Celocentesis for early prenatal diagnosis of hemoglobinopathy

OBJECTIVE

Celocentesis is an invasive technique that can provide prenatal diagnosis of single-gene disorders, from as early as 7 weeks' gestation. The objective of this study was to examine the safety of celocentesis.

METHODS

In this prospective study, celocentesis was performed for prenatal diagnosis of hemoglobinopathy in 402 singleton pregnancies in which both parents were carriers of β-thalassemia or sickle cell disease trait. We assessed procedure-related maternal discomfort or pain, success of sampling and obtaining results, pregnancy outcome and postnatal follow-up.

RESULTS

First, celocentesis was carried out at a median gestational age of 8.6 (range, 6.9-9.9) weeks and celomic fluid was successfully aspirated in 99.8% of cases. Second, 67% of women had no or only mild discomfort, 18% had moderate discomfort, 12% had mild-to-moderate pain and 3% had severe pain. Third, prenatal diagnosis from analysis of the celomic fluid was successful in 93.8% cases, and in the last 121 cases, it was always successful. Fourth, in all cases of successful sampling and analysis of celomic fluid, the diagnosis was concordant with results obtained from additional prenatal or postnatal testing. Fifth, in addition to diagnosis of hemoglobinopathy, quantitative fluorescence polymerase chain reaction analysis, which was performed to evaluate maternal contamination using several markers for chromosomes X, Y, 21, 18 and 13, led to the accurate diagnosis of chromosomal aneuploidy. Sixth, in all cases of an affected fetus diagnosed by celocentesis in which the parents chose termination of pregnancy, this was carried out < 10 weeks' gestation. Seventh, in 97.1% (298/307) of the continuing pregnancies there was live birth, in seven (2.3%) there was miscarriage and in two (0.7%) there was loss to follow-up. Eighth, fetal abnormalities were diagnosed in three (1%) cases, including unilateral transverse amputation of the forearm, unilateral moderate hydronephrosis and small-bowel duplication. All neonates were examined by a pediatrician and were found to be phenotypically normal, except for the three cases with a prenatally diagnosed defect.

CONCLUSIONS

Celocentesis can be used for early prenatal diagnosis of genetic abnormalities, and the procedure-related risk of pregnancy complications appears to be low. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Competing-risks model for prediction of small-for-gestational-age neonate from maternal characteristics and serum pregnancy-associated plasma protein-A at 11-13 weeks' gestation

OBJECTIVES

To develop a continuous likelihood model for pregnancy-associated plasma protein-A (PAPP-A), in the context of a new competing-risks model for prediction of a small-for-gestational-age (SGA) neonate, and to compare the predictive performance of the new model for SGA to that of previous methods.

METHODS

This was a prospective observational study of 60 875 women with singleton pregnancy undergoing routine ultrasound examination at 11 + 0 to 13 + 6 weeks' gestation. The dataset was divided randomly into a training dataset and a test dataset. The training dataset was used for PAPP-A likelihood model development. We used Bayes' theorem to combine the previously developed prior model for the joint Gaussian distribution of gestational age (GA) at delivery and birth-weight Z-score with the PAPP-A likelihood to obtain a posterior distribution. This patient-specific posterior joint Gaussian distribution of GA at delivery and birth-weight Z-score allows risk calculation for SGA defined in terms of different birth-weight percentiles and GA. The new model was validated internally in the test dataset and we compared its predictive performance to that of the risk-scoring system of the UK National Institute for Health and Care Excellence (NICE) and that of logistic regression models for different SGA definitions.

RESULTS

PAPP-A has a continuous association with both birth-weight Z-score and GA at delivery according to a folded-plane regression. The new model, with the addition of PAPP-A, was equal or superior to several logistic regression models. The new model performed well in terms of risk calibration and consistency across different GAs and birth-weight percentiles. In the test dataset, at a false-positive rate of about 30% using the criteria defined by NICE, the new model predicted 62.7%, 66.5%, 68.1% and 75.3% of cases of a SGA neonate with birth weight < 10^th percentile delivered at < 42, < 37, < 34 and < 30 weeks' gestation, respectively, which were significantly higher than the respective values of 46.7%, 55.0%, 55.9% and 52.8% achieved by application of the NICE guidelines.

CONCLUSIONS

Using Bayes' theorem to combine PAPP-A measurement data with maternal characteristics improves the prediction of SGA and performs better than logistic regression or NICE guidelines, in the context of a new competing-risks model for the joint distribution of birth-weight Z-score and GA at delivery. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Screening for pre-eclampsia at 11-13 weeks' gestation: use of pregnancy-associated plasma protein-A, placental growth factor or both

OBJECTIVE

First-trimester screening for pre-eclampsia (PE) is useful because treatment of the high-risk group with aspirin reduces the rate of early PE with delivery at < 34 weeks' gestation by about 80% and that of preterm PE with delivery at < 37 weeks by 60%. In previous studies, we reported that the best way of identifying the high-risk group is by a combination of maternal factors, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF). An alternative biochemical marker is pregnancy-associated plasma protein-A (PAPP-A), which is used widely as part of early screening for trisomy. The objective of this study was to examine the additive value of PlGF and PAPP-A in first-trimester screening for preterm PE by maternal factors, MAP and UtA-PI and define the risk cut-off and screen-positive rate to achieve a desired detection rate of PE if PAPP-A rather than PlGF was to be used for first-trimester screening.

METHODS

This was a non-intervention screening study. The data were derived from prospective screening for adverse obstetric outcomes in women with singleton pregnancy attending for a routine first-trimester hospital visit. Patient-specific risks of delivery with PE at < 37 weeks' gestation were calculated using the competing-risks model to combine the prior distribution of gestational age at delivery with PE, obtained from maternal characteristics and medical history, with multiples of the median (MoM) values of MAP, UtA-PI, PlGF and PAPP-A. The performance of screening in the total population and in subgroups of women of white and black racial origin was estimated. McNemar's test was used to compare the detection rate, for a fixed screen-positive rate, of screening with and without PlGF and PAPP-A. Risk cut-offs and screen-positive rates to achieve desired detection rates of preterm PE were determined in screening with and without PlGF and PAPP-A.

RESULTS

The study population was composed of 60 875 singleton pregnancies, including 1736 (2.9%) that developed PE. There are three main findings of this study. First, the performance of first-trimester screening for PE by a combination of maternal factors, MAP, UtA-PI and PlGF is superior to that of screening by maternal factors, MAP, UtA-PI and PAPP-A; for example, in screening by maternal factors, MAP, UtA-PI and PlGF, at a screen-positive rate of 10%, the detection rate of PE with delivery at < 37 weeks' gestation was 74.1%, which was 7.1% (95% CI, 3.8-10.6%) higher than in screening by maternal factors, MAP, UtA-PI and PAPP-A. Second, addition of serum PAPP-A does not improve the prediction of PE provided by maternal factors, MAP, UtA-PI and PlGF. Third, the risk cut-off and screen-positive rate to achieve a given fixed detection rate of preterm PE vary according to the racial composition of the study population and whether the biomarkers used for screening are MAP, UtA-PI and PlGF or MAP, UtA-PI and PAPP-A. For example, in screening by a combination of maternal factors, MAP, UtA-PI and PlGF in white women, if the desired detection rate of preterm PE was 75%, the risk cut-off should be 1 in 136 and the screen-positive rate would be 14.1%; in black women, to achieve a detection rate of 75%, the risk cut-off should be 1 in 29 and the screen-positive rate would be 12.5%. In screening by a combination of maternal factors, MAP, UtA-PI and PAPP-A in white women, if the desired detection rate of preterm PE was 75%, the risk cut-off should be 1 in 140 and the screen-positive rate would be 16.9%; in black women, to achieve a detection rate of 75%, the risk cut-off should be 1 in 44 and the screen-positive rate would be 19.3%.

