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

Learning curve for fetal postmortem ultrasound

OBJECTIVE

To determine the learning curve of fetal postmortem ultrasound (PMUS) and evaluate the evolution of its diagnostic performance over the past 8 years.

METHODS

PMUS was performed by two fetal medicine specialists and two experts on 100 unselected fetuses of 12-38 weeks of gestation in a prospective, double-blind manner. 21 pre-defined internal structures were analyzed consecutively by the trainee alone and the expert, with a comparison of diagnosis and immediate feedback. The learning curves for examination duration, non-recognition of structures and final diagnoses were computed using cumulative summation analysis. Secondly, the expert PMUS diagnostic accuracy using autopsy as the gold standard was compared to the previously published data.

RESULTS

The trainees reached expert level of PMUS at 28-36 cases for examination duration (12.1 ± 5.2 min), non-diagnostic rate (6.5%, 137/2100), and abnormality diagnosis. In a group of 33 fetuses ≥20 weeks who had an autopsy, the experts PMUS performance was improved after 8 years with a reduction of all organs non-diagnostic rate (6.5 %VS 11.4%, p < 0.01) and higher sensitivity for the heart (100% VS 40.9%, p < 0.01) and the abdomen (100%VS 56.5%, p < 0.05).

CONCLUSION

PMUS offers a short learning curve for fetal medicine specialists and on-going improvement of diagnostic accuracy over time.

Reference values for ductus venosus Doppler velocity indices between 11 and 13+6 weeks of gestation: A single-center prospective study in Iran

Background

This study aimed to investigate reference Doppler velocimetry indices (DVIs) of the fetal ductus venosus (DV) during 11-13 + 6 gestational weeks.

Materials and Methods

In a prospective observation over referrals to a single tertiary care center in a 2-year interval, normal singleton pregnancies with fetal crown-rump lengths (CRLs) of 43-80 mm were examined by a single experienced sonographer for their DV pulsatility index (DVPI), DV resistance index (DVRI), and S-wave maximum velocity/A-wave minimum velocity (S/A ratio). Multinomial and quantile regression functions were used to analyze the effect of gestational age (estimated by CRL) on reference values (5^th and 95^th percentiles of the distribution in each gestational day/week). P < 0.05 was considered significant.

Results

Over a sample of 415 participants with a mean/median gestational age of 12 + 1 weeks, no significant correlations were found between the CRL and DVIs using multinomial regression functions (linear model best fitted for all [DVPI: B coefficient = 0.001, P = 0.235] [DVRI: B coefficient = 0.001, P = 0.287] [DV S/A: B coefficient = 0.010, P = 283]). Quantile regression analyses of DVIs' reference values were nonsignificant across the CRL range except for the DVRI ([5^th regression line: coefficient = -0.004, P = 0.018] [95^th regression line: coefficient = -0.001, P = 0.030]).

Conclusion

Reference values for DVPI, DVRI, and DV S/A ratios were established as 0.80-1.39, 0.62-0.88, and 2.57-6.70, respectively. Future meta-analyses and multicenter studies are required to incorporate DV DVIs into an updated universal version of the practice.

Performance of Ductus Venosus Doppler (at 11-13 + 6 Weeks) in Predicting Adverse Fetal Outcomes in Indian Population: Going Beyond Aneuploidies: Going Beyond Aneuploidies

OBJECTIVES

The objective of this study is to examine the performance of Ductus venosus (DV) Doppler done at the routine first trimester screening (11-13 + 6 weeks) in predicting the adverse fetal outcomes in Indian population.

METHODS

This observational study was conducted between 2013 and 2019, on 4340 singleton pregnancies. Ductus Doppler were considered abnormal if DV pulsatility index values were >95th centile for that gestation or with a reversed "a" wave. Anatomical survey was done to rule out other abnormalities. Women were followed up till delivery and outcomes were divided into 4 groups: 1) aneuploidies; 2) cardiac defects; 3) non-cardiac structural abnormalities; and 4) miscarriages before 24 weeks or fetal deaths after 24 weeks.

RESULTS

Prevalence of abnormal DV Doppler is 5.12% (205/4004). There were significantly higher number of fetal losses (4.4 versus 0.3%), aneuploidies (10.2 versus 1.7%), fetal cardiac defects (5.9 versus 1.4%), and non-cardiac structural defects (5.4 versus 1.4%) among the pregnancies with abnormal DV Doppler in comparison to those with normal flow (P < .001). Logistic regression analysis has shown that significant contribution to fetal chromosomal abnormalities and cardiac defects was associated with abnormal DV. Other factors which were found to have a significant association with adverse fetal outcome were increased nuchal translucency and increased body mass index (BMI).

CONCLUSION

DV Doppler in first trimester can be used as a screening tool for cardiac defects and fetal deaths. Women with abnormal DV Dopplers should be offered fetal echocardiography at 18-22 weeks and third trimester growth scans with Dopplers.

