groups were compared using Student's t-test and confidence intervals for differences between groups were calculated.

RESULTS

Otherwise normal fetuses with increased NT showed no difference in any of the cardiac Doppler parameters from normal controls. Mean E/A ratio was slightly but significantly increased in trisomy 21 fetuses compared with normal controls (0.604 vs. 0.578 on the right, P = 0.011; 0.581 vs. 0.542 on the left, P = 0.0001). E/A ratio was not significantly different between any of the other groups and the normals but there was a small increase in absolute E-wave velocity in trisomy 18 fetuses. MPI was significantly decreased in trisomy 21 fetuses, (0.330 vs. 0.378, P = 0.002 on the left) and also in Turner's syndrome fetuses (0.301 vs. 0.352 on the right, P = 0.04; 0.320 vs. 0.378 on the left, P = 0.034) implying better performance, but not in the other groups.

CONCLUSIONS

The magnitude and/or direction of the differences shown do not support a major role for cardiac functional abnormality in the development of NT. Important cardiac dysfunction could not be demonstrated in association with increased NT in normal or abnormal fetuses.

Ductus venosus blood flow assessment at 11 to 14 weeks of gestation and fetal outcome

OBJECTIVE

To evaluate the association between abnormal ductus venosus (DV) at 11-14 weeks' gestation and chromosomal abnormalities, structural defects and fetal outcome.

METHODS

DV flow-velocity waveform (DV-FVW) and nuchal translucency thickness (NT) were prospectively evaluated in 1217 singleton pregnancies.

RESULTS

The DV-FVW was abnormal in 84 fetuses, NT was above the 95th centile in 160 fetuses and both markers were observed in 41 fetuses. Chromosomal defects were diagnosed in 22 fetuses. The sensitivity, specificity and positive and negative predictive values for an abnormal karyotype were 86.4%, 86.9%, 11.9% and 99.7%, respectively, for an increased NT. These values were 68.2%, 96.9%, 31.3% and 99.3%, respectively, for DV-FVW abnormalities and 68.2%, 97.6%, 36.6% and 99.3%, respectively, when both markers were found simultaneously. Regarding structural defects, these values were 43.8%, 92.9%, 8.3% and 99.1% for an abnormal NT, 25.0%, 92.6%, 4.8% and 98.8% for DV-FVW abnormalities and 25.0%, 97.9%, 15.4% and 98.9% for both together. Considering those cases of unexplained fetal demise, the values were 44.4%, 85.9%, 5.0% and 98.9% for NT abnormalities, 22.2%, 92.6%, 4.8% and 98.6% for an abnormal DV-FVW and 22.2%, 98%, 15.4% and 98.7% for both. In cases with increased NT, the percentage of live births with normal karyotype and no major fetal structural defects decreased from 93.8% in normal DV-FVW fetuses to 77.3% in abnormal ones.

CONCLUSION

DV assessment at 11-14 weeks' gestation is useful in screening for fetal chromosomal abnormalities and may help to reduce the false-positive rate when combined with NT measurement. Abnormal DV-FVW is also associated with an increase in adverse perinatal outcome in fetuses with enlarged NT. However, the value of DV-FVW assessment in cases with normal NT is unclear.

Ductus venosus assessment at the time of nuchal translucency measurement in the detection of fetal aneuploidy

OBJECTIVE

To assess the potential value of ductus venosus Doppler studies in the detection of fetal aneuploidy on measurement of nuchal translucency.

METHODS

The pulsatility index for veins (PIV) and the lowest velocity during atrial contraction (A-wave) were determined in the fetal ductus venosus in 3382 consecutive pregnancies at 10 to 14 weeks and studied from December 1996 to December 2001. Nuchal translucency was also measured. The population studied included 1664 pregnancies at high risk and 1718 at low risk for fetal aneuploidy.

RESULTS

In relation to the prenatal detection of trisomy 21, the ductus venosus PIV was increased in 75% (36/48), the A-wave was decreased in 58% (28/48), and nuchal translucency was enlarged in 81% (39/48) of the trisomy 21 fetuses [71% (22/31) when nuchal translucency referrals were excluded]. The corresponding figures for trisomies 18 and 13 were 71, 58 and 83%, respectively, being 33, 33 and 33% for other unbalanced anomalies.

