Diagnostic yield of exome sequencing in prenatal agenesis of corpus callosum: systematic review and meta-analysis.

OBJECTIVES: To determine the incremental diagnostic yield of exome sequencing (ES) after negative chromosomal microarray analysis (CMA) in cases of prenatally diagnosed agenesis of the corpus callosum (ACC) and to identify the associated genes and variants. METHODS: A systematic search was performed to identify relevant studies published up until June 2022 using four databases: PubMed, SCOPUS, Web of Science and The Cochrane Library. Studies in English reporting on the diagnostic yield of ES following negative CMA in prenatally diagnosed partial or complete ACC were included. Authors of cohort studies were contacted for individual participant data and extended cohorts were provided for two of them. The increase in diagnostic yield with ES for pathogenic/likely pathogenic (P/LP) variants was assessed in all cases of ACC, isolated ACC, ACC with other cranial anomalies and ACC with extracranial anomalies. To identify all reported genetic variants, the systematic review included all ACC cases; however, for the meta-analysis, only studies with ≥ three ACC cases were included. Meta-analysis of proportions was employed using a random-effects model. Quality assessment of the included studies was performed using modified Standards for Reporting of Diagnostic Accuracy criteria. RESULTS: A total of 28 studies, encompassing 288 prenatally diagnosed ACC cases that underwent ES following negative CMA, met the inclusion criteria of the systematic review. We classified 116 genetic variants in 83 genes associated with prenatal ACC with a full phenotypic description. There were 15 studies, encompassing 268 cases, that reported on ≥ three ACC cases and were included in the meta-analysis. Of all the included cases, 43% had a P/LP variant on ES. The highest yield was for ACC with extracranial anomalies (55% (95% CI, 35-73%)), followed by ACC with other cranial anomalies (43% (95% CI, 30-57%)) and isolated ACC (32% (95% CI, 18-51%)). CONCLUSIONS: ES demonstrated an incremental diagnostic yield in cases of prenatally diagnosed ACC following negative CMA. While the greatest diagnostic yield was observed in ACC with extracranial anomalies and ACC with other central nervous system anomalies, ES should also be considered in cases of isolated ACC. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Fetal exome sequencing for isolated increased nuchal translucency: should we be doing it?

OBJECTIVE: To evaluate the utility of prenatal exome sequencing (ES) for isolated increased nuchal translucency (NT) and to investigate factors that increase diagnostic yield. DESIGN: Retrospective analysis of data from two prospective cohort studies. SETTING: Fetal medicine centres in the UK and USA. POPULATION: Fetuses with increased NT ≥3.5 mm at 11-14 weeks of gestation recruited to the Prenatal Assessment of Genomes and Exomes (PAGE) and Columbia fetal whole exome sequencing studies (n = 213). METHODS: We grouped cases based on (1) the presence of additional structural abnormalities at presentation in the first trimester or later in pregnancy, and (2) NT measurement at presentation. We compared diagnostic rates between groups using Fisher exact test. MAIN OUTCOME MEASURES: Detection of diagnostic genetic variants considered to have caused the observed fetal structural anomaly. RESULTS: Diagnostic variants were detected in 12 (22.2%) of 54 fetuses presenting with non-isolated increased NT, 12 (32.4%) of 37 fetuses with isolated increased NT in the first trimester and additional abnormalities later in pregnancy, and 2 (1.8%) of 111 fetuses with isolated increased NT in the first trimester and no other abnormalities on subsequent scans. Diagnostic rate also increased with increasing size of NT. CONCLUSIONS: The diagnostic yield of prenatal ES is low for fetuses with isolated increased NT but significantly higher where there are additional structural anomalies. Prenatal ES may not be appropriate for truly isolated increased NT but timely, careful ultrasound scanning to identify other anomalies emerging later can direct testing to focus where there is a higher likelihood of diagnosis.

Fetal hydrops and the Incremental yield of Next-generation sequencing over standard prenatal Diagnostic testing (FIND) study: prospective cohort study and meta-analysis.