CONCLUSION

In first-trimester screening for PE, the preferred biochemical marker is PlGF rather than PAPP-A. However, if PAPP-A was to be used rather than PlGF, the same detection rate can be achieved but at a higher screen-positive rate. © 2020 Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Screening for trisomy at 11-13 weeks' gestation: use of pregnancy-associated plasma protein-A, placental growth factor or both

OBJECTIVE

Serum pregnancy-associated plasma protein-A (PAPP-A) and placental growth factor (PlGF) at 11-13 weeks' gestation are reduced in pregnancies with fetal trisomy and in those that subsequently develop pre-eclampsia (PE). In screening for trisomy, the established biochemical marker is PAPP-A, whereas in screening for PE, the preferred marker is PlGF. The objective of this study was to examine the impact of replacing PAPP-A by PlGF in first-trimester screening for trisomies 21, 18 and 13 by maternal age, fetal nuchal translucency thickness (NT) and free β-human chorionic gonadotropin (β-hCG).

METHODS

This was a prospective screening study in singleton pregnancies for trisomies 21, 18 and 13 by a combination of maternal age, fetal NT and serum PAPP-A and free β-hCG at 11-13 weeks' gestation in which we also measured PlGF. Multiples of the median (MoM) values were calculated for PAPP-A, free β-hCG and PlGF. The dataset was split randomly into training and test datasets of roughly equal size, and the parameters for PlGF obtained from the training dataset were used in risk calculation for the test dataset. Standardized detection rates were computed by obtaining the likelihood ratios for biochemistry and fetal NT for trisomy-21, -18 and -13 pregnancies in the sample and then applying these to each year of maternal age from 12 to 50 to estimate the age-specific detection rates. These were then weighted according to the maternal age distributions of trisomy-21, -18 and -13 pregnancies in England and Wales in 2018. Similarly, standardized false-positive rates (FPR) were computed by obtaining the likelihood ratios for biochemistry and NT, as appropriate, in normal pregnancies in the sample and then applying these to each year of maternal age from 12 to 50 to estimate the age-specific FPRs. A modeling approach was used to assess the performance of screening according to gestational age at biochemical testing.

RESULTS

The study population of 71 266 pregnancies included 70 858 (99.4%) with normal fetal karyotype or birth of a phenotypically normal neonate and 263 with trisomy 21, 109 with trisomy 18 and 36 with trisomy 13. There are five main findings of this study. First, the performance of screening for trisomy by the first-trimester combined test or the combined test in which PAPP-A is replaced by PlGF is substantially better at 11 than at 13 weeks' gestation; for example, the detection rates of trisomy 21 by the combined test were 94%, 90% and 84%, at 5% FPR, when testing was carried out at 11, 12 and 13 weeks, respectively, and the corresponding values in screening by a test in which PAPP-A is replaced by PlGF were 90%, 87% and 86%, respectively. Second, in trisomy-21 pregnancies, the deviation of median PAPP-A MoM from normal decreases with increasing gestational age, whereas the deviation in PlGF does not change with gestational age. Third, the performance of screening for trisomy 21 during the 11^th and 12^th gestational weeks is superior if screening includes PAPP-A rather than PlGF, whereas during the 13^th week the performance is slightly higher with the use of PlGF rather than PAPP-A. Fourth, in our population with mean gestational age at testing of 12.7 weeks, screening by maternal age, fetal NT, serum free β-hCG and serum PAPP-A predicted 88%, 96% and 97% of cases of fetal trisomies 21, 18 and 13, respectively, at a FPR of 5%; the respective values in screening by a test in which PAPP-A is replaced by PlGF were 85%, 96% and 96%. Fifth, addition of serum PlGF does not improve the prediction of trisomy provided by maternal age, fetal NT and serum free β-hCG and PAPP-A.

CONCLUSION

In first-trimester screening for trisomy, the preferred biochemical marker is PAPP-A rather than PlGF, especially when biochemical testing is carried out during the 11^th week of gestation or earlier. However, if PlGF was to be used rather than PAPP-A, the same detection rate can be achieved but at a higher FPR. This may be an acceptable compromise to minimize cost and achieve effective screening for both trisomy and PE. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Cardiac function in gestational diabetes mellitus: A longitudinal study from fetal life to infancy

OBJECTIVE

To determine whether cardiac functional and structural changes in fetuses of mothers with gestational diabetes mellitus (GDM) persist in the offspring beyond the neonatal period.

DESIGN

Longitudinal study.

SETTING

Fetal Medicine Unit in a UK teaching hospital.

METHODS

73 women with GDM and 73 women with uncomplicated pregnancy were recruited and fetal cardiac scans were performed at 35-36 weeks' gestation. Repeat echocardiogram was performed in their offspring during infancy.

MAIN OUTCOME MEASURES

Fetal and infant cardiac functional and structural changes.

RESULTS

Fetuses of mothers with GDM, compared with controls, had more globular right ventricles (sphericity index 0.7, interquartile range [IQR] 0.6/0.7 versus 0.6, IQR 0.5/0.6, P < 0.001) and reduced right global longitudinal systolic strain (-16.4, IQR -18.9/-15.3 versus -18.5, IQR -20.6/-16.8, P = 0.001) and left global longitudinal systolic strain (-20.1, IQR -22.5/-16.9 versus -21.3, IQR -23.5/-19.5), P = 0.021). In the GDM group, compared with controls, in infancy there was higher left ventricular E/e' (8.7, IQR 7.3/9.7 versus 7.9 IQR, 6.8/8.9 P = 0.011) and lower left ventricular global longitudinal systolic strain (-21.0, IQR -22.5/-19.4 versus -22.3, IQR -23.5/-20.7, P = 0.001) and tricuspid annular plane systolic excursion (13.8, IQR 12.7/16.1 versus 15.2, IQR 13.8/16.8, P = 0.003). These differences remained following multivariable analysis.

CONCLUSION

Gestational diabetes mellitus is associated with alterations in fetal cardiac function and structure compared with controls and persistent cardiac changes in infancy.

TWEETABLE ABSTRACT

Gestational diabetes mellitus, even when well controlled, is associated with fetal cardiac changes and these persist in infancy.

