How often do we incidentally find a fetal abnormality at the routine third-trimester growth scan? A population-based study

Diagnostic accuracy of ultrasound screening for fetal structural abnormalities during the first and second trimester of pregnancy in low-risk and unselected populations

BACKGROUND

Prenatal ultrasound is widely used to screen for structural anomalies before birth. While this is traditionally done in the second trimester, there is an increasing use of first-trimester ultrasound for early detection of lethal and certain severe structural anomalies.

OBJECTIVES

To evaluate the diagnostic accuracy of ultrasound in detecting fetal structural anomalies before 14 and 24 weeks' gestation in low-risk and unselected pregnant women and to compare the current two main prenatal screening approaches: a single second-trimester scan (single-stage screening) and a first- and second-trimester scan combined (two-stage screening) in terms of anomaly detection before 24 weeks' gestation.

SEARCH METHODS

We searched MEDLINE, EMBASE, Science Citation Index Expanded (Web of Science), Social Sciences Citation Index (Web of Science), Arts & Humanities Citation Index and Emerging Sources Citation Index (Web of Science) from 1 January 1997 to 22 July 2022. We limited our search to studies published after 1997 and excluded animal studies, reviews and case reports. No further restrictions were applied. We also screened reference lists and citing articles of each of the included studies.

SELECTION CRITERIA

Studies were eligible if they included low-risk or unselected pregnant women undergoing a first- and/or second-trimester fetal anomaly scan, conducted at 11 to 14 or 18 to 24 weeks' gestation, respectively. The reference standard was detection of anomalies at birth or postmortem.

DATA COLLECTION AND ANALYSIS

Two review authors independently undertook study selection, quality assessment (QUADAS-2), data extraction and evaluation of the certainty of evidence (GRADE approach). We used univariate random-effects logistic regression models for the meta-analysis of sensitivity and specificity.

MAIN RESULTS

Eighty-seven studies covering 7,057,859 fetuses (including 25,202 with structural anomalies) were included. No study was deemed low risk across all QUADAS-2 domains. Main methodological concerns included risk of bias in the reference standard domain and risk of partial verification. Applicability concerns were common in studies evaluating first-trimester scans and two-stage screening in terms of patient selection due to frequent recruitment from single tertiary centres without exclusion of referrals. We reported ultrasound accuracy for fetal structural anomalies overall, by severity, affected organ system and for 46 specific anomalies. Detection rates varied widely across categories, with the highest estimates of sensitivity for thoracic and abdominal wall anomalies and the lowest for gastrointestinal anomalies across all tests. The summary sensitivity of a first-trimester scan was 37.5% for detection of structural anomalies overall (95% confidence interval (CI) 31.1 to 44.3; low-certainty evidence) and 91.3% for lethal anomalies (95% CI 83.9 to 95.5; moderate-certainty evidence), with an overall specificity of 99.9% (95% CI 99.9 to 100; low-certainty evidence). Two-stage screening had a combined sensitivity of 83.8% (95% CI 74.7 to 90.1; low-certainty evidence), while single-stage screening had a sensitivity of 50.5% (95% CI 38.5 to 62.4; very low-certainty evidence). The specificity of two-stage screening was 99.9% (95% CI 99.7 to 100; low-certainty evidence) and for single-stage screening, it was 99.8% (95% CI 99.2 to 100; moderate-certainty evidence). Indirect comparisons suggested superiority of two-stage screening across all analyses regarding sensitivity, with no significant difference in specificity. However, the certainty of the evidence is very low due to the absence of direct comparisons.

AUTHORS' CONCLUSIONS

A first-trimester scan has the potential to detect lethal and certain severe anomalies with high accuracy before 14 weeks' gestation, despite its limited overall sensitivity. Conversely, two-stage screening shows high accuracy in detecting most fetal structural anomalies before 24 weeks' gestation with high sensitivity and specificity. In a hypothetical cohort of 100,000 fetuses, the first-trimester scan is expected to correctly identify 113 out of 124 fetuses with lethal anomalies (91.3%) and 665 out of 1776 fetuses with any anomaly (37.5%). However, 79 false-positive diagnoses are anticipated among 98,224 fetuses (0.08%). Two-stage screening is expected to correctly identify 1448 out of 1776 cases of structural anomalies overall (83.8%), with 118 false positives (0.1%). In contrast, single-stage screening is expected to correctly identify 896 out of 1776 cases before 24 weeks' gestation (50.5%), with 205 false-positive diagnoses (0.2%). This represents a difference of 592 fewer correct identifications and 88 more false positives compared to two-stage screening. However, it is crucial to acknowledge the uncertainty surrounding the additional benefits of two-stage versus single-stage screening, as there are no studies directly comparing them. Moreover, the evidence supporting the accuracy of first-trimester ultrasound and two-stage screening approaches primarily originates from studies conducted in single tertiary care facilities, which restricts the generalisability of the results of this meta-analysis to the broader population.