OBJECTIVE: To determine the incremental yield of exome sequencing (ES) over chromosomal microarray analysis (CMA) or karyotyping in prenatally diagnosed non-immune hydrops fetalis (NIHF). METHODS: A prospective cohort study (comprising an extended group of the Prenatal Assessment of Genomes and Exomes (PAGE) study) was performed which included 28 cases of prenatally diagnosed NIHF undergoing trio ES following negative CMA or karyotyping. These cases were combined with data from a systematic review of the literature. MEDLINE, EMBASE, CINAHL and ClinicalTrials.gov databases were searched electronically (January 2000 to October 2020) for studies reporting on the incremental yield of ES over CMA or karyotyping in fetuses with prenatally detected NIHF. Inclusion criteria for the systematic review were: (i) at least two cases of NIHF undergoing sequencing; (ii) testing initiated based on prenatal ultrasound-based phenotype; and (iii) negative CMA or karyotyping result. The incremental diagnostic yield of ES was assessed in: (i) all cases of NIHF; (ii) isolated NIHF; (iii) NIHF associated with an additional fetal structural anomaly; and (iv) NIHF according to severity (i.e. two vs three or more cavities affected). RESULTS: In the extended PAGE study cohort, the additional diagnostic yield of ES over CMA or karyotyping was 25.0% (7/28) in all NIHF cases, 21.4% (3/14) in those with isolated NIHF and 28.6% (4/14) in those with non-isolated NIHF. In the meta-analysis, the pooled incremental yield based on 21 studies (306 cases) was 29% (95% CI, 24-34%; P < 0.00001; I2 = 0%) in all NIHF, 21% (95% CI, 13-30%; P < 0.00001; I2 = 0%) in isolated NIHF and 39% (95% CI, 30-49%; P < 0.00001; I2 = 1%) in NIHF associated with an additional fetal structural anomaly. In the latter group, congenital limb contractures were the most prevalent additional structural anomaly associated with a causative pathogenic variant, occurring in 17.3% (19/110) of cases. The incremental yield did not differ significantly according to hydrops severity. The most common genetic disorders identified were RASopathies, occurring in 30.3% (27/89) of cases with a causative pathogenic variant, most frequently due to a PTPN11 variant (44.4%; 12/27). The predominant inheritance pattern in causative pathogenic variants was autosomal dominant in monoallelic disease genes (57.3%; 51/89), with most being de novo (86.3%; 44/51). CONCLUSIONS: Use of prenatal next-generation sequencing in both isolated and non-isolated NIHF should be considered in the development of clinical pathways. Given the wide range of potential syndromic diagnoses and heterogeneity in the prenatal phenotype of NIHF, exome or whole-genome sequencing may prove to be a more appropriate testing approach than a targeted gene panel testing strategy. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

COngenital heart disease and the Diagnostic yield with Exome sequencing (CODE) study: prospective cohort study and systematic review.