Maternal cardiac function in gestational diabetes mellitus at 35-36 weeks' gestation and 6 months postpartum

OBJECTIVE

Women with gestational diabetes mellitus (GDM) are at increased risk for adverse cardiovascular outcome later in life. However, it is uncertain whether this increased risk is due to cardiovascular changes occurring during pregnancy and persisting thereafter or to an adverse underlying cardiovascular risk factor profile. Some studies have reported that GDM is associated with reduced systolic and diastolic left ventricular function in pregnancy; however, it remains unknown whether these changes persist after delivery. The objective of this study was to compare cardiac function and structure in women with GDM and those with uncomplicated pregnancy at 35-36 weeks' gestation and about 6 months after delivery.

METHODS

This was a longitudinal study in which women with GDM and those with uncomplicated pregnancy had detailed cardiovascular assessment at 35-36 weeks' gestation and repeat examination around 6 months after delivery. In all women, left ventricular systolic and diastolic indices were measured and left ventricular mass indexed for body surface area was calculated. Cardiac output and peripheral vascular resistance were also calculated using echocardiography. Linear mixed model analysis accounting for differences in maternal characteristics was carried out to compare findings of cardiovascular function between the GDM group and controls and within each group at 35-36 weeks' gestation and at 6 months after delivery.

RESULTS

We studied 73 women with GDM and 73 controls with uncomplicated pregnancy. At 35-36 weeks' gestation, women with GDM, compared to controls, had higher E/e' ratio and lower E/A ratio and global longitudinal systolic strain; there were no significant differences between the groups in ejection fraction. Left ventricular mass indexed for body surface area was also increased in women with GDM. There were no significant differences between the groups in cardiac output and peripheral vascular resistance. At 6 months after delivery, cardiac functional indices improved in both patients with GDM and controls, but in the GDM group, compared to controls, there was a lower degree of improvement in E/A ratio and global longitudinal systolic strain.

CONCLUSION

In the third trimester, patients with GDM have subtle differences in diastolic and systolic left ventricular function compared to controls and, despite improvement after delivery, these changes persist for at least 6 months. Long-term follow-up is therefore needed to assess whether women with GDM are at risk for an accelerated decline in their cardiac function and, if so, whether this trend can be reversed or delayed by optimal cardiovascular risk factor modification. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Competing-risks model for prediction of small-for-gestational-age neonate from maternal characteristics and medical history

BACKGROUND

The established method of identifying a group of women at high risk of delivering a small-for-gestational-age (SGA) neonate, requiring increased surveillance, is use of risk scoring systems based on maternal demographic characteristics and medical history. Although this approach is relatively simple to perform, it does not provide patient-specific risks and has an uncertain performance in predicting SGA. Another approach to predict delivery of a SGA neonate is to use logistic regression models that combine maternal factors with first-trimester biomarkers. These models provide patient-specific risks for different prespecified cut-offs of birth-weight percentile and gestational age (GA) at delivery.

OBJECTIVES

First, to develop a competing-risks model for prediction of SGA based on maternal demographic characteristics and medical history, in which GA at the time of delivery and birth-weight Z-score are treated as continuous variables. Second, to compare the predictive performance of the new model for SGA neonates to that of previous methods.

METHODS

This was a prospective observational study in 124 443 women with singleton pregnancy undergoing routine ultrasound examination at 11 + 0 to 13 + 6 weeks' gestation. The dataset was divided randomly into a training and a test dataset. The training dataset was used to develop a model for the joint distribution of GA at delivery and birth-weight Z-score from variables of maternal characteristics and medical history. This patient-specific joint Gaussian distribution of GA at delivery and birth-weight Z-score allows risk calculation for SGA defined in terms of different birth-weight percentiles and GA. The new model was then validated in the test dataset to assess performance of screening and we compared its predictive performance to that of logistic regression models for different SGA definitions.

RESULTS

In the new model, the joint Gaussian distribution of GA at delivery and birth-weight Z-score is shifted to lower GA at delivery and birth-weight Z-score values, resulting in an increased risk for SGA, by lower maternal weight and height, black, East Asian, South Asian and mixed racial origin, medical history of chronic hypertension, diabetes mellitus and systemic lupus erythematosus and/or antiphospholipid syndrome, conception by in-vitro fertilization and smoking. In parous women, variables from the last pregnancy that increased the risk for SGA were history of pre-eclampsia or stillbirth, decreasing birth-weight Z-score and decreasing GA at delivery of the last pregnancy and interpregnancy interval < 0.5 years. In the test dataset, at a false-positive rate of 10%, the new model predicted 30.1%, 32.1%, 32.2% and 37.8% of cases of a SGA neonate with birth weight < 10^th percentile delivered at < 42, < 37, < 34 and < 30 weeks' gestation, respectively, which were similar or higher than the respective values achieved by a series of logistic regression models. The calibration study demonstrated good agreement between the predicted risks and the observed incidence of SGA in both the training and test datasets.

CONCLUSIONS

A new competing-risks model, based on maternal characteristics and medical history, provides estimation of patient-specific risks for SGA in which GA at delivery and birth-weight Z-score are treated as continuous variables. Such estimation of the a-priori risk for SGA is an essential first step in the use of Bayes' theorem to combine maternal factors with biomarkers for the continuing development of more effective methods of screening for SGA. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Effect of race on longitudinal central hemodynamics in pregnancy

OBJECTIVE

To compare central hemodynamics between white, black and Asian women in pregnancy.

METHODS

This was a prospective, longitudinal study of maternal central hemodynamics in white, black and Asian women with a singleton pregnancy, assessed using a bioreactance method at 11 + 0 to 13 + 6, 19 + 0 to 24 + 0, 30 + 0 to 34 + 0 and 35 + 0 to 37 + 0 weeks' gestation. At each visit, cardiac output (CO), stroke volume (SV), heart rate (HR), peripheral vascular resistance (PVR) and mean arterial pressure were recorded. Multilevel linear mixed-effects analysis was performed to compare the repeated measures of the cardiac variables between white, black and Asian women, controlling for maternal characteristics, medical history and medication use.

RESULTS

The study population included 1165 white, 247 black and 116 Asian women. CO increased with gestational age to a peak at 32 weeks and then decreased; the highest CO was observed in white women and the lowest in Asian women. SV initially increased after the first visit but subsequently declined with gestational age in white women, decreased with gestational age in black women and remained static in Asian women. In all three study groups, HR increased with gestational age until 32 weeks and then remained constant; HR was highest in black women and lowest in white women. PVR showed a reversed pattern to that of CO; the highest values were in Asian women and the lowest in white women. The least favorable hemodynamic profile, which was observed in black and Asian women, was reflected in higher rates of a small-for-gestational-age infant.