CONCLUSION

There is a high proportion of fetuses with trisomies 21, 18 and 13 (around 75%) in which the ductus venosus PIV is increased (above the 95th percentile) at 10 to 14 weeks, this proportion being similar to that observed for increased nuchal translucency measurement.

Jugular vein and carotid artery blood flow in fetuses with increased nuchal translucency at 10-14 weeks' gestation

OBJECTIVE

The aim of our study was to obtain measurements of the jugular vein and carotid artery pulsatility index (PI) at 10-14 weeks' gestation in chromosomally normal and abnormal fetuses with or without increased nuchal translucency (NT), in order to explore whether a relationship exists between increased NT and overperfusion of the head.

METHODS

This was a prospective study involving 179 pregnant women at high risk for chromosomal anomalies or structural malformations who were referred for chorionic villus sampling or first-trimester ultrasound examination at 10-14 weeks' gestation, respectively. Color and pulsed Doppler ultrasound were used to obtain jugular vein and carotid artery blood flow velocity waveforms at the level of the mid-neck. All Doppler measurements were obtained by a single investigator. The PIs of the jugular vein and carotid artery were correlated with NT measurement and fetal karyotype.

RESULTS

Doppler measurements of the jugular vein and carotid artery were successfully obtained in 90.5% of the fetuses. The fetal karyotype was abnormal in 13 cases, including three trisomies 21 and two trisomies 18, and normal in 149 cases. In the group with normal karyotype the NT was above the 95th percentile in 22 cases (15%). No correlation between the jugular vein or the carotid artery PI and the thickness of the NT was found. There were no significant differences when comparing the values of the jugular vein and carotid artery PI between the group with normal NT and the group with increased NT, or between the group with a normal karyotype and an abnormal karyotype.

CONCLUSION

Our results suggest that NT is not related to blood flow impedance in either the carotid artery or the jugular vein. Overperfusion and venous congestion of the head do not appear to be a causative pathophysiological mechanism involved in increased NT.

Abnormal cardiac function in fetuses with increased nuchal translucency

OBJECTIVE

To evaluate cardiac function in structurally and chromosomally normal fetuses with increased nuchal translucency (NT).

METHODS

Forty-two structurally and chromosomally normal fetuses with increased NT at 11-14 weeks of gestation underwent fetal echocardiographic examination at 20-23 weeks. Fifty fetuses with normal NT values were considered as controls. Pulmonary and aortic peak velocity and time to peak velocities were measured as indices of ventricular systolic function. The ratios between the E-wave and A-wave (E/A) and the ratios between the E-wave and time velocity integral (E/TVI) at the level of both atrioventricular valves were evaluated as indices of ventricular diastolic function.

RESULTS

In fetuses with increased NT the E/A ratios were significantly decreased when compared to control fetuses at the level of both the mitral (0.52 +/- 0.09 vs. 0.60 +/- 0.10, P = 0.0002) and tricuspid (0.51 +/- 0.09 vs. 0.61 +/- 0.09, P < 0.0001) valves. Similar results were found for the E/TVI ratios (mitral valve 4.79 +/- 1.03 vs. 5.63 +/- 1.23, P = 0.0007 and tricuspid valve 4.40 +/- 0.88 vs. 5.19 +/- 0.82, P < 0.0001). No significant relationship was found between the degree of NT and the abnormalities in Doppler indices. There were no significant differences in Doppler systolic indices.

CONCLUSION

Structurally and chromosomally normal fetuses with increased NT have low E/A and E/TVI ratios at 20-23 weeks of gestation. These findings might indicate cardiac diastolic dysfunction.

Prenatal diagnosis of hypoplastic left heart syndrome and trisomy 18 in a fetus with normal nuchal translucency and abnormal ductus venosus blood flow at 13 weeks of gestation

We describe a case of early prenatal diagnosis of a major congenital heart anomaly and trisomy 18 in a low-risk pregnant woman. Nuchal translucency (NT) measurement at 13 weeks' gestation was 1.2 mm and Doppler evaluation of the ductus venosus detected a persistent reversed flow during atrial contraction. This finding prompted us to perform fetal echocardiography which showed hypoplastic left heart syndrome. Karyotyping following chorionic villus sampling diagnosed trisomy 18. Review of the recent literature suggests that the finding of an abnormal ductus venosus Doppler pattern in the late first trimester of pregnancy may be an early sign of either congenital cardiac or chromosomal abnormality, even in the presence of normal NT screening.