OBJECTIVE: To determine the incremental yield of antenatal exome sequencing (ES) over chromosomal microarray analysis (CMA) or conventional karyotyping in prenatally diagnosed congenital heart disease (CHD). METHODS: A prospective cohort study of 197 trios undergoing ES following CMA or karyotyping owing to CHD identified prenatally and a systematic review of the literature were performed. MEDLINE, EMBASE, CINAHL and ClinicalTrials.gov (January 2000 to October 2019) databases were searched electronically for studies reporting on the diagnostic yield of ES in prenatally diagnosed CHD. Selected studies included those with more than three cases, with initiation of testing based upon prenatal phenotype only and that included cases in which CMA or karyotyping was negative. The incremental diagnostic yield of ES was assessed in: (1) all cases of CHD; (2) isolated CHD; (3) CHD associated with extracardiac anomaly (ECA); and (4) CHD according to phenotypic subgroup. RESULTS: In our cohort, ES had an additional diagnostic yield in all CHD, isolated CHD and CHD associated with ECA of 12.7% (25/197), 11.5% (14/122) and 14.7% (11/75), respectively (P = 0.81). The corresponding pooled incremental yields from 18 studies (encompassing 636 CHD cases) included in the systematic review were 21% (95% CI, 15-27%), 11% (95% CI, 7-15%) and 37% (95% CI, 18-56%), respectively. The results did not differ significantly when subanalysis was limited to studies including more than 20 cases, except for CHD associated with ECA, in which the incremental yield was greater (49% (95% CI, 17-80%)). In cases of CHD associated with ECA in the primary analysis, the most common extracardiac anomalies associated with a pathogenic variant were those affecting the genitourinary system (23/52 (44.2%)). The greatest incremental yield was in cardiac shunt lesions (41% (95% CI, 19-63%)), followed by right-sided lesions (26% (95% CI, 9-43%)). In the majority (68/96 (70.8%)) of instances, pathogenic variants occurred de novo and in autosomal dominant (monoallelic) disease genes. The most common (19/96 (19.8%)) monogenic syndrome identified was Kabuki syndrome. CONCLUSIONS: There is an apparent incremental yield of prenatal ES in CHD. While the greatest yield is in CHD associated with ECA, consideration could also be given to performing ES in the presence of an isolated cardiac abnormality. A policy of routine application of ES would require the adoption of robust bioinformatic, clinical and ethical pathways. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

Cervical funneling or intra-amniotic debris and preterm birth in nulliparous women with midtrimester cervical length less than 30 mm.

OBJECTIVE: To evaluate whether the presence of cervical funneling or intra-amniotic debris identified in the second trimester is associated with a higher rate of preterm birth (PTB) in asymptomatic nulliparous pregnant women with a midtrimester cervical length (CL) less than 30 mm (i.e. below the 10th percentile). METHODS: This was a secondary cohort analysis of data from a multicenter trial in nulliparous women between 16 and 22 weeks' gestation with a singleton gestation and CL less than 30 mm on transvaginal ultrasound, randomized to treatment with either 17-alpha-hydroxyprogesterone caproate or placebo. Sonographers were centrally certified in CL measurement, as well as in identification of intra-amniotic debris and cervical funneling. Univariable and multivariable analysis was performed to assess the associations of cervical funneling and intra-amniotic debris with PTB. RESULTS: Of the 657 women randomized, 112 (17%) had cervical funneling only, 33 (5%) had intra-amniotic debris only and 45 (7%) had both on second-trimester ultrasound. Women with either of these findings had a shorter median CL than those without (21.0 mm vs 26.4 mm; P < 0.001). PTB prior to 37 weeks was more likely in women with cervical funneling (37% vs 21%; odds ratio (OR), 2.2 (95% CI, 1.5-3.3)) or intra-amniotic debris (35% vs 23%; OR, 1.7 (95% CI, 1.1-2.9)). Results were similar for PTB before 34 and before 32 weeks' gestation. After multivariable adjustment that included CL, PTB < 34 and < 32 weeks continued to be associated with the presence of intra-amniotic debris (adjusted OR (aOR), 1.85 (95% CI, 1.00-3.44) and aOR, 2.78 (95% CI, 1.42-5.45), respectively), but not cervical funneling (aOR, 1.17 (95% CI, 0.63-2.17) and aOR, 1.45 (95% CI, 0.71-2.96), respectively). CONCLUSIONS: Among asymptomatic nulliparous women with midtrimester CL less than 30 mm, the presence of intra-amniotic debris, but not cervical funneling, is associated with an increased risk for PTB before 34 and 32 weeks' gestation, independently of CL. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Serious maternal complications in relation to severe pre-eclampsia: a retrospective cohort study of the impact of hospital volume.