CONCLUSIONS

There are race-specific differences in maternal cardiac adaptation to pregnancy. White women have the most favorable cardiac adaptation by increasing SV and HR, achieving the highest CO and lowest PVR. In contrast, black and Asian women have lower CO and higher PVR than do white women, with CO increasing through a rise in HR due to declining or static SV. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Clinical validation of bioreactance for the measurement of cardiac output in pregnancy

Maternal cardiac dysfunction is associated with pre-eclampsia, fetal growth restriction and haemodynamic instability during obstetric anaesthesia. There is growing interest in the use of non-invasive cardiac output monitoring to guide antihypertensive and fluid therapies in obstetrics. The aim of this study was to validate thoracic bioreactance using the NICOM® instrument against transthoracic echocardiography in pregnant women, and to assess the effects of maternal characteristics on the absolute difference of stroke volume, cardiac output and heart rate. We performed a prospective study involving women with singleton pregnancies in each trimester. We recruited 56 women who were between 11 and 14 weeks gestation, 57 between 20 and 23 weeks, and 53 between 35 and 37 weeks. Cardiac output was assessed repeatedly and simultaneously over 5 min in the left lateral position with NICOM and echocardiography. The performance of NICOM was assessed by calculating bias, 95% limits of agreement and mean percentage difference relative to echocardiography. Multivariate regression analysis evaluated the effect of maternal characteristics on the absolute difference between echocardiography and NICOM. The mean percentage difference of cardiac output measurements between the two methods was ±17%, with mean bias of -0.13 l.min^-1 and limits of agreement of -1.1 to 0.84; stroke volume measurements had a mean percentage difference of ±15%, with a mean bias of -0.8 ml (-10.9 to 12.6); and heart rate measurements had a mean percentage difference of ±6%, with a mean bias of -2.4 beats.min^-1 (-6.9 to 2.0). Similar results were found when the analyses were confined to each individual trimester. The absolute difference between NICOM and echocardiography was not affected by maternal age, weight, height, race, systolic or diastolic blood pressure. In conclusion, NICOM demonstrated good agreement with echocardiography, and can be used in pregnancy for the measurement of cardiac function.

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.

Prevention of stillbirth: impact of two-stage screening for vasa previa

OBJECTIVES

To examine the feasibility and effectiveness of a two-stage ultrasound screening strategy for detection of vasa previa and to estimate the potential impact of screening on prevention of stillbirth.

METHODS

This was a retrospective study of data from prospective screening for vasa previa in singleton pregnancies, undertaken at the Fetal Medicine Unit at Medway Maritime Hospital, UK, between 2012 and 2018. Women booked for prenatal care and delivery in our hospital had routine ultrasound examinations at 11-13 and 20-22 weeks' gestation. Those with velamentous cord insertion at the inferior part of the placenta at the first-trimester scan and those with low-lying placenta at the second-trimester scan were classified as high-risk for vasa previa and had transvaginal sonography searching specifically for vasa previa, at the time of the 20-22-week scan. The management and outcome of cases with suspected vasa previa is described. We excluded cases of miscarriage or termination at < 24 weeks' gestation.

RESULTS

The study population of 26 830 singleton pregnancies included 21 (0.08%; 1 in 1278) with vasa previa. In all cases of vasa previa, the diagnosis was made at the 20-22-week scan and confirmed postnatally by gross and histological examination of the placenta. At the 11-13-week scan, cord insertion was classified as central in 25 071 (93.4%) cases, marginal in 1680 (6.3%), and velamentous in 79 (0.3%). In 16 (76.2%) of the 21 cases of vasa previa, cord insertion at the first-trimester scan was classified as velamentous at the inferior part of the placenta, in two cases (9.5%) as marginal and in three cases (14.3%) as central. The 21 cases of vasa previa were managed on an outpatient basis with serial scans for measurement of cervical length and elective Cesarean section at 34 weeks' gestation; all babies were liveborn but there was one neonatal death. In the study population, there were 83 stillbirths, none of which had evidence of vasa previa on postnatal examination. On the assumption that, if we had not diagnosed prenatally all 21 cases of vasa previa in our population, half of these cases would have resulted in stillbirth, then the potential impact of screening is prevention of 10.6% (10/94) of stillbirths.

CONCLUSION

A two-stage strategy of screening for vasa previa can be incorporated into routine clinical practice, and such a strategy could potentially reduce the rate of stillbirth. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Twin pregnancy with two live fetuses at 11-13 weeks: effect of one fetal death on pregnancy outcome

OBJECTIVES

First, to compare the incidence of single and double fetal death between monochorionic (MC) and dichorionic (DC) twin pregnancies with two live fetuses at 11-13 weeks' gestation and no major abnormalities. Second, to investigate the relationship between gestational age at single fetal death and interval to delivery of the cotwin. Third, to determine the rate of early preterm birth in DC and MC twin pregnancies with two live fetuses and those with single fetal death.

METHODS

This was a retrospective analysis of prospectively collected data on twin pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation between 2002 and 2019. The outcome measures, which were stratified by chorionicity, were: first, death of both fetuses at presentation or death of one fetus followed by delivery of a live or dead cotwin within the subsequent 3 days at < 34 weeks' gestation; second, in pregnancies with single fetal death at < 34 weeks' gestation and a live cotwin ≥ 3 days later, the subsequent risk of fetal death and gestational-age distribution at birth of the cotwin; and, third, the gestational-age distribution at birth in pregnancies with two live fetuses.

RESULTS

The main findings of this study of 4896 DC and 1329 MC twin pregnancies with two live fetuses at 11-13 weeks' gestation were: first, the rate of death of both twins or death of one fetus and delivery of the live or dead cotwin within 3 days was higher in MC than in DC twin pregnancies; second, the rate of single fetal death with a live cotwin ≥ 3 days later was higher in MC than in DC twin pregnancies, but the rate of subsequent cotwin death in MC twin pregnancies was not significantly different from that in DC twin pregnancies; third, in pregnancies with two live fetuses, the rate of early preterm birth was significantly higher in MC than in DC twin pregnancies; fourth, the rate of early preterm birth in pregnancies with single fetal death and a live cotwin ≥ 3 days later was not significantly different between MC and DC twin pregnancies but the rates were substantially higher than in those with two live fetuses; and, fifth, in both MC and DC pregnancies with single fetal death and a live cotwin ≥ 3 days later, there was a significant inverse association between gestational age at death and interval to delivery (mean interval of 19 weeks for death at 15 weeks and mean interval of 2.5 weeks for death at 30 weeks).

CONCLUSIONS

First, in MC twin pregnancies, the risk of single or double fetal death is higher than in DC twins. Second, in both MC and DC twin pregnancies, the rate of early preterm birth is higher in those with one fetal death than in those with two live fetuses. Third, in both MC and DC twins with one fetal death, the interval to delivery is related inversely to gestational age at fetal death. These data should be useful in counseling parents as to the likely outcome of their pregnancy after single fetal death and in defining strategies for surveillance in the management of these types of twin pregnancy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Diagnosis of fetal defects in twin pregnancies at routine 11-13-week ultrasound examination

OBJECTIVES

To examine the performance of the routine 11-13-week scan in detecting fetal defects in twin pregnancies and to examine if, in pregnancies with a fetal defect, compared to those with normal fetuses, there is increased incidence of nuchal translucency thickness (NT) ≥ 95^th and ≥ 99^th percentiles or intertwin discordance in crown-rump length (CRL) ≥ 10% and ≥ 15%.