Antenatal screening for chromosomal abnormalities

Screening for chromosomal disorders, especially for trisomy 21, has undergone a number of changes in the last 50 years. Today, cell-free DNA analysis (cfDNA) is the gold standard in screening for trisomy 21. Despite the advantages that cfDNA offers in screening for common trisomies, it must be recognized that it does not address many other chromosomal disorders and any of the structural fetal anomalies. In the first trimester, the optimal approach is to combine an ultrasound assessment of the fetus, which includes an NT measurement, with cfDNA testing. If fetal structural defects are detected or if the NT thickness is increased, an amniocentesis or a CVS with at least chromosomal microarray should be offered.

Ultrasound Pitfalls in a Complex Fetal Cardiac Malformation—Case Report of a New Arteriovenous Central Communication

Cardiac and cardiovascular malformations are of real interest in terms of definition, epidemiology, and means of early diagnosis by imaging. Although ultrasound examination reaches exceptional performance nowadays, unusual pathologies are still exposed to the risk of either incorrect acquired image or misinterpretation by the specialist in a routine scan. Herein, we present a case of a 20-week-old fetus (from an apparently low-risk pregnancy) with complex cardiac and vascular abnormalities, including an arteriovenous malformation along with ventricular septal defect, ductal coarctation of the aorta, aneurysm of a brachiocephalic vein, and dilation of the entire neck and upper mediastinum venous system, and the limitations that were encountered in the process of diagnosis and management of the case.

Intrapulmonary artery Doppler to predict mortality and morbidity in fetuses with mild or moderate left-sided congenital diaphragmatic hernia

OBJECTIVES

In fetuses with isolated left-sided congenital diaphragmatic hernia (LCDH), prenatal detection of severe pulmonary hypoplasia is important, as fetal therapy can improve survival. Cases with mild or moderate lung hypoplasia still carry a considerable risk of mortality and morbidity, but there has been less interest in the accurate prediction of outcome in these cases. In this study of fetuses with mild or moderate isolated LCDH, we aimed to investigate: (1) the association between intrapulmonary artery (IPA) Doppler findings and mortality at discharge; (2) whether adding IPA Doppler findings improves the prediction of mortality based on lung size and liver herniation; and (3) the association between IPA Doppler findings and early neonatal morbidity.

METHODS

This was a retrospective study of all consecutive fetuses assessed at the BCNatal and UZ Leuven hospitals between 2008 and 2020 with a prenatal diagnosis of isolated, non-severe LCDH, defined as observed-to-expected lung-to-head ratio (o/e-LHR) > 25%, that were managed expectantly during pregnancy followed by standardized neonatal management. An additional inclusion criterion was the availability of IPA Doppler measurements. The primary outcome was the association between IPA Doppler findings and mortality at discharge. Other predictors included o/e-LHR, liver herniation and gestational age at birth. Secondary outcomes were the association between IPA Doppler findings and the presence of pulmonary hypertension (PHT), need for supplemental oxygen at discharge and need for extracorporeal membrane oxygenation. IPA pulsatility index (PI) values were converted into Z-scores. Logistic regression analysis was performed to investigate the associations between predictor variables and outcome, and the best model was chosen based on the Nagelkerke R² .

RESULTS

Observations for 70 non-severe LCDH cases were available. Fifty-four (77%) fetuses survived until discharge. On logistic regression analysis, higher IPA-PI was associated with an increased risk of mortality (odds ratio (OR), 3.96 (95% CI, 1.62-9.70)), independently of o/e-LHR (OR, 0.87 (95% CI, 0.79-0.97)). An IPA-PI Z-score cut-off of 1.8 predicted mortality with a detection rate of 69% and specificity of 93%. Adding IPA-PI to o/e-LHR improved significantly the model's performance (Nagelkerke R² , 46% for o/e-LHR + IPA-PI vs 28% for o/e-LHR (P < 0.002)), with a detection rate of 81% at a 10% false-positive rate. IPA-PI was associated with PHT (OR, 2.20 (95% CI, 1.01-4.59)) and need for oxygen supplementation at discharge (OR, 1.90 (95% CI, 1.10-3.40)), independently of lung size.

CONCLUSIONS

In fetuses with mild or moderate LCDH, IPA-PI was associated with mortality and morbidity, independently of lung size. A model combining o/e-LHR with IPA-PI identified up to four in five cases that eventually died, despite being considered to have non-severe pulmonary hypoplasia. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Diagnosis of major heart defects by routine first-trimester ultrasound examination: association with increased nuchal translucency, tricuspid regurgitation and abnormal flow in ductus venosus

OBJECTIVE

To examine the association between fetal major heart defects and increased nuchal translucency thickness (NT), tricuspid regurgitation and abnormal flow in the ductus venosus in a large population of singleton pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation.

METHODS

This was a retrospective study of prospectively collected data from singleton pregnancies attending for a routine ultrasound scan at 11-13 weeks' gestation, which included examination of fetal anatomy, measurement of NT and assessment of blood flow across the tricuspid valve and in the ductus venosus, according to a standardized protocol. The incidence of fetal NT ≥ 95^th and ≥ 99^th percentiles, tricuspid regurgitation and reversed a-wave in the ductus venosus in fetuses with and those without a major heart defect was determined and the performance of each marker and their combination in the detection of major heart defects was calculated.