OBJECTIVE: We examined rates of serious maternal complications in relation to severe pre-eclampsia based on the delivering hospital's annualised volume. DESIGN: Retrospective cohort study. POPULATION AND SETTING: Singleton deliveries (n = 25 782 235) in 439 hospitals in the USA. METHODS: Annualised hospital volume was categorised as 25-500, 501-1000, 1001-2000 and >2000. MAIN OUTCOME MEASURES: Rates of in-hospital maternal death and serious maternal complications, including puerperal cerebrovascular disorders, pulmonary oedema, disseminated intravascular coagulation, acute renal, heart and liver failure, sepsis, haemorrhage and intubation in relation to severe pre-eclampsia. We derived adjusted risk ratio (RR) and 95% confidence interval (CI), from hierarchical Poisson regression models. RESULTS: Severe pre-eclampsia was associated with an 8.7-fold (95% CI 7.6, 10.1) risk of composite maternal complications, with similar RRs across levels of hospital volumes. However, compared with hospitals with low annual volume (<2000), maternal mortality rates in relation to severe pre-eclampsia were lower in high volume hospitals. The rates of serious maternal complications were 410.7 per 10 000 to women who delivered in hospitals with a high rate of severe pre-eclampsia (≥2.12%) and 584.8 per 10 000 to women who delivered in hospitals with low severe pre-eclampsia rates (≤0.41; RR 1.75, 95% CI 1.24, 2.45). CONCLUSIONS: While the risks of serious maternal complications in relation to severe pre-eclampsia was similar across hospital delivery volume categories, deaths showed lower rates in large delivery volume hospitals than in smaller volume hospitals. The risk of complications was increased in hospitals with low compared with high severe pre-eclampsia rates. TWEETABLE ABSTRACT: Hospital volume had little impact on the association between severe pre-eclampsia and maternal complications.

Neonatal Genetic Variation in Steroid Metabolism and Key Respiratory Function Genes and Perinatal Outcomes in Single and Multiple Courses of Corticosteroids.

OBJECTIVE: The aim of the study is to evaluate the association of steroid metabolism and respiratory gene polymorphisms in neonates exposed to antenatal corticosteroids (ACS) with respiratory outcomes, small for gestational age (SGA), and response to repeat ACS. STUDY DESIGN: This candidate gene study is a secondary analysis of women enrolled in a randomized controlled trial of single versus weekly courses of ACS. Nineteen single nucleotide polymorphisms (SNPs) in 13 steroid metabolism and respiratory function genes were evaluated. DNA was extracted from placenta or fetal cord serum and analyzed with TaqMan genotyping. Each SNP was evaluated for association via logistic regression with respiratory distress syndrome (RDS), continuous positive airway pressure (CPAP)/ventilator use (CPV), and SGA. RESULTS: CRHBP, CRH, and CRHR1 minor alleles were associated with an increased risk of SGA. HSD11B1 and SCNN1B minor alleles were associated with an increased likelihood of RDS. Carriage of minor alleles in SerpinA6 was associated with an increased risk of CPV. CRH and CRHR1 minor alleles were associated with a decreased likelihood of CPV. CONCLUSION: Steroid metabolism and respiratory gene SNPs are associated with respiratory outcomes and SGA in patients exposed to ACS. Risks for respiratory outcomes are affected by minor allele carriage as well as by treatment with multiple ACS.

Prenatal vitamin C and E supplementation in smokers is associated with reduced placental abruption and preterm birth: a secondary analysis.

