Prenatal sonographic detection of birth defects in 18 hospitals from South America

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.

Thoracic kidney and diaphragmatic hernia: prenatal diagnosis and successful management. Case report and review of the literature

Objectives

To report a case of prenatal diagnosis of ectopic intrathoracic kidney with diaphragmatic hernia managed surgically after birth, and to conduct a review of the literature on prenatal diagnosis of ectopic intrathoracic kidney and perinatal prognosis.

Material and methods

We report the case of a 28-week fetus in which, on ultrasound imaging, a mass was observed displacing the heart and lung in the right hemithorax, which was was confirmed by magnetic resonance (MR) to be an ectopic intrathoracic kidney (ITEK). After birth, the neonate was approached by laparoscopy to place a mesh in continuity with the diaphragm, leaving the kidney in the abdomen, with good evolution. A search was conducted in the PubMed, Embase and Cochrane databases for cohorts, case reports and case series of prenatal diagnosis of intrathoracic kidney in the fetus. Information was retrieved regarding design, population, imaging diagnosis, treatment and prognosis.

Results

The search identified 8 studies that met the inclusion criteria, reporting a total of 8 cases. Ultrasound diagnosis showed ectopic intrathoracic kidney associated with diaphragmatic hernia in all the subjects. Fetal magnetic resonance imaging (MRI) was also used in 5 cases.

Conclusions

Ectopic intrathoracic kidney is a congenital abnormality amenable to prenatal diagnosis. Survival after corrective surgery performed in the neonatal period is common. There is a paucity of publications, limited to case reports, regarding the prenatal diagnosis of this condition.

Characterization of Risk Factors for Neural Tube Defects: A Case-Control Study in Bogota and Cali, Colombia, 2001-2018

Worldwide prevalence of neural tube defects is between 1.2 and 124.1 per 10 000 live births. This study analyzes risk factors linked with neural tube defects. The study focused on the Surveillance and Monitoring Programs of Congenital Anomalies databases in Bogota and Cali. Births were monitored between 2001 and 2018. Liveborn or stillborn with neural tube defects were defined as cases, using a case-control ratio of 1:4. Paternal age, folic acid supplementation, birth weight, urban or rural origin, maternal and paternal studies, and socioeconomic levels were analyzed. Across the 215 730 births monitored, 147 cases with a rate of 6.82/10 000 live births were found (6.79-6.85). In isolated cases, lower birth weight had a P <.01. Paternal age >45 years showed an odds ratio (OR) of 4.24 (1.54-11.65), socioeconomic status 1 and 2, OR of 2.49 (1.63-3.82), maternal primary schooling or lower OR 2.61 (1.28-5.31), and housing in urban areas OR 2.4 (1.4-4.09).

Investigating the use of ultrasonography for the antenatal diagnosis of structural congenital anomalies in low-income and middle-income countries: a systematic review

BACKGROUND

Congenital anomalies are the fifth leading cause of under-5 mortality globally. The greatest burden is faced by those in low/middle-income countries (LMICs), where over 95% of deaths occur. Many of these deaths may be preventable through antenatal diagnosis and early intervention. This systematic literature review investigates the use of antenatal ultrasound to diagnose congenital anomalies and improve the health outcomes of infants in LMICs.

METHODS

A systematic literature review was conducted using three search strings: (1) structural congenital anomalies; (2) LMICs; and (3) antenatal diagnosis. The search was conducted on the following databases: Medline, Embase, PubMed and the Cochrane Library. Title, abstract and full-text screening was undertaken in duplicate by two reviewers independently. Consensus among the wider authorship was sought for discrepancies. The primary analysis focused on the availability and effectiveness of antenatal ultrasound for diagnosing structural congenital anomalies. Secondary outcomes included neonatal morbidity and mortality, termination rates, referral rates for further antenatal care and training level of the ultrasonographer. Relevant policy data were sought.