RESULTS

The study population of 93 209 pregnancies with no apparent chromosomal abnormality included 211 (0.23%) with a fetal major heart defect and 92 998 morphologically normal neonates. In 113 (53.6%) cases with a major heart defect, the diagnosis was made at the 11-13-week scan, in 82 (38.9%) at the 18-24-week scan, in 10 (4.7%) at the third-trimester scan and in six (2.8%) postnatally. At the 11-13-week scan, we diagnosed all cases of tricuspid or pulmonary atresia and polyvalvular dysplasia, > 90% of cases of hypoplastic left heart syndrome or atrioventricular septal defect, about 60% of complex heart defects and cases of left atrial isomerism (interrupted inferior vena cava with normal intracardiac anatomy), 30-40% of cases of tetralogy of Fallot and arch abnormalities, 25% of tricuspid valve abnormalities and about 15% of cases of transposition of the great arteries, but none of aortic or pulmonary stenosis or common arterial trunk. Fetal NT ≥ 95^th or ≥ 99^th percentile, tricuspid regurgitation or abnormal ductus venosus flow was observed in 77 (36.5%), 45 (21.3%), 61 (28.9%) and 58 (27.5%) fetuses with a major heart defect, respectively, and in 5678 (6.1%), 857 (0.9%), 1136 (1.2%) and 1644 (1.8%) of those without a heart defect. Any one of NT ≥ 95^th percentile, tricuspid regurgitation or abnormal flow in the ductus venosus was found in 117 (55.5%; 95% CI, 48.5-62.3%) fetuses with a heart defect and in 8166 (8.8%; 95% CI, 8.6-9.0%) of those without a heart defect. Any one of NT ≥ 99^th percentile or the other two markers was found in 99 (46.9%; 95% CI, 40.0-53.9%) fetuses with a heart defect and in 3517 (3.8%; 95% CI, 3.7-3.9%) of those without a heart defect.

CONCLUSION

At 11-13 weeks' gestation, measurement of fetal NT and assessment of flow across the tricuspid valve and in the ductus venosus can lead to early diagnosis of major heart defect. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Noninvasive determination of the fetal cardiac interatrial pressure gradients by Doppler ultrasonography: preliminary results

Objective: In 2000, Johnson et al. measured the atrial pressures puncturing the atria invasively in 19 fetuses that will be terminated. In this study, it is aimed to define the fetal cardiac interatrial pressure gradient noninvasively. The pressure gradients were calculated using the ductus venosus (DV) and pulmonary vein (PV) blood flow velocities and Bernoulli equation for flowing fluids.Methods: "S," "a," and the time-averaged maximum velocities in both veins of 246 fetuses were used in the simplified Bernoulli equation; Δp=4 ([Formula: see text]). Additionally, the umbilical vein maximum velocity is measured in order to calculate ducto-umbilical pressure gradient.Results: The average interatrial pressure gradient was biggest in the ventricular systole and the least gradient was in the atrial systole of a cardiac cycle. The pressure gradient changes throughout the second and the third trimester have four periods with two increases and two decreases.Conclusions: The interatrial and ducto-umbilical pressure gradients can be measured noninvasively in order to follow the hemodynamic of the fetal circulatory system.

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.

Does first-trimester nuchal cord affect the blood flow in the ductus venosus? A prospective observational study

INTRODUCTION

Main objective of the present study was to investigate the association between the presence of nuchal cord (NC) and the measurement of the ductus venosus pulsatility index for veins (ductus venosus (DV) PIV).

METHODS

This was a prospective study of 1974 singleton pregnancies that underwent first-trimester screening at 11-13⁺⁶ gestational weeks. Color Doppler was used to demonstrate the presence of a NC in all cases and the DV PIV was calculated routinely, as part of the standard scan. The association between the presence of a NC and the DV PIV was then examined overall and at each gestational week.

RESULTS

A NC was demonstrated in 17.1% of cases. The incidence of nuchal cord was significantly higher at 13-13⁺⁶ weeks (24.7%, n = 119) compared to the one at 12-12⁺⁶ (16.5%, n = 192) and 11-11⁺⁶ weeks (7.9%, n = 26) (p < .001). No significant correlation was found between NC presence and DV PIV (p = .344). The DV PIV was 0.99 (± 0.15) for patients without NC versus 0.99 (± 0.15) for patients with NC (p = .34).

CONCLUSIONS

There was no association between the presence of a NC at 11-13⁺⁶ gestational weeks and the DV PIV.

Neonatal mortality in dogs: Prognostic value of Doppler ductus venosus waveform evaluation - Preliminary results

Aim:

To define the prognostic value of Doppler ultrasonographic morphology of ductus venosus (DV) waveform on canine neonatal mortality.

Materials and Methods:

Fifty-four healthy pregnant bitches underwent fetal ultrasonographic assessment. The DV waveforms were classified as diphasic (dDVw) or triphasic (tDVw) and compared with neonatal mortality.