The Diagnostic Yield of Chromosomal Microarray Analysis in Third-Trimester Fetal Abnormalities

OBJECTIVE

 This study aimed to determine the diagnostic yield of chromosomal microarray analysis (CMA) performed in cases of fetal abnormalities detected during the third trimester of pregnancy.

STUDY DESIGN

 A retrospective review of medical records was conducted for women who underwent amniocentesis at or beyond 28 weeks of gestation between January 2017 and February 2023. CMA results of pregnancies with abnormal sonographic findings not detected before 28 weeks were included.

RESULTS

 A total of 482 fetuses met the inclusion criteria. The average maternal age was 31.3 years, and the average gestational age at amniocentesis was 32.3 weeks. The overall diagnostic yield of CMA was 6.2% (30 clinically significant copy number variations [CNVs]). The yield was 16.4% in cases with two or more fetal malformations, while cases with a single anomaly revealed a diagnostic yield of 7.3%. Cases presenting isolated polyhydramnios or isolated fetal growth restriction had a lower yield of 9.3 and 5.4%, respectively. Of the 30 clinically significant cases, 19 (or 63.4%) exhibited recurrent CNVs. The remaining 11 cases (or 36.6%) presented unique CNVs. The theoretical yield of Noninvasive Prenatal Testing (NIPT) in our cohort is 2% for aneuploidy, which implies that it could potentially miss up to 70% of the significant findings that could be identified by CMA. In 80% of the fetuses (or 24 out of 30) with clinically significant CNVs, the structural abnormalities detected on fetal ultrasound examinations corresponded with the CMA results.

CONCLUSION

 The 6.2% detection rate of significant CNVs in late-onset fetal anomalies confirms the value of CMA in third-trimester amniocentesis. The findings underscore the necessity of CMA for detecting CNVs potentially overlooked by NIPT and emphasize the importance of thorough genetic counseling.

KEY POINTS

· CMA yields 6.2% for third-trimester anomalies.. · NIPT may miss 70% of CMA findings.. · Ultrasound matched 80% of CMA results..

Postnatal diagnosis of congenital anomalies despite active systematic prenatal screening policies: a population-based registry study

BACKGROUND

Prenatal screening for congenital anomalies is an important component of maternity care, with continual advances in screening technology. However, few recent studies have investigated the overall effectiveness of a systematic policy of prenatal screening for congenital anomalies, such as in France where an ultrasound per trimester is recommended for all pregnant individuals.

OBJECTIVE

This study aimed to assess the proportion and the type of congenital anomalies that are not detected during pregnancy.

STUDY DESIGN

The study population included all singleton fetuses and newborns with congenital anomalies from the Paris Registry of Congenital Malformations (remaPAR) from 2001 to 2021. The registry includes all live births and stillbirths at ≥22 weeks of gestation and terminations of pregnancy for fetal anomaly at any gestational age with congenital anomalies diagnosed from the prenatal period until discharge home from hospital after birth. The prevalence of postnatally detected congenital anomalies was estimated overall and for 5-year intervals within the study period. We also reported the proportion of postnatal detection by subgroups of congenital anomalies according to the EUROCAT classification.

RESULTS

Of the 16,602 malformed singleton fetuses and newborns, 32.7% were detected postnatally. Of those with severe anomalies, 11.9% were detected postnatally. The postnatal detection rate decreased from 34.3% from 2001 to 2005, to 27.8% from 2016 to 2021 (P<.001). Anomalies most frequently detected postnatally were genital anomalies (n=969; 87.0%), followed by ear, neck, and face anomalies (n=71; 78.0%), eye anomalies (n=154; 74.0%), and limb anomalies (n=1802; 68.4%). Anomalies of the kidneys and the urinary tract (n=219; 7.1%) and the abdominal wall (n=37; 8.7%) were least likely to be detected after birth. Among the anomalies classified as severe, postnatal detection rates were highest for limb reduction defects (n=142; 40.6%), complete transposition of the great arteries (n=31; 17.6%), and diaphragmatic hernia (n=26; 17.2%).

CONCLUSION

Despite improvement of prenatal screening over a 20-year period, our results show that there is still a margin for improvement in prenatal diagnosis of congenital anomalies.