OBJECTIVE: Smoking and pre-eclampsia (PE) are associated with increases in preterm birth, placental abruption and low birthweight. We evaluated the relationship between prenatal vitamin C and E (C/E) supplementation and perinatal outcomes by maternal self-reported smoking status focusing on outcomes known to be impacted by maternal smoking. DESIGN/SETTING/POPULATION: A secondary analysis of a multi-centre trial of vitamin C/E supplementation starting at 9-16 weeks in low-risk nulliparous women with singleton gestations. METHODS: We examined the effect of vitamin C/E by smoking status at randomisation using the Breslow-Day test for interaction. MAIN OUTCOME MEASURES: The trial's primary outcomes were PE and a composite outcome of pregnancy-associated hypertension (PAH) with serious adverse outcomes. Perinatal outcomes included preterm birth and abruption. RESULTS: There were no differences in baseline characteristics within subgroups (smokers versus nonsmokers) by vitamin supplementation status. The effect of prenatal vitamin C/E on the risk of PE (P = 0.66) or PAH composite outcome (P = 0.86) did not differ by smoking status. Vitamin C/E was protective for placental abruption in smokers (relative risk [RR] 0.09; 95% CI 0.00-0.87], but not in nonsmokers (RR 0.92; 95% CI 0.52-1.62) (P = 0.01), and for preterm birth in smokers (RR 0.76; 95% CI 0.58-0.99) but not in nonsmokers (RR 1.03; 95% CI 0.90-1.17) (P = 0.046). CONCLUSION: In this cohort of women, smoking was not associated with a reduction in PE or the composite outcome of PAH. Vitamin C/E supplementation appears to be associated with a reduction in placental abruption and preterm birth among smokers.

Use of prenatal chromosomal microarray: prospective cohort study and systematic review and meta-analysis.

OBJECTIVES: Chromosomal microarray analysis (CMA) is utilized in prenatal diagnosis to detect chromosomal abnormalities not visible by conventional karyotyping. A prospective cohort of women undergoing fetal CMA and karyotyping following abnormal prenatal ultrasound findings is presented in the context of a systematic review and meta-analysis of the literature describing detection rates by CMA and karyotyping. METHODS: We performed a prospective cohort study of 243 women undergoing CMA alongside karyotyping when a structural abnormality was detected on prenatal ultrasound. A systematic review of the literature was also performed. MEDLINE (1970-Dec 2012), EMBASE (1980-Dec 2012) and CINAHL (1982-June 2012) databases were searched electronically. Selected studies included > 10 cases and prenatal CMA in addition to karyotyping. The search yielded 560 citations. Full papers were retrieved for 86, and 25 primary studies were included in the systematic review. RESULTS: Our cohort study found an excess detection rate of abnormalities by CMA of 4.1% over conventional karyotyping when the clinical indication for testing was an abnormal fetal ultrasound finding; this was lower than the detection rate of 10% (95% CI, 8-13%) by meta-analysis. The rate of detection for variants of unknown significance (VOUS) was 2.1% (95% CI, 1.3-3.3%) when the indication for CMA was an abnormal scan finding. The VOUS detection rate was lower (1.4%; 95% CI, 0.5-3.7%) when any indication for prenatal CMA was meta-analyzed. CONCLUSION: We present evidence for a higher detection rate by CMA than by karyotyping not just in the case of abnormal ultrasound findings but also in cases of other indications for invasive testing. It is likely that CMA will replace karyotyping in high-risk pregnancies.

Can changes in angiogenic biomarkers between the first and second trimesters of pregnancy predict development of pre-eclampsia in a low-risk nulliparous patient population?

OBJECTIVE: To determine if change in maternal angiogenic biomarkers between the first and second trimesters predicts pre-eclampsia in low-risk nulliparous women. DESIGN: A nested case-control study of change in maternal plasma soluble Flt-1 (sFlt-1), soluble endoglin (sEng) and placenta growth factor (PlGF). We studied 158 pregnancies complicated by pre-eclampsia and 468 normotensive nonproteinuric controls. SETTING: A multicentre study in 16 academic medical centres in the USA. POPULATION: Low-risk nulliparous women. METHODS: Luminex assays for PlGF, sFlt-1 and sEng performed on maternal EDTA plasma collected at 9-12, 15-18 and 23-26 weeks of gestation. Rate of change of analyte between first and either early or late second trimester was calculated with and without adjustment for baseline clinical characteristics. MAIN OUTCOME MEASURES: Change in PlGF, sFlt-1 and sEng. RESULTS: Rates of change of PlGF, sEng and sFlt-1 between first and either early or late second trimesters were significantly different in women who developed pre-eclampsia, severe pre-eclampsia or early-onset pre-eclampsia compared with women who remained normotensive. Inclusion of clinical characteristics (race, body mass index and blood pressure at entry) increased sensitivity for detecting severe and particularly early-onset pre-eclampsia but not pre-eclampsia overall. Receiver operating characteristics curves for change from first to early second trimester in sEng, PlGF and sFlt-1 with clinical characteristics had areas under the curve of 0.88, 0.84 and 0.86, respectively, and for early-onset pre-eclampsia with sensitivities of 88% (95% CI 64-99), 77% (95% CI 50-93) and 77% (95% CI 50-93) for 80% specificity, respectively. Similar results were seen in the change from first to late second trimester. CONCLUSION: Change in angiogenic biomarkers between first and early second trimester combined with clinical characteristics has strong utility for predicting early-onset pre-eclampsia.