Results:

Ninety-three fetuses were evaluated. Twenty fetuses belonged to litters with neonatal mortality, in which tDVw was observed. Seven fetuses belonged to litters without neonatal mortality, in which tDVw was observed. Fifty-eight fetuses belonged to litters without neonatal mortality, in which only dDVw was observed. Eight fetuses belonged to litters with neonatal mortality, in which only dDVw was observed. The correlation between tDVw and neonatal mortality was statistically significant (odds ratio [OR], 20.7; p<0.0001). Considering only pregnancies with one or two fetuses with the same DV waveform: Two fetuses with tDVw belonged to litters with neonatal mortality; 1 foetus with tDVw belonged to litter without neonatal mortality and 26 fetuses showed dDVw without neonatal mortality. The correlation between tDVw and neonatal mortality even in litters up to two pups was statistically significant (OR, 88.3; p=0.01).

Conclusion:

Echo-Doppler assessment of DV is feasible in canine fetuses, and the presence tDVw seems to be related to neonatal mortality.

A structurally normal fetus at the 11- to 14-week ultrasound does not guarantee a newborn without congenital anomalies: a cohort study

OBJECTIVE

The objective of this study was to analyze the influence of maternal demographic characteristics and abnormal first-trimester sonographic markers on congenital anomalies (CAs) at birth when the fetus is structurally normal at the 11- to 14-week ultrasound.

METHODS

This prospective cohort study comprised high-risk women undergoing routine antenatal care. Detailed assessments of fetal anatomy and first-trimester sonographic markers were performed at 11-14 weeks of pregnancy. Multilevel regression analysis was used to determine the effects of maternal characteristics and abnormal first-trimester sonographic markers on the incidence of CA at birth.

RESULTS

Three hundred and ten patients were evaluated, and 41 patients (13.2%) had an anomalous newborn. The presence of a specific indication at the first-trimester ultrasound (OR: 2.72; CI 95% 1.09-6.74) or a nuchal translucency (NT) thickness greater than 2.5 mm increased the risk of CA at birth by three fold (OR: 3.10; CI 95% 1.07-9.59). High adjusted risks for trisomies 21, 18 and 13 increased the likelihood of having a structurally abnormal newborn by five, twelve and six fold, respectively.

CONCLUSION

Increased NT and/or high adjusted risks for trisomies 21, 18, and 13 increase the risk of CA at birth, even in fetuses with a structurally normal 11- to 14-week ultrasound scan.

Learning Curve for Intrapulmonary Artery Doppler in Fetuses with Congenital Diaphragmatic Hernia

Objective: To assess the learning curve for intrapulmonary artery Doppler in fetuses with congenital diaphragmatic hernia (CDH). Methods: Three fetal medicine fellows with the theoretic knowledge, but without prior experience, in the evaluation of intrapulmonary artery Doppler in CDH fetuses were selected. Each trainee and 1 experienced explorer assessed the intrapulmonary artery in the contralateral lung to the side of the hernia for calculation of 2 Doppler parameters - pulsatility index (PI) and peak early diastolic reversed flow (PEDRF) - in a cohort of 90 consecutive CDH fetuses. The average difference between the 3 trainees and the expert was calculated. A difference below 15% was considered as accurate measurement. The average learning curve was delineated using the cumulative sum analysis (CUSUM). Results: Among the total 270 intrapulmonary artery Doppler measurements performed by the 3 trainees, the number of failed examinations was 14 (15.6%) and 16 (17.8%) for PI and PEDRF, respectively. The CUSUM plots demonstrate that the learning curve was achieved by 53 and 63 tests performed for calculations of the intrapulmonary artery PI and PEDRF, respectively. Conclusion: Competence in Doppler evaluation of the intrapulmonary artery in CDH fetuses is achieved only after intensive continuous training.

Screening performances of abnormal first-trimester ductus venosus blood flow and increased nuchal translucency thickness in detection of major heart defects

OBJECTIVE

The aim of this study was to evaluate the screening performances of abnormal ductus venosus (DV) blood flow for the detection of heart defects in chromosomally normal fetuses with increased nuchal translucency (NT) thickness at 11-13 + 6 weeks' gestational in a population of singleton pregnancies.

METHODS

During an 8-year period, all singleton pregnancies from 11 + 0 to 13 + 6 weeks were scanned for NT and DV blood flow assessment. Two groups of cases with abnormal NT were evaluated: NT ≥ 95th and NT ≥ 99th centile. DV waveforms were considered to be abnormal if the a-wave was reversed or absent (R/A).

RESULTS

Addition of DV R/A a-wave to either NT ≥ 95th or NT ≥ 99th percentile increased specificity (p < 0.001 and p < 0.001, respectively), but not screening performances in detection of major heart defects (p = 0.73 and p = 0.91, respectively). Combination of DV R/A a-wave with NT ≥ 95th or NT ≥ 99th centile correlated with right heart defects (p = 0.024 and p = 0.013, respectively).

CONCLUSIONS

In chromosomally normal fetuses, addition of abnormal DV a-wave to increased NT does not improve screening performances of NT in detection of major hearts defects in first trimester. However, there is correlation of such parameter with right heart defects and AV septal defects.

How Effective Is First-Trimester Screening for Trisomy 21 Based on Ultrasound Only?