A Novel Framework for Abnormal Risk Classification over Fetal Nuchal Translucency Using Adaptive Stochastic Gradient Descent Algorithm

In most maternity hospitals, an ultrasound scan in the mid-trimester is now a standard element of antenatal care. More fetal abnormalities are being detected in scans as technology advances and ability improves. Fetal anomalies are developmental abnormalities in a fetus that arise during pregnancy, birth defects and congenital abnormalities are related terms. Fetal abnormalities have been commonly observed in industrialized countries over the previous few decades. Three out of every 1000 pregnant mothers suffer a fetal anomaly. This research work proposes an Adaptive Stochastic Gradient Descent Algorithm to evaluate the risk of fetal abnormality. Findings of this work suggest that proposed innovative method can successfully classify the anomalies linked with nuchal translucency thickening. Parameters such an accuracy, recall, precision, and F1-score are analyzed. The accuracy achieved through the suggested technique is 98.642.%.

Impact of variation in practice in the prenatal reporting of variants of uncertain significance by commercial laboratories: NEED FOR GREATER ADHERENCE TO PUBLISHED GUIDELINES

OBJECTIVE

To evaluate the impact of implementing commercial whole exome sequencing (WES) and targeted gene panel testing in pregnancies with fetal anomalies.

METHODS

A retrospective chart review of 124 patients with sequencing performed by commercial laboratories.

RESULTS

The diagnostic yield of WES and panel testing was 21.5% and 26% respectively, based on likely pathogenic (LP) or pathogenic (P) variants. Forty-two per cent of exomes and 32% of panels analyzed had one or more variant of uncertain significance (VUS) reported. A multidisciplinary in depth review of the fetal phenotype, disease phenotype, variant data, and, in some patients, additional prenatal or postnatal investigations increased the diagnostic yield by 5% for exome analysis and 6% for panel analysis.

CONCLUSIONS

The diagnostic yield of WES and panel testing combined was 23% based on LP and P variants. Although the reporting of VUS contributed to a 5% increase in diagnostic yield for WES and 6% for panels, the large number of VUS reported by commercial laboratories has significant resource implications. Our results support the need for greater adherence to the recommendations on the prenatal reporting of VUS and the importance of a multidisciplinary approach that brings together clinical and laboratory expertise in prenatal genetics and genomics. This article is protected by copyright. All rights reserved.

Universal third-trimester obstetrical ultrasonography: a cross-sectional analysis of a national survey

BACKGROUND

Universal third-trimester obstetrical ultrasonography represents a medical debate. The current survey was conducted to evaluate the actual use of third-trimester scan and understand gynecologists' aptitude.

METHODS

A survey was mailed to 128 gynecologists between January and February 2020. Data about their demographic's characteristics, hospital ward, and self-assessment questionnaires were recorded. Results were evaluated by using combined analysis.

RESULTS

Overall, 128 (29.8%) gynecologists answered. Their age ranged between 45 and 64 years (70.3% of the total, 90/128). The half part worked in hospitals and university hospitals (39.8%, 51/128 and 10.1%, 13/128, respectively), 26.5% (34/128) worked in private hospitals and 23.4% (30/128) in public ambulatories. The neonatal intensive care unit was present in 37.5% (48/128) of the cases. 96.0% of gynecologists surveyed (123/128) offered the universal third-trimester scan (28-32 weeks) and 78.1% of the physician recommended the universal 35-37 weeks ultrasonographical exam. A subanalysis among third level hospital gynecologists versus gynecologists without neonatal intensive care unit showed no statistical difference.

CONCLUSIONS

This survey reveals extensive use of third-trimester scan in low-risk pregnancy. Nevertheless, randomized controlled trials concerning the universal third-trimester scan are required to validate this clinical attitude.

Prenatal Hydronephrosis: Bridging Pre- and Postnatal Management

Urinary tract dilation (UTD), including hydronephrosis (HN) is the most common prenatally detected anomaly and affects up to 1-2% of pregnancies. Postnatally, it resolves without surgical intervention in approximately 75-80% of children, however this may take several years to occur, necessitating repeated clinic visits and additional invasive testing for many. For the remainder, a surgical intervention will be offered to relieve obstruction or to correct vesicoureteral reflux. During the monitoring period, many of these infants will be offered continuous antibiotic prophylaxis for the prevention of urinary tract infections, however this remains a controversial topic among pediatric urologists and nephrologists. Herein, we present an up-to-date review of the early management of prenatally detected UTD including timing of postnatal imaging, the use of antibiotics, when circumcision may be beneficial and long term outcomes of the most common HN etiologies. We also propose a decision making tool to help guide the care of infants with UTD. This article is protected by copyright. All rights reserved.

The Effect of COVID-19 Infection During Pregnancy; Evaluating Neonatal Outcomes and the Impact of the B.1.1.7. Variant

BACKGROUND

Coronavirus disease 2019 (COVID-19) infection during pregnancy has been associated with adverse perinatal outcomes. We aim to evaluate the neonatal outcomes including the incidence of preterm birth, admission to the neonatal unit and incidence of congenital anomalies in this cohort. We will also describe these outcomes in the context of the B.1.1.7. variant outbreak, the dominant variant in Ireland since January 2021, which has had a greater impact on pregnant patients.