Vitamin D status and recurrent preterm birth: a nested case-control study in high-risk women.

OBJECTIVE: To determine whether vitamin D status is associated with recurrent preterm birth, and any interactions between vitamin D levels and fish consumption. DESIGN: A nested case-control study, using data from a randomised trial of omega-3 fatty acid supplementation to prevent recurrent preterm birth. SETTING: Fourteen academic health centres in the USA. POPULATION: Women with prior spontaneous preterm birth. METHODS: In 131 cases (preterm delivery at <35 weeks of gestation) and 134 term controls, we measured serum 25-hydroxyvitamin D [25(OH)D] concentrations by liquid chromatography-tandem mass spectrometry (LC-MS) from samples collected at baseline (16-22 weeks of gestation). Logistic regression models controlled for study centre, maternal age, race/ethnicity, number of prior preterm deliveries, smoking status, body mass index, and treatment. MAIN OUTCOME MEASURES: Recurrent preterm birth at <37 and <32 weeks of gestation. RESULTS: The median mid-gestation serum 25(OH)D concentration was 67 nmol/l, and 27% had concentrations of <50 nmol/l. Serum 25(OH)D concentration was not significantly associated with preterm birth (OR 1.33; 95% CI 0.48-3.70 for lowest versus highest quartiles). Likewise, comparing women with 25(OH)D concentrations of 50 nmol/l, or higher, with those with <50 nmol/l generated an odds ratio of 0.80 (95% CI 0.38-1.69). Contrary to our expectation, a negative correlation was observed between fish consumption and serum 25(OH)D concentration (-0.18, P < 0.01). CONCLUSIONS: In a cohort of women with a prior preterm birth, vitamin D status at mid-pregnancy was not associated with recurrent preterm birth.

Late first-trimester invasive prenatal diagnosis: results of an international randomized trial.

OBJECTIVE: To assess, in a randomized trial, the safety and accuracy of amniocentesis and transabdominal chorionic villus sampling (CVS) performed at 11-14 weeks of gestation, given that this time frame is increasingly relevant to early trisomy screening. METHODS: We compared amniocentesis with CVS from 77 to 104 days of gestation in a randomized trial in a predominantly advanced maternal age population. Before randomization, the feasibility of both procedures was confirmed by ultrasonography, and experienced operators performed sampling under ultrasound guidance; conventional cytogenetic analysis was employed. The primary outcome measure was a composite of fetal loss plus preterm delivery before 28 weeks of gestation in cytogenetically normal pregnancies. RESULTS: We randomized 3,775 women into 2 groups (1,914 to CVS; 1,861 to amniocentesis), which were comparable at baseline. More than 99.6% had the assigned procedure, and 99.9% were followed through delivery. In contrast to previous thinking, in the cytogenetically normal cohort (n = 3,698), no difference in primary study outcome was observed: 2.1% (95% confidence interval 1.5, 2.8) for CVS and 2.3% (95% confidence interval, 1.7, 3.1) for amniocentesis. However, spontaneous losses before 20 weeks and procedure-related, indicated terminations combined were increased in the amniocentesis group (P =.07, relative risk 1.74). We found a 4-fold increase in the rate of talipes equinovarus after amniocentesis (P =.02) overall and in week 13 (P =.03, relative risk = 4.65), but data were insufficient to determine this risk in week 14. CONCLUSION: Amniocentesis at 13 weeks carries a significantly increased risk of talipes equinovarus compared with CVS and also suggests an increase in early, unintended pregnancy loss. LEVEL OF EVIDENCE: I

Fetal gender and aneuploidy detection using fetal cells in maternal blood: analysis of NIFTY I data. National Institute of Child Health and Development Fetal Cell Isolation Study.