Objective: To evaluate the most common first-trimester ultrasound features of fetuses with trisomy 21 (T21) and to examine the screening performance for Down syndrome (DS) using only ultrasound-based protocols. To investigate whether maternal age (MA) has an impact on the efficacy of the ultrasound-based screening methods. Methods: In a prospective study, 6,265 patients were examined. Two ultrasound-based risk calculation protocols were applied: ‘NT' (based on nuchal translucency) and ‘NT+' (based on NT and secondary markers). Results: A total of 5,696 patients were enrolled for analysis; 84 subjects with T21 were identified. Combinations of abnormal ultrasound markers were observed in only 1.2% of euploid fetuses compared to 71.5% of fetuses with T21. Among 17.9% of DS cases with cardiac anomaly, 14.3% comprised atrioventricular septal defects. For a false-positive rate of 3%, the detection rates of T21 were 73.8 and 91.7% for the ‘NT' and ‘NT+' protocols, respectively. The efficacy of both methods was affected by MA. Conclusions: Most of the fetuses with DS demonstrate a combination of ultrasound markers of aneuploidy in the first trimester. The ‘NT+' protocol is efficient and provides comparable performance as a combined screening test. It is a valuable method, especially when the access to biochemical analysis is restricted.

Factors affecting the feasibility of routine first-trimester fetal echocardiography

OBJECTIVES

The purpose of our study was to assess the factors that may improve the feasibility of routine fetal echocardiography at the time of the first-trimester scan.

METHODS

In this prospective study, we included 616 healthy singleton fetuses. Examinations were performed transabdominally by a single sonographer at the beginning of his training in first-trimester screening. The fetal heart was examined by high-definition color Doppler imaging to obtain the 4-chamber view, right and left ventricular outflow tracts, and 3-vessel and trachea view. Logistic regression was used to investigate the effect on the ability to visualize different cardiac structures.

RESULTS

The frequency of successful heart examinations increased significantly with the number of scans performed (P < .05). The sonographer needed 180 examinations before he could successfully examine the heart in at least 80% of cases. Significant factors that increased the probability of adequate echocardiography were the length of the heart examination and the experience of the sonographer (P< .05) but not transducer-heart distance, maternal body mass index, fetal crown-rump length, placenta interposition, or restrictive fetal position. Visualization of the left ventricular outflow tract could be improved by increasing the experience of the sonographer and decreasing the transducer-heart distance. Also, visualization of the 3-vessel and trachea view depended on the length of the heart examination, the experience of the sonographer, an anterior position of the placenta, and a restrictive fetal position.

CONCLUSIONS

Competence in color flow mapping assessment of the fetal heart at gestational ages of 11 weeks to 13 weeks 6 days is achieved only after extensive supervised training.

Role of ultrasound in the management of diabetes in pregnancy

The purpose of this review is to discuss the established role of ultrasound (US) in the management of pregnancy complicated by diabetes mellitus (DM), as well as new developments with regard to the use of US in this situation. We choose to explore the role of US in pregnancy complicated by DM in three areas: (1) Role of US in estimation of fetal weight. (2) Role of US in diagnosis of congenital malformation. (3) Role of US in monitoring diabetic pregnant patients.

First-trimester contingent screening for trisomy 21 by biomarkers and maternal blood cell-free DNA testing

OBJECTIVE

To define risk cut-offs with corresponding detection rates (DR) and false-positive rates (FPR) in screening for trisomy 21 using maternal age and combinations of first-trimester biomarkers in order to determine which women should undergo contingent maternal blood cell-free (cf) DNA testing.

METHODS

From singleton pregnancies undergoing screening for aneuploidies at three UK hospitals between March 2006 and May 2012, we analyzed prospectively collected data on the following biomarkers: fetal nuchal translucency thickness (NT) and ductus venosus pulsatility index for veins (DV-PIV) at 11 + 0 to 13 + 6 weeks' gestation and serum free β-human chorionic gonadotropin (β-hCG), pregnancy-associated plasma protein-A (PAPP-A), placental growth factor (PlGF) and alpha-fetoprotein (AFP) at 8 + 0 to 13 + 6 weeks. Estimates of risk cut-offs, DRs and FPRs were derived for combinations of biomarkers and these were used to define the best strategy for contingent cfDNA testing.

RESULTS

In contingent screening, detection of 98% of fetuses with trisomy 21 at an overall invasive testing rate < 0.5% can be potentially achieved by offering cfDNA testing to about 36%, 21% and 11% of cases identified by first-line screening using the combined test alone, using the combined test with the addition of serum PlGF and AFP and using the combined test with the addition of PlGF, AFP and DV-PIV, respectively.

CONCLUSIONS

Effective first-trimester screening for trisomy 21, with DR of 98% and invasive testing rate < 0.5%, can be potentially achieved by contingent screening incorporating biomarkers and cfDNA testing.

Analysis of three different strategies in prenatal screening for Down's syndrome in twin pregnancies

OBJECTIVES

To compare the performance of three different strategies in prenatal screening for Down's syndrome in twins [nuchal translucency, the combined test, the combined test + ductus venosus pulsatility index (DVPI)].

METHODS

We included 277 twin pregnancies with two cases of trisomy 21 (both dichorionic). We performed a computer simulation of Down's syndrome NT screening, combined test screening and the combined test with the addition of DVPI screening using the commercialized software SsdwLab6. The strategies were compared using the area under the receiver operating characteristic curve.