METHODS

This was a retrospective analysis of prospectively collected data in twin pregnancies undergoing routine ultrasound examination for fetal anatomy, according to standardized protocols, at 11-13 weeks' gestation between 2002 and 2019. Pregnancies with known chromosomal abnormality were excluded. The final diagnosis of fetal defect was based on the results of postnatal examination in cases of live birth and on the findings of the last ultrasound examination in cases of pregnancy termination, miscarriage or stillbirth. The performance of the 11-13-week scan in the detection of fetal defects was determined.

RESULTS

The study population of 6366 twin pregnancies with two live fetuses at 11-13 weeks' gestation included 4979 (78.2%) dichorionic (DC) and 1387 (21.8%) monochorionic (MC) twin pregnancies. The main findings were: first, the overall incidence of fetal defects was higher in MC than in DC twins (2.8% vs 1.3%); second, the proportion of defects diagnosed in the first trimester was higher in MC than in DC twins (52.6% vs 27.1%); third, the pattern of defects in relation to detectability at the 11-13-week scan (always detectable, sometimes detectable and never detectable) was similar to that reported previously in singleton pregnancies; fourth, always-detectable defects included acrania, alobar holoprosencephaly, encephalocele, pentalogy of Cantrell, exomphalos, body-stalk anomaly, twin reversed arterial perfusion sequence and conjoined twins; fifth, the incidence of fetal NT ≥ 95^th percentile was higher in those with than in those without a defect (16.5% vs 4.5% in DC twins and 19.2% vs 5.9% in MC twins) and this was also true for NT ≥ 99^th percentile (8.3% vs 1.0% in DC twins and 15.4% vs 2.0% in MC twins); and sixth, the incidence of CRL discordance ≥ 10% was higher in those with than in those without a defect (20.2% vs 7.9% in DC twins and 33.8% vs 9.3% in MC twins) and this was also true for CRL discordance ≥ 15% (10.1% vs 1.9% in DC twins and 28.2% vs 2.8% in MC twins).

CONCLUSIONS

First, fetal defects are more common in MC than in DC twin pregnancies. Second, first-trimester detection of fetal defects in DC twin pregnancies is similar to that in singleton pregnancies. Third, first-trimester detectability of defects in MC twins is higher than in DC twins. Fourth, in twin pregnancies with a fetal defect, there is higher intertwin discordance in CRL and incidence of increased NT, but the predictive performance of screening by these markers is poor. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Maternal cardiac function in women at high risk for pre-eclampsia treated with 150 mg aspirin or placebo: an observational study

OBJECTIVE

To compare maternal haemodynamics in women at low and high risk for preterm pre-eclampsia (PE), and between those at high risk who are randomised to aspirin or placebo.

DESIGN

Prospective, longitudinal observational study.

SETTING

Maternity units in six UK hospitals.

POPULATION

Women participating in the Aspirin for Prevention of Preterm Pre-eclampsia (ASPRE) trial. The population comprised three groups of women: low risk for preterm PE (n = 1362), high risk for preterm PE treated with aspirin (n = 208) and high risk for preterm PE on placebo (n = 220).

METHODS

Women had four visits during pregnancy: 11-14, 19-24, 30-34, and 35-37 weeks' gestation. Blood pressure was measured with a device validated for pregnancy, and PE and maternal haemodynamics were assessed with a bioreactance monitor at each visit. A multilevel linear mixed-effects analysis was performed to examine longitudinal changes of maternal haemodynamic variables, controlling for demographic characteristics, past medical history and medication use.

MAIN OUTCOME MEASURES

Longitudinal changes of cardiac output (CO), mean arterial pressure (MAP), and peripheral vascular resistance (PVR).

RESULTS

The low-risk group demonstrated the expected changes with an increase in CO and reduction in MAP and PVR, with a quadratic change across gestation. In contrast, the high-risk groups had a declining CO, and higher MAP and PVR during pregnancy. The administration of aspirin did not appear to affect maternal haemodynamics.

CONCLUSIONS

Women screened as high risk for preterm PE have a pathological cardiac adaptation to pregnancy and the prophylactic use of aspirin (150 mg oral daily from the first trimester) in this group may not alter this haemodynamic profile.

TWEETABLE ABSTRACT

In women at high risk of pre-eclampsia, prophylactic use of aspirin may not alter the impaired maternal cardiac adaptation.

Increased nuchal translucency at 11-13 weeks' gestation and outcome in twin pregnancy

OBJECTIVE

To investigate the value of increased fetal nuchal translucency thickness (NT) at the 11-13-week scan in the prediction of adverse outcome in dichorionic (DC), monochorionic diamniotic (MCDA) and monochorionic monoamniotic (MCMA) twin pregnancies.

METHODS

This was a retrospective analysis of prospectively collected data on twin pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation between 2002 and 2019. In pregnancies with no major defects or chromosomal abnormalities, we examined the value of increased NT ≥ 95^th percentile in one or both fetuses in the prediction of, first, miscarriage or death of one or both fetuses at < 20 and < 24 weeks' gestation in DC, MCDA and MCMA twin pregnancies, second, death of one or both fetuses or neonates at ≥ 24 weeks in DC, MCDA and MCMA twin pregnancies, third, development of twin-twin transfusion syndrome (TTTS) or selective fetal growth restriction (sFGR) treated by endoscopic laser surgery at < 20 and ≥ 20 weeks' gestation in MCDA pregnancies, and, fourth, either fetal loss or laser surgery at < 20 weeks' gestation in MCDA pregnancies.

RESULTS

The study population of 6225 twin pregnancies included 4896 (78.7%) DC, 1274 (20.5%) MCDA and 55 (0.9%) MCMA pregnancies. The incidence of NT ≥ 95^th percentile in one or both fetuses in DC twin pregnancies was 8.3%; in MCDA twins the incidence was significantly higher (10.4%; P = 0.016), but in MCMA twins it was not significantly different (9.1%; P = 0.804) from that in DC twins. In DC twin pregnancies, the incidence of high NT was not significantly different between those with two survivors and those with adverse outcome. In MCMA twin pregnancies, the number of cases was too small for meaningful assessment of the relationship between high NT and adverse outcome. In MCDA twin pregnancies with at least one fetal death or need for endoscopic laser surgery at < 20 weeks' gestation, the incidence of NT ≥ 95^th percentile was significantly higher than in those with two survivors (23.5% vs 9.8%; P < 0.0001). Kaplan-Meier analysis in MCDA twin pregnancies showed that, in those with NT ≥ 95^th percentile, there was significantly lower survival at < 20 weeks' gestation than in those with NT < 95^th percentile (P = 0.001); this was not the case for survival at ≥ 20 weeks (P = 0.960). The performance of screening by fetal NT ≥ 95^th percentile for prediction of either fetal loss or need for endoscopic laser surgery at < 20 weeks' gestation was poor, with a detection rate of 23.5% at a false-positive rate of 8.9%, and the relative risk, in comparison to fetal NT < 95^th percentile, was 2.640 (95% CI, 1.854-3.758; P < 0.0001). In MCDA twin pregnancies, the overall rate of fetal loss or need for laser surgery at < 20 weeks' gestation was 10.7% but, in the subgroups with NT ≥ 95^th and NT ≥ 99^th percentiles, which constituted 10.4% and 3.3% of the total, the rates increased to 24.1% and 40.5%, respectively.