RESULTS

The search produced 4062 articles; 97 were included in the review. The median percentage of women receiving an antenatal ultrasound examination was 50.0% in African studies and 90.7% in Asian studies (range 6.8%-98.8%). Median detection rates were: 16.7% Africa, 34.3% South America, 34.7% Asia and 47.3% Europe (range 0%-100%). The training level of the ultrasound provider may affect detection rates. Four articles compared morbidity and mortality outcomes, with inconclusive results. Significant variations in termination rates were found (0%-98.3%). No articles addressed referral rates.

CONCLUSION

Antenatal detection of congenital anomalies remains highly variable across LMICs and is particularly low in sub-Saharan Africa. Further research is required to investigate the role of antenatal diagnosis for improving survival from congenital anomalies in LMICs.

PROSPERO REGISTRATION NUMBER

CRD42019105620.

Prenatal detection of congenital anomalies and related factors in Argentina

Congenital anomalies (CAs) are a leading cause of neonatal death. Many CAs can be diagnosed prenatally. To estimate the prenatal detection rate (PDR) of CA in hospitals participating in the RENAC (National Network of Congenital Anomalies of Argentina) and to analyze the PDR according to different factors. Sources were reports of RENAC from the 2013-2016 period. Congenital anomalies included were those detectable by ultrasound or by a prenatal karyotype. PDR was calculated by region, health subsector, clinical presentation, maternal age, sex, and twining. Using multiple logistic regression analysis, we evaluated predictors of prenatal detection. In total, 9976 cases were defined as prenatal detectable; 5021 were detected (PDR = 50.3%). Multiple presentation increased the chances of prenatal detection (Adj. OR = 1.6; 95%CI 1.4-1.9). Prenatal detection was lower in the public subsector (Adj. OR = 0.8; 95%CI 0.7-0.9) and in the northern regions of the country. PDR was higher than 75% in isolated cases of urinary malformation, anencephaly, and gastroschisis. Prenatal detection increased the chance of birth in higher complexity-level hospitals (Adj. OR = 2.5; 95%CI 2.3-2.8). PDR was within the range previously reported. Heterogeneity between regions and health subsector suggests the need for training to achieve equity in detection.

Barriers to Sonographer Screening for Fetal Heart Defects: A U.S. National Survey

OBJECTIVE

We surveyed obstetric sonographers, who are at the forefront of the screening process to determine how barriers to prenatal cardiac screening impacted screening abilities.

METHODS

We performed a cross-sectional national survey of obstetric sonographers in the United States using a sampling frame from American Registry of Diagnostic Medical Sonography mailing lists. The web survey measured the ability to obtain and interpret fetal heart images. Several cognitive, sociodemographic, and system-level factors were measured, including intention to perform cardiac imaging. Regression and mediation analyses determined factors associated with intention to perform and ability to obtain and interpret cardiac images. Subgroup analyses of sonographers in tertiary versus nontertiary centers were also performed.

RESULTS

Survey response rate either due to noncontact or nonresponse was 40%. Of 480 eligible sonographers, ~30% practiced in tertiary settings. Sonographers had lower intention to perform outflow views compared to 4 chambers. Higher self-efficacy and professional expectations predicted higher odds of intention to perform outflow views (OR 2.8, 95% CI 1.9-4.2 and 1.9, 95% CI 1.1-3.0, respectively). Overall accuracy of image interpretation was 65% (±14%). For the overall cohort and nontertiary subgroup, higher intention to perform outflows was associated with increased accuracy in overall image interpretation. For the tertiary subgroup, self-efficacy and feedback were strongly associated with accuracy.

CONCLUSIONS

We identified several modifiable (some heretofore unrecognized) targets to improve prenatal cardiac screening. Priorities identified by sonographers that are associated with screening success should guide future interventions.