RESULTS

NT screening false-positive rate (FPR) was 10.9% (95% CI: 8.3-13.5). The combined test FPR was 6.2% (95% CI: 4.1-8.2%) and the combined test plus DVPI was 6% (95% CI: 4-8). FPR was higher in advanced maternal age patients. Detection rate was 100% in all cases. The area under the curve was 0.987 (95% CI: 0.972-0.994) in NT screening; 0.987 (95% CI: 0.978-0.997) in the combined test and 0.983 (95% CI: 0.977-0.996) in the combined test + DVPI.

CONCLUSIONS

Down's syndrome screening is feasible in twins with low FPR. The results of this study are similar to the results achieved in singletons. The combined test appears to be the most effective. The addition of DVIP does not significantly improve the prenatal screening for trisomy 21.

Cumulative sum plots and retrospective parameters in first-trimester ductus venosus quality assurance

OBJECTIVE

This study aimed to evaluate the application of two quality assurance methods to the ductus venosus pulsatility index (DVPI), as a first-trimester aneuploidy marker, including retrospective assessment of distribution parameters and cumulative sum (CUSUM) plots.

METHODS

The DVPI was measured in 14 444 singleton fetuses at 11+0 to 13+6 weeks in two Fetal Medicine centers during a 4-year period. Sonologist-specific quality assurance distribution parameters, previously described for nuchal translucency, were assessed: the median multiples of the median (MoM), the logarithmic standard deviation of DVPI MoMs and the weekly DVPI percent decrease. Quality assurance results were compared between median MoMs and MoM-based CUSUM plots.

RESULTS

When sonologist-specific DVPI distribution parameters were retrospectively applied for quality assurance, a 1.0 median MoM, a 0.1 median logarithmic standard deviation and a 3.4 median weekly DVPI drop percentage were observed. CUSUM plots showed good agreement with 0.9-1.1 MoMs range for median MoM, in the assessment of sonologist-specific performances.

CONCLUSION

Retrospective and prospective DVPI quality assurance methods appear to be applicable to DVPI at 11+0 to 13+6 weeks. Its use should be encouraged if DVPI is to be added to first-trimester Down syndrome or cardiac defects screening.

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.

Doppler assessment of the fetus with intrauterine growth restriction

OBJECTIVE

We sought to provide evidence-based guidelines for utilization of Doppler studies for fetuses with intrauterine growth restriction (IUGR).

METHODS

Relevant documents were identified using PubMed (US National Library of Medicine, 1983 through 2011) publications, written in English, which describe the peripartum outcomes of IUGR according to Doppler assessment of umbilical arterial, middle cerebral artery, and ductus venosus. Additionally, the Cochrane Library, organizational guidelines, and studies identified through review of the above were utilized to identify relevant articles. Consistent with US Preventive Task Force suggestions, references were evaluated for quality based on the highest level of evidence, and recommendations were graded.

RESULTS AND RECOMMENDATIONS

Summary of randomized and quasirandomized studies indicates that, among high-risk pregnancies with suspected IUGR, the use of umbilical arterial Doppler assessment significantly decreases the likelihood of labor induction, cesarean delivery, and perinatal deaths (1.2% vs 1.7%; relative risk, 0.71; 95% confidence interval, 0.52-0.98). Antepartum surveillance with Doppler of the umbilical artery should be started when the fetus is viable and IUGR is suspected. Although Doppler studies of the ductus venous, middle cerebral artery, and other vessels have some prognostic value for IUGR fetuses, currently there is a lack of randomized trials showing benefit. Thus, Doppler studies of vessels other than the umbilical artery, as part of assessment of fetal well-being in pregnancies complicated by IUGR, should be reserved for research protocols.

Ductus venosus flow at 11-13 weeks in the prediction of birth weight discordance in monochorionic twins

OBJECTIVE

To examine if assessment of ductus venosus (DV) flow, crown-rump length (CRL) and nuchal translucency (NT) thickness can predict the discordance in birth weight in monochorionic (MC) twin pregnancies resulting in two live births.

METHODS

In this prospective study, we assessed CRL, NT and DV flow at 11(+0)-13(+6) weeks' gestation in 326 MC twin pregnancies. The study population included 237 pregnancies without major abnormalities or prenatal interventions resulting in two live births. We examined the value of DV flow and discordance in NT and CRL in the prediction of discordance in birth weight.

RESULTS

In the 237 MC twin pregnancies the median discordance in birth weight was 8.0% (range 0-42.2%). There was no significant association between discordance in either CRL or NT and discordance in birth weight (P=0.116 and P=0.332). In pregnancies with abnormal DV flow in at least one of the fetuses the median discordance in birth weight was higher than in those with normal DV flow in both twins (13.2% vs. 7.8%, P=0.006).

CONCLUSIONS

In uncomplicated MC twin pregnancies, abnormal DV flow in at least one of the fetuses is associated with a higher discordance in birth weight than in those with normal flow in both fetuses.