CONCLUSIONS

In MCDA twin pregnancies with no major fetal abnormalities, measurement of NT at the 11-13-week scan is a poor screening test for adverse pregnancy outcome. However, the finding in one or both fetuses of NT ≥ 95^th percentile, and more so ≥ 99^th percentile, is associated with a substantially increased risk of fetal loss or need for endoscopic laser surgery at < 20 weeks' gestation. The extent to which closer monitoring and earlier intervention in the high-risk group can reduce these complications remains to be determined. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

First-trimester screening for trisomies in pregnancies with vanishing twin

OBJECTIVES

To examine multiples of the median (MoM) values of serum free beta-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) in a large series of pregnancies with a vanishing twin, determine the association of these values with the interval between embryonic death and blood sampling, and develop a model that would allow incorporation of these metabolites in first-trimester combined screening for trisomy.

METHODS

This was a retrospective study comparing maternal serum free β-hCG and PAPP-A levels at 11-13 weeks' gestation in 528 dichorionic pregnancies with a vanishing twin, including 194 (36.7%) with an empty gestational sac and 334 (63.3%) with a dead embryo, with those in 5280 normal singleton pregnancies matched for method of conception and date of examination. In vanishing-twin pregnancies with a dead embryo, marker levels were examined in relation to the estimated time between embryonic death and maternal blood sampling.

RESULTS

First, in pregnancies with a vanishing twin, median free β-hCG MoM was not significantly different from that in normal singleton pregnancies (1.000; 95% CI, 0.985-1.016 vs 0.995; 95% CI, 0.948-1.044; P = 0.849). Second, PAPP-A MoM was higher in vanishing-twin pregnancies than in normal singleton pregnancies (1.000; 95% CI, 0.985-1.015), both in the group with an empty gestational sac (1.165; 95% CI, 1.080-1.256; P = 0.0001) and in that with a dead embryo (1.175; 95% CI, 1.105-1.249; P < 0.0001). Third, in vanishing-twin pregnancies with a dead embryo, PAPP-A MoM was related inversely to the interval between estimated gestational age at embryonic demise and blood sampling (P < 0.0001). Fourth, in first-trimester screening for trisomy 21 in singleton pregnancies, the estimated detection rate, at a 5% false-positive rate, was 82% in screening by a combination of maternal age and fetal nuchal translucency thickness, and this increased to 86% with the addition of serum free β-hCG and to 91% with the addition of serum PAPP-A. Fifth, similar performance of screening can be achieved in pregnancies with a vanishing twin, provided the appropriate adjustments are made to the level of PAPP-A for the interval between estimated gestational age at embryonic demise and blood sampling.

CONCLUSIONS

First-trimester screening for trisomy in pregnancies with a vanishing twin should rely on a combination of maternal age, fetal nuchal translucency thickness and serum free β-hCG, as in singleton pregnancy, without the use of serum PAPP-A. Alternatively, PAPP-A can be included but only after appropriate adjustment for the interval between estimated gestational age at fetal demise and blood sampling. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Comparison of different methods of measuring angle of progression in prediction of labor outcome

OBJECTIVES

First, to compare the manual sagittal and parasagittal and automated parasagittal methods of measuring the angle of progression (AoP) by transperineal ultrasound during labor, and, second, to develop models for the prediction of time to delivery and need for Cesarean section (CS) for failure to progress (FTP) in a population of patients undergoing induction of labor.

METHODS

This was a prospective observational study of transperineal ultrasound in a cohort of 512 women with a singleton pregnancy undergoing induction of labor. A random selection of 50 stored images was assessed for inter- and intraobserver reliability of AoP measurements using the manual sagittal and parasagittal and automated parasagittal methods. In cases of vaginal delivery, univariate linear, multiple linear and quantile regression analyses were performed to predict time to delivery. Univariate and multivariate binomial logistic regression analyses were performed to predict CS for FTP in the first stage of labor.

RESULTS

The intraclass correlation coefficient (ICC) for the manual parasagittal method for a single observer was 0.97 (95% CI, 0.95-0.98) and for two observers it was 0.96 (95% CI, 0.93-0.98), indicating good reliability. The ICC for the sagittal method for a single observer was 0.93 (95% CI, 0.88-0.96) and for two observers it was 0.74 (95% CI, 0.58-0.84), indicating moderate reliability for a single observer and poor reliability between two observers. Bland-Altman analysis demonstrated narrower limits of agreement for the manual parasagittal approach than for the sagittal approach for both a single and two observers. The automated parasagittal method failed to capture an image in 19% of cases. The mean difference in AoP measurements between the sagittal and manual parasagittal methods was 11°. In pregnancies resulting in vaginal delivery, 54% of the variation in time to delivery was explained in a model combining parity, epidural and syntocinon use during labor and the sonographic findings of fetal head position and AoP. In the prediction of CS for FTP in the first stage of labor, a model which combined maternal factors with the sonographic measurements of AoP and estimated fetal weight was superior to one utilizing maternal factors alone (area under the receiver-operating-characteristics curve, 0.80 vs 0.76).

CONCLUSIONS

First, the method of measuring AoP with the greatest reliability is the manual parasagittal technique and future research should focus on this technique. Second, over half of the variation in time to vaginal delivery can be explained by a model that combines maternal factors, pregnancy characteristics and ultrasound findings. Third, the ability of AoP to provide clinically useful prediction of CS for FTP in the first stage of labor is limited. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Intertwin discordance in fetal size at 11-13 weeks' gestation and pregnancy outcome

OBJECTIVE

To investigate the value of intertwin discordance in fetal crown-rump length (CRL) at the 11-13-week scan in the prediction of adverse outcome in dichorionic (DC), monochorionic diamniotic (MCDA) and monochorionic monoamniotic (MCMA) twin pregnancies.

METHODS

This was a retrospective analysis of prospectively collected data on twin pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation between 2002 and 2019. In pregnancies with no major abnormalities, we examined the value of intertwin discordance in fetal CRL in DC, MCDA and MCMA twins in the prediction of fetal loss at < 20 and < 24 weeks' gestation, perinatal death at ≥ 24 weeks, preterm delivery at < 32 and < 37 weeks, birth of at least one small-for-gestational-age (SGA) neonate with birth weight < 5^th percentile and intertwin birth-weight discordance of ≥ 20% and ≥ 25%.