Birth prevalence of Down syndrome in Argentina

The aim of this study was to describe the prevalence at birth of Down syndrome in Argentina. The prevalence by jurisdiction and maternal age was calculated for the 2009-2015 period and the prevalence and proportion of prenatal diagnosis was compared according to sub-sector (public and private) and complexity level of the maternity wards. The association of Down syndrome with birth weight and gestational age was analyzed. The data source was the National Network of Congenital Anomalies of Argentina [Red Nacional de Anomalías Congénitas] (RENAC). The prevalence was 17.26 per 10,000 births; by jurisdictions it varied between 10.99 and 23.71; and by maternal age, between 10.32 in women <20 years of age and 158.06 in those ≥45 years of age. In hospitals of the private subsector there was a higher prevalence, attributable to differences in the structure of maternal age, and a greater proportion of prenatal diagnosis. There was a negative correlation between birth weight and Down syndrome (ß=-294.7; p<0.001). No difference in the median gestational age at birth between Down syndrome newborns and newborns without major anomalies was found, but the distribution of gestational age differed. Knowledge of certain epidemiological characteristics of this health issue could contribute to the implementation of health policies.

A consensus statement on birth defects surveillance, prevention, and care in Latin America and the Caribbean

Birth defects contribute up to 21% of the mortality in those under 5 years of age in Latin America and the Caribbean (LAC), and that burden has been compounded by the Zika virus epidemic. In 2001, the March of Dimes launched a series of biennial assemblies called the International Conference on Birth Defects and Disabilities in the Developing World (ICBD). The latest ICBD, in 2017, convened in Bogotá, Colombia, and was attended by over 300 professionals, policymakers, and donors. The conference attendees, a majority of whom were from LAC, supported a call to action in the form of a consensus statement. The consensus statement lists key actions for maximizing birth defects surveillance, prevention, and care in LAC: 1) improving surveillance; 2) reducing risks for birth defects; 3) fortifying staple foods; 4) preventing and treating infections associated with birth defects; 5) implementing newborn screening; 6) providing care and services for people with birth defects and disabilities; 7) involving governments, civil society, and international agencies; and 8) advancing research for birth defects. Implementation and scale-up of evidence-based interventions using multisectoral and multidisciplinary collaborative approaches were endorsed. LAC countries can leverage technology and social media to advance and advocate for approaches identified in the consensus statement. The consensus statement can be used as a guide by both governments and nongovernmental agencies to take immediate steps for improving the quality of life of those living with birth defects and associated disabilities in the LAC countries.

First trimester sonographic diagnosis of orofacial defects. Review of literature

Ultrasound has been used since the 1950s as a useful tool for the screening of several pregnancy abnormalities. The National Institute for Excellence in Health and Care (NICE) guidelines for prenatal control recommend its routine use between 12 and 20 weeks of gestational age, given that during the first trimester, a series of very frequent markers that determine a high risk of fetal anomalies can be evaluated. Among these markers, the most frequently studied are: increased nuchal translucency, the absence of nasal bones, increased tricuspid regurgitation, and altered flow in the venous duct. There is also a new ultrasound technique consisting of the evaluation of the retronasal triangle view, which captures the coronal plane of the face in which the primary palate and the frontal process of the maxillary are simultaneously visualized, presenting high sensitivity and specificity for malformations such as oropalatine clefts, malformations of the nasal bones, and micrognathia. The purpose of this article is to make a comprehensive review of first trimester sonographic diagnosis of orofacial defects.

Mapping the landscape of global programmes to evaluate health interventions in pregnancy: the need for harmonised approaches, standards and tools

Pregnant women and their babies are among the populations most vulnerable to untoward health outcomes. Yet current standards for evaluating health interventions cannot be met during pregnancy because of lack of adequate evidence. The situation is even more concerning in low-income and middle-income countries, where the need for effective interventions is the greatest. Meeting the Sustainable Development Goals for health will require strengthened attention to maternal and child health. In this paper we examine ongoing initiatives aimed at improving the assessment of maternal interventions. We review current methodologies to monitor outcomes of maternal interventions and identify where harmonisation is needed. Based on this analysis we identify settings where different minimal data sets should be considered taking into consideration the clinical realities. Stronger coordination mechanisms and a roadmap to support harmonised monitoring of maternal interventions across programmes and partners, working on improving pregnancy and early childhood health events, will greatly enhance ability to generate evidence-based policies.

Noninvasive prenatal screening for fetal common sex chromosome aneuploidies from maternal blood

Objective

To explore the feasibility of high-throughput massively parallel genomic DNA sequencing technology for the noninvasive prenatal detection of fetal sex chromosome aneuploidies (SCAs).