OBJECTIVES: The National Institute of Child Health and Human Development Fetal Cell Isolation Study (NIFTY) is a prospective, multicenter clinical project to develop non-invasive methods of prenatal diagnosis. The initial objective was to assess the utility of fetal cells in the peripheral blood of pregnant women to diagnose or screen for fetal chromosome abnormalities. METHODS: Results of fluorescence in situ hybridization (FISH) analysis on interphase nuclei of fetal cells recovered from maternal blood were compared to metaphase karyotypes of fetal cells obtained by amniocentesis or chorionic villus sampling (CVS). After the first 5 years of the study we performed a planned analysis of the data. We report here the data from 2744 fully processed pre-procedural blood samples; 1292 samples were from women carrying singleton male fetuses. RESULTS: Target cell recovery and fetal cell detection were better using magnetic-based separation systems (MACS) than with flow-sorting (FACS). Blinded FISH assessment of samples from women carrying singleton male fetuses found at least one cell with an X and Y signal in 41.4% of cases (95% CI: 37.4%, 45.5%). The false-positive rate of gender detection was 11.1% (95% CI: 6.1,16.1%). This was higher than expected due to the use of indirectly labeled FISH probes in one center. The detection rate of finding at least one aneuploid cell in cases of fetal aneuploidy was 74.4% (95% CI: 76.0%, 99.0%), with a false-positive rate estimated to be between 0.6% and 4.1%. CONCLUSIONS: The sensitivity of aneuploidy detection using fetal cell analysis from maternal blood is comparable to single marker prenatal serum screening, but technological advances are needed before fetal cell analysis has clinical application as part of a multiple marker method for non-invasive prenatal screening. The limitations of the present study, i.e. multiple processing protocols, are being addressed in the ongoing study.

First-trimester trisomy screening: nuchal translucency measurement training and quality assurance to correct and unify technique.

OBJECTIVE: To describe the process of training for measuring nuchal translucency at five clinical centers in North America and to evaluate methods of quality assurance and feedback. DESIGN: Throughout a period of 18 months, the performance of sonographers in measuring fetal nuchal translucency was monitored using qualitative and quantitative methods of review. After 12 months, different approaches (written and personal feedback) were used to inform sonographers of technical aspects that needed to or could be improved. RESULTS: On initial qualitative review, discrepancies in judgment from different reviewers coincided with suboptimal magnification, failure to visualize the amniotic membrane and/or use of cross-shaped calipers. At subsequent global review, 13 (29%) images of nuchal translucency measurements were considered unacceptable. Quantitative assessment revealed that, during the first part of the study, the means from four sonographers were significantly smaller and the mean from the fifth sonographer was significantly larger than expected on the basis of findings from The Fetal Medicine Foundation (P < 0.0001). Following feedback, sonographers who underestimated nuchal translucency and who received a written report only did not change measurements overall (P = 0.9759). In contrast, those who received additional intervention showed a marked difference (P < 0.0001). CONCLUSIONS: Global qualitative review of images from one sonographer may be preferable to assessment of individual aspects of images. Results from global qualitative review correspond well with findings from quantitative analysis, indicating that the latter can be applied for ongoing audit. Observation of divergent results should prompt extensive personal feedback, rather than a written report, to prevent sonographers from settling in their own, inappropriate technique.

Accuracy of prenatal diagnosis of congenital heart defects.