RESULTS

First, the study population of 6225 twin pregnancies included 4896 (78.7%) DC, 1274 (20.4%) MCDA and 55 (0.9%) MCMA twin pregnancies. Second, median CRL discordance in DC twin pregnancies (3.2%; interquartile range (IQR), 1.4-5.8%) was lower than in MCDA twins (3.6%; IQR, 1.6-6.2%; P = 0.0008), but was not significantly different from that in MCMA twins (2.9%; IQR, 1.2-5.1%; P = 0.269). Third, compared to CRL discordance in DC twin pregnancies with two non-SGA live births at ≥ 37 weeks' gestation, there was significantly larger CRL discordance in both DC and MCDA twin pregnancies complicated by fetal death at < 20 and < 24 weeks' gestation, perinatal death at ≥ 24 weeks, preterm birth at < 32 and < 37 weeks, birth of at least one SGA neonate and birth-weight discordance ≥ 20% and ≥ 25%, and in MCDA twin pregnancies undergoing endoscopic laser surgery. Fourth, the predictive performance of CRL discordance for each adverse pregnancy outcome was poor, with areas under the receiver-operating-characteristics curves ranging from 0.533 to 0.624. However, in both DC and MCDA twin pregnancies with large CRL discordance, there was a high risk of fetal loss. Fifth, in DC twin pregnancies, the overall rate of fetal loss at < 20 weeks' gestation was 1.3% but, in the small subgroup with CRL discordance of ≥ 15%, which constituted 1.9% of the total, the rate increased to 5.3%. Sixth, in MCDA twin pregnancies, the rate of fetal loss or endoscopic laser surgery at < 20 weeks was about 11%, but, in the small subgroups with CRL discordance of ≥ 10%, ≥ 15% and ≥ 20%, which constituted 9%, < 3% and < 1% of the total, the risk was increased to about 32%, 49% and 70%, respectively. Seventh, in MCMA twin pregnancies, there were no significant differences in CRL discordance for any of the adverse outcome measures, but this may be the consequence of the small number of cases in the study population.

CONCLUSIONS

In both DC and MCDA twin pregnancies, increased CRL discordance is associated with an increased risk of fetal death at < 20 and < 24 weeks' gestation, perinatal death at ≥ 24 weeks, preterm birth at < 37 and < 32 weeks, birth of at least one SGA neonate and birth-weight discordance ≥ 20% and ≥ 25%, but CRL discordance is a poor screening test for adverse pregnancy outcome. However, in DC twins, CRL discordance of ≥ 15% is associated with an increased risk of fetal loss at < 20 and < 24 weeks' gestation and, in MCDA twins, CRL discordance of ≥ 10%, and more so discordance of ≥ 15% and ≥ 20%, is associated with a very high risk of fetal loss or endoscopic laser surgery at < 20 and < 24 weeks and this information is useful in counseling women and defining the timing for subsequent assessment and possible intervention. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Impact of biometric measurement error on identification of small- and large-for-gestational-age fetuses

OBJECTIVES

First, to obtain measurement-error models for biometric measurements of fetal abdominal circumference (AC), head circumference (HC) and femur length (FL), and, second, to examine the impact of biometric measurement error on sonographic estimated fetal weight (EFW) and its effect on the prediction of small- (SGA) and large- (LGA) for-gestational-age fetuses with EFW < 10^th and > 90^th percentile, respectively.

METHODS

Measurement error standard deviations for fetal AC, HC and FL were obtained from a previous large study on fetal biometry utilizing a standardized measurement protocol and both qualitative and quantitative quality-control monitoring. Typical combinations of AC, HC and FL that gave EFW on the 10^th and 90^th percentiles were determined. A Monte-Carlo simulation study was carried out to examine the effect of measurement error on the classification of fetuses as having EFW above or below the 10^th and 90^th percentiles.

RESULTS

Errors were assumed to follow a Gaussian distribution with a mean of 0 mm and SDs, obtained from a previous well-conducted study, of 6.93 mm for AC, 5.15 mm for HC and 1.38 mm for FL. Assuming errors according to such distributions, when the 10^th and 90^th percentiles are used to screen for SGA and LGA fetuses, respectively, the detection rates would be 78.0% at false-positive rates of 4.7%. If the cut-offs were relaxed to the 30^th and 70^th percentiles, the detection rates would increase to 98.2%, but at false-positive rates of 24.2%. Assuming half of the spread in the error distribution, using the 10^th and 90^th percentiles to screen for SGA and LGA fetuses, respectively, the detection rates would be 86.6% at false-positive rates of 2.3%. If the cut-offs were relaxed to the 15^th and 85^th percentiles, respectively, the detection rates would increase to 97.0% and the false-positive rates would increase to 6.3%.

CONCLUSIONS

Measurement error in fetal biometry causes substantial error in EFW, resulting in misclassification of SGA and LGA fetuses. The extent to which improvement can be achieved through effective quality assurance remains to be seen but, as a first step, it is important for practitioners to understand how biometric measurement error impacts the prediction of SGA and LGA fetuses. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Value of routine ultrasound examination at 35-37 weeks' gestation in diagnosis of non-cephalic presentation

OBJECTIVE

Undiagnosed non-cephalic presentation in labor carries increased risks for both the mother and baby. Routine pregnancy care based on maternal abdominal palpation fails to detect the majority of cases of non-cephalic presentation. The aim of this study was to report the incidence of non-cephalic presentation at a routine scan at 35 + 0 to 36 + 6 weeks' gestation and the subsequent management of such pregnancies.

METHODS

This was a retrospective analysis of prospectively collected data in 45 847 singleton pregnancies that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. Patients with breech or transverse/oblique presentation were divided into two groups; first, those who would have elective Cesarean section for fetal or maternal indications other than the abnormal presentation, and, second, those who would potentially require external cephalic version (ECV). The latter group was reassessed after 1-2 weeks and, if there was persistence of abnormal presentation, the parents were offered the option of ECV or elective Cesarean section at 38-40 weeks' gestation. Multivariable logistic regression analysis was carried out to determine which of the factors from maternal and pregnancy characteristics provided a significant contribution in the prediction of, first, non-cephalic presentation at the 35 + 0 to 36 + 6-week scan, second, successful ECV from non-cephalic to cephalic presentation, and, third, spontaneous rotation from non-cephalic to cephalic presentation that persisted until delivery.

RESULTS

First, at 35 + 0 to 36 + 6 weeks, the fetal presentation was cephalic in 43 416 (94.7%) pregnancies, breech in 1987 (4.3%) and transverse or oblique in 444 (1.0%). Second, multivariable analysis demonstrated that the risk of non-cephalic presentation increased with increasing maternal age and weight, decreasing height and earlier gestational age at scan, was higher in the presence of placenta previa, oligohydramnios or polyhydramnios and in nulliparous than parous women, and was lower in women of South Asian or mixed racial origin than in white women. Third, 22% of cases of non-cephalic presentation were not eligible for ECV because of planned Cesarean section for indications other than the malpresentation. Fourth, of those eligible for ECV, only 48.5% (646/1332) agreed to the procedure, which was successful in 39.0% (252/646) of cases. Fifth, the chance of successful ECV increased with increasing maternal age and was lower in nulliparous than parous women. Sixth, in 33.9% (738/2179) of pregnancies with non-cephalic presentation in which successful ECV was not carried out, there was subsequent spontaneous rotation to cephalic presentation. Seventh, the chance of spontaneous rotation from non-cephalic to cephalic presentation increased with increasing interval between the scan and delivery, decreased with increasing birth-weight percentile, was higher in women of black than those of white racial origin, if presentation was transverse or oblique rather than breech and if there was polyhydramnios, and was lower in nulliparous than parous women and in the presence of placenta previa. Eighth, in 109 (0.3%) cephalic presentations, there was subsequent rotation to non-cephalic presentation and, in 41% of these, the diagnosis was made during labor. Ninth, of the total 2431 cases of non-cephalic presentation at the time of the scan, presentation at birth was cephalic in 985 (40.5%); in 738 (74.9%) this was due to spontaneous rotation and in 247 (25.1%) this was due to successful ECV. Tenth, prediction of non-cephalic presentation at the 35 + 0 to 36 + 6-week scan and successful ECV from maternal and pregnancy factors was poor, but prediction of spontaneous rotation from non-cephalic to cephalic presentation that persisted until delivery was moderately good and this could be incorporated in the counseling of women prior to ECV.