Quality control for intravascular intrauterine transfusion using cumulative sum (CUSUM) analysis for the monitoring of individual performance

INTRODUCTION

Intravascular intrauterine transfusion (IUT) is an effective and relatively safe method for the treatment of fetal anemia. Although implemented in centers all over the world in the 1980s, the length and strength of the learning curve for this procedure has never been studied. Cumulative sum (CUSUM) analysis has been increasingly used as a graphical and statistical tool for quality control and learning curve assessment in clinical medicine. We aimed to test the feasibility of CUSUM analysis for quality control in fetal therapy by using this method to monitor individual performance of IUT in the learning phase and over the long term.

METHODS

IUTs performed in the Dutch referral center for fetal therapy from 1987 to 2009 were retrospectively classified as successful or failed. Failed was defined as no net transfusion or the occurrence of life-threatening procedure-related complications. The CUSUM statistical method was used to estimate individual learning curves and to monitor long-term performance. Four operators who each performed at least 200 procedures were included.

RESULTS

Individual CUSUM graphs were easily assessed. Both operators pioneering IUT in the late 1980s had long learning phases. The 2 operators learning IUT in later years in an experienced team performed acceptably from the start and reached a level of competence after 34 and 49 procedures.

DISCUSSION

CUSUM analysis is a feasible method for quality control in fetal therapy. In an experienced setting, individual competence may be reached after 30 to 50 IUTs. Our data suggest that operators need at least 10 procedures per year to keep a level of competence.

Learning curve for Doppler measurement of fetal modified myocardial performance index

OBJECTIVE

To assess the learning curve for measurement of the fetal modified myocardial performance index (MPI).

METHODS

Three trainees with the theoretical knowledge of but without prior experience in performing MPI measurement were selected. Each trainee and one experienced examiner measured MPI in a cohort of 90 consecutive fetuses. The average difference between the three trainees and the expert in the MPI measurements was calculated; a difference below 10% was considered to indicate an accurate measurement. Individual and averaged learning curves were delineated using cumulative sum analysis (CUSUM).

RESULTS

The gestational age at evaluation ranged from 20 + 4 to 41 + 4 (mean, 33 + 3) weeks. The CUSUM plots demonstrated that, on average, competence in performing fetal MPI measurement was achieved by 65 cases. The average number of attempts to achieve competence were 42, 77 and 83 for the ejection time, isovolumetric contraction time and isovolumetric relaxation time, respectively.

CONCLUSIONS

Evaluation of fetal MPI by an inexperienced trainee requires on average 65 measurements to achieve competence.

Ductus Venosus: A Love Story of 14 Years

Ductus venosus is a tiny vessel with a central role in fetal circulation. Combining B-mode with color and pulsed Doppler is feasible to identify this vessel and evaluate the blood flow waveform at 11 to 13 weeks. The higher prevalence of abnormal A-wave in fetuses with abnormal karyotype and/or cardiac defects turned DV evaluation into a useful marker for chromosomal abnormalities and cardiopathies. Even when combined with nuchal translucency (NT) or biochemical markers, DV blood flow evaluation contributes to an increase in sensitivity and reduces false-positive rate. Abnormal ductal flow is also related to a worse fetal and perinatal outcome. In monochorionic twin pregnancies, in addition to NT measurement at 11 to 14 weeks, the Doppler assessment of DV blood flow increases relevantly the performance of screening for those at higher risk of developing twin-to-twin transfusion syndrome. This story of 14 years surely contributed to change the way first trimester screening is being implemented.

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.

Two-stage first-trimester screening for trisomy 21 by ultrasound assessment and biochemical testing

OBJECTIVES

This study was carried out to examine the performance of a contingent policy in first-trimester screening for trisomy 21, in which the estimated risk was first derived by a combination of maternal age, fetal nuchal translucency (NT) thickness, presence/absence of the nasal bone, blood flow in the ductus venosus or flow across the tricuspid valve, and biochemical testing was carried out only in those who were found to have an intermediate risk. We also examined the performance of a policy in which the estimated risk was first derived by a combination of maternal age and biochemical testing, and ultrasound examination was carried out only in those with an intermediate risk.

METHODS

The data for this study were derived from prospective screening for trisomy 21 in singleton pregnancies, using, as markers, a combination of maternal age, fetal NT thickness and maternal-serum free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A), in a one-stop clinic for first-trimester assessment of risk at 11 + 0 to 13 + 6 weeks of gestation. Assessment of the fetal nasal bone, ductus venosus flow and tricuspid flow were also routinely performed by appropriately trained sonographers. The performance of different screening policies was examined.

RESULTS

The study population consisted of 19 614 pregnancies with a normal karyotype or delivery of a phenotypically normal baby (euploid group) and 122 cases of trisomy 21. The best performance was achieved by a contingent policy in which first-stage screening was based on maternal age, fetal NT thickness and either tricuspid valve or ductus venosus blood flow, followed by biochemical testing only those with an intermediate risk, of 1 in 51 to 1 in 1000 (which constituted about 20% of the total). The performance of contingent screening in which first-stage testing relies on biochemistry was poorer than when first-stage screening was performed by ultrasound examination because, in order to achieve the same detection rate, the false-positive rate was twice as high.

CONCLUSION

Effective first-trimester screening for trisomy 21 can be achieved by a contingent policy in which first-stage testing is based on ultrasound examination and second-stage biochemical testing is carried out in only 20% of the patients.