METHODS

This was a retrospective study of liveborn infants, delivered between 1st March 2020 and 1st March 2021, to women with a severe acute respiratory syndrome coronavirus 2 diagnosis during pregnancy, in a tertiary maternity hospital (8,500 deliveries/year). Clinical data were collected, and analyses were performed to evaluate the impact of maternal symptom status, time from diagnosis to delivery and the B.1.1.7. variant on neonatal outcome.

RESULTS

In total 133 infants (1.6%) were born to women with severe acute respiratory syndrome coronavirus 2 identified during pregnancy. The median birth weight was 3.45 kg and gestational age at birth was 39.3 weeks. 14 infants (10.5%) were preterm. 22 infants (16.5%) required admission to the neonatal unit and 7 (5.3%) were small for gestational age. There was no difference in growth, preterm birth or neonatal unit admission based on maternal symptom status or infection after the outbreak of B.1.1.7. as the dominant strain.

CONCLUSIONS

Following a COVID-19 infection in pregnancy, there was no increase in the incidence of preterm birth or neonatal intensive care unit admission compared with 5-year hospital data. Maternal symptom status did not influence neonatal outcomes. Further studies to evaluate the impact of COVID-19 in early pregnancy, the variants of concern, particularly the emerging Delta variant and COVID-19 placentitis are required.

Transforming obstetric ultrasound into data science using eye tracking, voice recording, transducer motion and ultrasound video

Ultrasound is the primary modality for obstetric imaging and is highly sonographer dependent. Long training period, insufficient recruitment and poor retention of sonographers are among the global challenges in the expansion of ultrasound use. For the past several decades, technical advancements in clinical obstetric ultrasound scanning have largely concerned improving image quality and processing speed. By contrast, sonographers have been acquiring ultrasound images in a similar fashion for several decades. The PULSE (Perception Ultrasound by Learning Sonographer Experience) project is an interdisciplinary multi-modal imaging study aiming to offer clinical sonography insights and transform the process of obstetric ultrasound acquisition and image analysis by applying deep learning to large-scale multi-modal clinical data. A key novelty of the study is that we record full-length ultrasound video with concurrent tracking of the sonographer's eyes, voice and the transducer while performing routine obstetric scans on pregnant women. We provide a detailed description of the novel acquisition system and illustrate how our data can be used to describe clinical ultrasound. Being able to measure different sonographer actions or model tasks will lead to a better understanding of several topics including how to effectively train new sonographers, monitor the learning progress, and enhance the scanning workflow of experts.

Simulating realistic fetal neurosonography images with appearance and growth change using cycle-consistent adversarial networks and an evaluation

Purpose: We present an original method for simulating realistic fetal neurosonography images specifically generating third-trimester pregnancy ultrasound images from second-trimester images. Our method was developed using unpaired data, as pairwise data were not available. We also report original insights on the general appearance differences between second- and third-trimester fetal head transventricular (TV) plane images. Approach: We design a cycle-consistent adversarial network (Cycle-GAN) to simulate visually realistic third-trimester images from unpaired second- and third-trimester ultrasound images. Simulation realism is evaluated qualitatively by experienced sonographers who blindly graded real and simulated images. A quantitative evaluation is also performed whereby a validated deep-learning-based image recognition algorithm (ScanNav®) acts as the expert reference to allow hundreds of real and simulated images to be automatically analyzed and compared efficiently. Results: Qualitative evaluation shows that the human expert cannot tell the difference between real and simulated third-trimester scan images. 84.2% of the simulated third-trimester images could not be distinguished from the real third-trimester images. As a quantitative baseline, on 3000 images, the visibility drop of the choroid, CSP, and mid-line falx between real second- and real third-trimester scans was computed by ScanNav® and found to be 72.5%, 61.5%, and 67%, respectively. The visibility drop of the same structures between real second-trimester and simulated third-trimester was found to be 77.5%, 57.7%, and 56.2%, respectively. Therefore, the real and simulated third-trimester images were consider to be visually similar to each other. Our evaluation also shows that the third-trimester simulation of a conventional GAN is much easier to distinguish, and the visibility drop of the structures is smaller than our proposed method. Conclusions: The results confirm that it is possible to simulate realistic third-trimester images from second-trimester images using a modified Cycle-GAN, which may be useful for deep learning researchers with a restricted availability of third-trimester scans but with access to ample second trimester images. We also show convincing simulation improvements, both qualitatively and quantitatively, using the Cycle-GAN method compared with a conventional GAN. Finally, the use of a machine learning-based reference (in the case ScanNav®) for large-scale quantitative image analysis evaluation is also a first to our knowledge.