Methods

The study enrolled pregnant women who were prepared to undergo noninvasive prenatal testing (NIPT) in the second trimester. Cell-free fetal DNA (cffDNA) was extracted from the mother’s peripheral venous blood and a high-throughput sequencing procedure was undertaken. Patients identified as having pregnancies associated with SCAs were offered prenatal fetal chromosomal karyotyping.

Results

The study enrolled 10 275 pregnant women who were prepared to undergo NIPT. Of these, 57 pregnant women (0.55%) showed fetal SCA, including 27 with Turner syndrome (45,X), eight with Triple X syndrome (47,XXX), 12 with Klinefelter syndrome (47,XXY) and three with 47,XYY. Thirty-three pregnant women agreed to undergo fetal karyotyping and 18 had results consistent with NIPT, while 15 patients received a normal karyotype result. The overall positive predictive value of NIPT for detecting SCAs was 54.54% (18/33) and for detecting Turner syndrome (45,X) was 29.41% (5/17).

Conclusion

NIPT can be used to identify fetal SCAs by analysing cffDNA using massively parallel genomic sequencing, although the accuracy needs to be improved particularly for Turner syndrome (45,X).

Maternal reporting of prenatal ultrasounds among women in the National Birth Defects Prevention Study

BACKGROUND

Increased availability and usage of ultrasound screening have led to improved identification of fetal structural abnormalities prenatally. Few population-based studies have been published on prenatal detection for structural birth defects in the United States. The aim of this study is to determine the frequency of maternal reporting of abnormal prenatal ultrasounds for selected birth defects and to investigate associated maternal characteristics.

METHODS

Participants included 4013 mothers enrolled in the National Birth Defects Prevention Study who carried a fetus with at least one of 14 structural birth defects between 1997 and 2004. Frequencies of abnormal prenatal ultrasounds were based on maternal report and computed for isolated and multiple defects. Associations between maternal characteristics and abnormal prenatal ultrasounds were assessed using logistic regression.

RESULTS

Overall, 46% of participants reported an abnormal ultrasound. Infants with omphalocele, anencephaly, gastroschisis, and renal agenesis were more likely to have abnormal prenatal ultrasounds than those with cleft and limb abnormalities. Hispanic women were less likely to report abnormal prenatal ultrasounds of birth defects than Caucasians, as were women who had a body mass index ≥ 30 kg/m(2) compared with those with a normal body mass index.

CONCLUSION

Of the 14 selected birth defects in this study, less than half were reported by mothers of affected infants to have had an abnormal ultrasound during pregnancy. The frequency of reporting abnormal prenatal ultrasounds varies by type of defect, maternal race/ethnicity, and maternal body mass index status.

The use of a Toolkit for health needs assessment on neural tube defects in Argentina

Health needs assessment (HNA) is a commonly used process for those working in public health. The PHG Foundation has developed a Toolkit to provide users with a stepwise approach for undertaking a HNA on birth defects. We report the findings from using the Toolkit to examine needs in relation to policies and programs, services, and interventions for neural tube defects (NTDs) in Argentina. The trend over the last few decades is one of decline in infant mortality from nutritional and infectious causes, thus further increasing the relative importance of birth defects. The observed prevalence of NTDs is consistent with that reported internationally. Since 2002 folic acid fortification (FAF) has been mandatory by law, and different studies have shown at least a 50 % decrease in the birth prevalence of NTDs after FAF. In Argentina, there is inequity between the public and non-public health sectors. The birth prevalence of NTDs seems lower in the non-public sector, possibly as a result of better nutritional status of women, higher access to folic acid supplementation, and earlier prenatal diagnosis followed by termination of pregnancy (ToP) in non-public hospitals. Although illegal, ToP is believed to be widespread, with better access for people of higher socioeconomic status. Through the process of HNA, we identified several unmet needs regarding registration of cases, public and professional education, legislation, and organization of care pathways. In our experience, the Toolkit brought together people working on the same issue, and it engaged and motivated experts and stakeholders to work together to tackle the problem.