Learning curve for lung area to head circumference ratio measurement in fetuses with congenital diaphragmatic hernia

OBJECTIVE

To assess the learning curve for the fetal lung area to head circumference ratio (LHR) calculation in fetuses with congenital diaphragmatic hernia (CDH).

METHODS

Three trainees with the theoretical knowledge, but without prior experience in the LHR measurement, were selected. Each trainee and one experienced examiner measured the observed to expected (O/E)-LHR in the lung contralateral to the side of the hernia by two methods-manual tracing of lung borders and multiplication of the longest diameters-in a cohort of 95 consecutive CDH fetuses. The average difference between the three trainees and the expert in the O/E-LHR measurement was calculated. A difference below 10% was considered to indicate an accurate measurement. The average learning curve was delineated using cumulative sum analysis (CUSUM).

RESULTS

The CUSUM plots demonstrate that the learning curve was achieved by 77 and 72 tests performed for the area obtained by the manual-tracing and multiplication-of-the-longest-diameter methods, respectively.

CONCLUSION

The minimum number of scans required for an inexperienced trainee to become competent in examining the LHR is on average 70.

Learning curve in measurement of fetal frontomaxillary facial angle at 11-13 weeks of gestation

OBJECTIVE

To determine the number of ultrasound examinations required to train sonographers to accurately measure the fetal frontomaxillary facial (FMF) angle at 11-13 weeks of gestation.

METHODS

Eight sonographers accredited for nuchal translucency thickness (NT) measurement (and with different levels of experience) were trained to measure the fetal FMF angle using specially acquired three-dimensional (3D) volumes. Training was provided in cycles, and each cycle consisted of a training period on 20 randomly selected cases followed by an examination using 10 randomly selected cases. During training, the sonographer was informed of the true FMF angle value after each FMF angle measurement on a case-by-case basis. During examination, the difference between the measured and the true values of the FMF angle (i.e. the delta angle) was calculated. A measurement was considered accurate if the delta angle was less than 5 degrees . The sonographer was considered to be competent and the training finished if all 10 examination cases satisfied this criterion. Otherwise, the sonographer would undergo further cycles of training-examination, until he/she became competent.

RESULTS

The number of training cases required for a sonographer to become competent was 40 for two sonographers, 60 for one, 80 for one, 100 for two, 120 for one and 140 for one, with a median of 90. The median number of failed cases reduced from 2.5 (out of 10) at the first cycle to 0 by the 7(th) cycle. As training cycles increased, the mean angle deviation and measurement time required both reduced significantly. The average delta angle of the passing examination cycle was 2.06 +/- 1.40 degrees . The number of training cases required to become competent in FMF angle measurement was 40 for the two most experienced trainees and 80, 120 and 140 for the three least experienced ones.

CONCLUSIONS

We have demonstrated that competence in FMF angle measurement was achieved after a median number of 90 cases, with a range of up to 140. The number required was substantially lower, at 40 cases, among those with extensive experience of NT measurement.

Abnormal first-trimester ductus venosus blood flow: a marker of cardiac defects in fetuses with normal karyotype and nuchal translucency

OBJECTIVE

To evaluate the independent contribution of ductus venosus (DV) blood flow assessment at 11-14 weeks' gestation to the prediction of congenital heart defects (CHD) in chromosomally normal fetuses, irrespective of the value of the nuchal translucency thickness (NT).

METHODS

During a 4-year period, all singleton pregnancies from 11 + 0 to 13 + 6 weeks' gestation were scanned for NT and DV blood flow in a tertiary center. Abnormal DV blood flow was defined as either absent or reversed flow during atrial contraction (AR-DV). Fetal echocardiography was performed in all cases with either NT > 99(th) percentile or AR-DV. Follow-up was assessed by postnatal examination or autopsy in cases of termination of pregnancy or perinatal death.

RESULTS

A total of 6120 pregnancies were scanned at a median gestational age of 12 weeks, and 45 cases of CHD were detected. AR-DV was found in 206 fetuses, of which 145 (70.4%) had a normal karyotype. Among fetuses with AR-DV and normal karyotype, 11 cases of CHD were diagnosed, giving a sensitivity of 24.4%, a positive predictive value of 7.6% and an odds ratio of 9.8. Increased NT (> 99(th) centile) was present in 55 of the 145 (37.9%) cases with AR-DV and normal karyotype, and in 6/11 (54.5%) of those with CHD. Thus, the group of 90 fetuses with abnormal DV blood flow and normal NT contained five cases of CHD, for a sensitivity of 11.1%, a positive predictive value of 5.5% and an odds ratio of 8.5. Right-heart anomalies were predominant in those cases with isolated AR-DV (4/5), but no specific CHD pattern was found in those with increased NT. The detection rate of CHD by the combined use of increased NT and/or AR-DV in the first trimester improved from 28.9% (13/45) to 40.0% (18/45).

CONCLUSIONS

In experienced hands, abnormal DV blood flow in the first trimester is an independent predictor of CHD and should constitute an indication for early echocardiography. In this study, the use of DV blood flow assessment increased early detection of CHD by 11% with respect to the use of NT measurement alone.