CONCLUSIONS

The problem of unexpected non-cephalic presentation in labor can, to a great extent, be overcome by a routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. The incidence of non-cephalic presentation at the 35 + 0 to 36 + 6-week scan was about 5%, but, in about 40% of these cases, the presentation at birth was cephalic, mainly due to subsequent spontaneous rotation and, to a lesser extent, as a consequence of successful ECV. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Outcome of twin pregnancy with two live fetuses at 11-13 weeks' gestation

OBJECTIVES

To report and compare pregnancy outcome in dichorionic (DC), monochorionic diamniotic (MCDA) and monochorionic monoamniotic (MCMA) twin pregnancies with two live fetuses at 11-13 weeks' gestation and to examine the impact of endoscopic laser surgery for severe twin-twin transfusion syndrome (TTTS) and/or selective fetal growth restriction (sFGR) on the outcome of MCDA twins.

METHODS

This was a retrospective analysis of prospectively collected data on twin pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation between 2002 and 2019. In pregnancies with no major abnormalities, we compared overall survival, fetal loss at < 24 weeks' gestation, perinatal death at ≥ 24 weeks, delivery at < 37 and < 32 weeks, and birth weight < 5^th percentile between DC, MCDA and MCMA twins.

RESULTS

The study population of 6225 twin pregnancies with two live fetuses at 11-13 weeks' gestation with no major abnormalities included 4896 (78.7%) DC, 1274 (20.5%) MCDA and 55 (0.9%) MCMA twins. In DC twins, the rate of loss at < 24 weeks' gestation in all fetuses was 2.3%; this rate was higher in MCDA twins (7.7%; relative risk (RR), 3.258; 95% CI, 2.706-3.923) and more so in MCMA twins (21.8%; RR, 9.289; 95% CI, 6.377-13.530). In DC twins, the rate of perinatal death at ≥ 24 weeks in all twins that were alive at 24 weeks was 1.0%; this rate was higher in MCDA twins (2.5%; RR, 2.456; 95% CI, 1.779-3.389) and more so in MCMA twins (9.3%; RR, 9.130; 95% CI, 4.584-18.184). In DC twins, the rate of preterm birth at < 37 weeks' gestation in pregnancies with at least one liveborn twin was 48.6%; this rate was higher in MCDA twins (88.5%; RR, 1.824; 95% CI, 1.760-1.890) and more so in MCMA twins (100%; RR, 2.060; 95% CI, 2.000-2.121). In DC twins, the rate of preterm birth at < 32 weeks was 7.4%; this rate was higher in MCDA twins (14.2%; RR, 1.920; 95% CI, 1.616-2.281) and more so in MCMA twins (26.8%; RR, 3.637; 95% CI, 2.172-6.089). In DC twin pregnancies with at least one liveborn twin, the rate of a small-for-gestational-age neonate among all liveborn twins was 31.2% and in MCDA twins this rate was higher (37.8%; RR, 1.209; 95% CI, 1.138-1.284); in MCMA twins, the rate was not significantly different (33.3%; RR, 1.067; 95% CI, 0.783-1.455). Kaplan-Meier analysis showed a significant difference in survival in MCDA and MCMA twins, compared to DC twins, for both the interval of 12 to < 24 weeks' gestation (log-rank test, P < 0.0001 for both) and that of ≥ 24 to 38 weeks (log-rank test, P < 0.0001 for both). Endoscopic laser ablation of intertwin communicating placental vessels was carried out in 127 (10.0%) MCDA twin pregnancies for TTTS and/or sFGR and, in 111 of these, surgery was performed at < 24 weeks; both fetuses survived in 62 (55.9%) cases, one fetus survived in 25 (22.5%) cases and there were no survivors in 24 (21.6%) cases. On the extreme assumption that, had laser surgery not been carried out in these cases, all fetuses would have died, the total fetal loss rate at < 24 weeks' gestation in MCDA twins would have been 13.5%.

CONCLUSIONS

The rates of fetal loss at < 24 weeks' gestation, perinatal death at ≥ 24 weeks and preterm birth are higher in MCDA and more so in MCMA twins than in DC twins. In MCDA twins, the rate of fetal loss may have been reduced by endoscopic laser surgery in those that developed early TTTS and/or sFGR. These data would be useful in counseling parents as to the likely outcome of their pregnancy and in defining strategies for surveillance and interventions in the management of the different types of twin pregnancy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Value of routine ultrasound examination at 35-37 weeks' gestation in diagnosis of fetal abnormalities

OBJECTIVE

To investigate the potential value of routine ultrasound examination at 35-37 weeks' gestation in the diagnosis of previously unknown fetal abnormalities.

METHODS

This was a prospective study of 52 400 singleton pregnancies attending for a routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation; all pregnancies had a previous scan at 18-24 weeks and 47 214 also had a scan at 11-13 weeks. We included pregnancies resulting in live birth or stillbirth but excluded those with known chromosomal abnormality. Abnormalities were classified according to the affected major organ system, and the type and incidence of new abnormalities were determined.

RESULTS

In the study population, the incidence of fetal abnormality was 1.9% (995/52 400), including 674 (67.7%) that had been diagnosed previously during the first and/or second trimester, 247 (24.8%) that were detected for the first time at 35-37 weeks and 74 (7.4%) that were detected for the first time postnatally. The most common abnormalities that were diagnosed during the first and/or second trimester and that were also observed at 35-37 weeks included ventricular septal defect, talipes, unilateral renal agenesis and/or pelvic kidney, hydronephrosis, duplex kidney, unilateral multicystic kidney, congenital pulmonary airway malformation, ventriculomegaly, cleft lip and palate, polydactyly and abdominal cyst or gastroschisis. The most common abnormalities first seen at 35-37 weeks were hydronephrosis, mild ventriculomegaly, ventricular septal defect, duplex kidney, ovarian cyst and arachnoid cyst. The incidence of abnormalities first seen at 35-37 weeks was 0.5% and those that were detected exclusively for the first time at this examination were ovarian cyst, microcephaly, achondroplasia, dacryocystocele and hematocolpos. The incidence of abnormalities first seen postnatally was 0.1% and the most common were isolated cleft palate, polydactyly or syndactyly and ambiguous genitalia or hypospadias; prenatal examination of the genitalia was not a compulsory part of the protocol.

CONCLUSIONS

A high proportion of fetal abnormalities are detected for the first time during a routine ultrasound examination at 35-37 weeks' gestation. Such diagnosis and subsequent management, including selection of timing and place for delivery and postnatal investigations, could potentially improve postnatal outcome. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.