OBJECTIVES: (1) To evaluate the detection and accuracy of fetal echocardiography for congenital heart defects (CHD). (2) To compare the detection and accuracy of a team of maternal fetal medicine specialists and radiologists (MFM/R) with those of perinatal cardiologists (PC). METHODS: All fetal echocardiograms performed from 1/91 to 6/95 were reviewed retrospectively. CHD diagnoses made prenatally were compared with postnatally-confirmed diagnoses. RESULTS: 106 heat defects were correctly detected prenatally. There were 10 incorrect diagnoses, 6 false-negatives and 4 false-positives. Overall detection rate (sensitivity) was 95%, while overall accuracy was 87%. Detection rate for MFM/R and PC were 91 and 97%, respectively (p = 0.4). Accuracy was 74% for MFM/R and 92% for PC (p = 0.02). CONCLUSIONS: CHD can be identified reliably by prenatal echocardiography. The involvement of a PC in the prenatal diagnosis of these defects may improve diagnostic accuracy.

In vitro sealing of punctured fetal membranes: potential treatment for midtrimester premature rupture of membranes.

OBJECTIVE: Midtrimester premature rupture of membranes causes significant perinatal morbidity and death. No effective treatment exists. We investigated (1) whether a needle puncture in the fetal membranes could be sealed in vitro and (2) the optimal composition of the sealant to be used. STUDY DESIGN: Membranes from second trimester pregnancies (16-24 weeks of gestation) were stretched over a modified syringe with a 2.5-cm open diameter. The syringe was filled with 20 mL of second trimester amniotic fluid, and the membrane was punctured with a 20-gauge needle. Sealants were injected into the amniotic fluid. The primary outcome variable was time for leakage of amniotic fluid. Median times for leakage for the formulations were compared by Wilcoxon exact rank sum test. RESULTS: Platelets alone failed to seal the puncture site. All other formulations stopped leakage temporarily. Tisseel (Baxter Corp, Glendale, Calif) and cryoprecipitate/thrombin preparations led to more prolonged sealing of punctured amniotic membranes than platelets (P <.01) and were not significantly different from each other. CONCLUSION: Of the sealants tested in vitro, amniotic membranes are best sealed by a fibrin/thrombin-based sealant.

Does transvaginal ultrasound of the cervix predict preterm premature rupture of membranes in a high-risk population?

OBJECTIVES: To determine in patients with a cervical length < 25 mm on transvaginal ultrasound if the severity of cervical length shortening can be used to predict preterm premature rupture of membranes (PPROM) and the contribution of PPROM to preterm delivery in these patients. METHODS: We retrospectively reviewed asymptomatic singleton pregnancies between 14 and 24 weeks at high risk of preterm delivery by obstetric history and transvaginal cervical length < 25 mm. Cases developing subsequent PPROM were compared with controls for transvaginal sonographic cervical characteristics. RESULTS: Of 69 patients identified to have a cervical length < 25 mm, 27 (39%) had PPROM, and 42 (61%) did not. Mean +/- standard deviation (SD) cervical length was 12.7 +/- 8.7 mm and 17.0 +/- 7.6 mm in the two groups, respectively (P = 0.04). Mean +/- SD cervical funneling was 57.4 +/- 31.4% and 40.0 +/- 28.1%, respectively (P = 0.01). The characteristics most predictive of PPROM were: cervical length of < 10 mm (sensitivity, specificity, positive and negative predictive values of 33, 90, 69, and 68%, respectively; odds ratio, 4.8; 95% confidence interval, 1.3-17.5) and cervical funneling > 75% (sensitivity, specificity, positive and negative predictive values of 33, 93, 75 and 68%, respectively; odds ratio, 6.5; 95% confidence interval, 1.6-26.9). Stepwise logistic regression revealed cervical length to be a significant predictor of PPROM (odds ratio, 4.0; 95% confidence interval, 1.1-14.2). CONCLUSION: In patients at high risk for preterm delivery because of obstetric history and transvaginal sonographic cervical length < 25 mm, a cervical length < 10 mm and cervical funneling > 75% were most predictive of PPROM. PPROM was the major contributor to preterm delivery in these patients.