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

Quantitative Approach to Quality Review of Prenatal Ultrasound Examinations: Incomplete Detailed Fetal Anatomy Exams

Background/Objectives: It is challenging to obtain all the required views for a fetal anatomy ultrasound examination, so exams are often incomplete. Our objective was to develop and demonstrate quantitative methods to assess the overall rate of incomplete exams for an ultrasound practice and for individual examiners. Methods: We performed a retrospective quality review of all detailed fetal anatomy exams at seven maternal-fetal medicine practices in 2024 with singleton pregnancies and cardiac activity present. The exams were considered incomplete if any of the 36 required anatomy views were reported as inadequate. The analysis focused on exams at a gestational age (GA) of 18.0 to 23.9 weeks. The rates of incomplete exams were tabulated across practices and for individual sonographers and physicians. Multivariable logistic regression was used to adjust for known covariates. Results: In total, 15,723 detailed fetal anatomy exams were performed at 18.0-23.9 weeks of gestation. Incomplete exams were significantly more common with maternal obesity, prior cesarean, maternal age < 35 years and GA < 19 weeks. There were significant between-practice differences in the rate of incomplete exams, varying from 1% to 53%. Incomplete exams had a median of four inadequate views (interquartile range 2-7). Practices also varied significantly in the rate of missing measurements for nuchal fold (0 to 9%) and nose bone length (11-100%). There were significant between-individual differences in the rate of incomplete exams. The tabulation of specific views showed some individuals with very high rates of inadequate views of certain elements. Conclusions: For some practices, there is a need for practice-wide quality improvement to increase the rate of measurement of the nuchal fold and nose bone. For selected individuals, the tabulation of which anatomy elements were inadequate can identify areas for targeted education or mentorship. We suggest strategies and software enhancements that may reduce the rate of incomplete exams. Sample data and statistical analysis scripts are provided for those who wish to adopt these methods to review their own data.

Update on Management and Outcomes of Monochorionic Twin Pregnancies

The management of multiple pregnancies complicated by monochorionicity continues to evolve as new investigations support a change in clinical practice to optimize outcomes. Monochorionic twins are at risk of unique conditions such as monoamnionicity, conjoined twinning, twin reversed arterial perfusion sequence, twin-twin transfusion syndrome, twin anemia-polycythemia sequence, unequal placental sharing with discordant twin growth or selective fetal growth restriction, and single-twin death that puts co-twins at risk of death or neurologic injury attributable to the shared placenta. Contemporary practice guidelines recommend serial ultrasonographic surveillance of monochorionic pregnancies to increase the early detection of problems and timely management decisions that may include increased surveillance, selective reduction or pregnancy termination, referral for in utero treatment, or earlier delivery than initially planned. Improvements in prenatal diagnosis and antenatal testing and advances in fetal therapy have contributed to more favorable outcomes in these complicated monochorionic gestations.

Spectrum of congenital anomalies detected through anatomy ultrasound at a referral hospital in Ghana

BACKGROUND

Africa has a high burden of congenital anomalies due in part to limited preconception care, infections, and environmental exposures. However, the true prevalence of congenital anomalies is unclear because of insufficient access to prenatal diagnostic services. We aimed to determine the rate of congenital anomalies, and characterize the anomalies detected prenatally at a referral hospital in Ghana.

METHODS

We performed a four-year retrospective review of all fetal anomaly ultrasounds performed and congenital anomalies detected from January 1st, 2020, to December 31st, 2023, at Korle Bu Teaching Hospital, Accra, Ghana. Data were extracted from the electronic database on maternal age, gestational age at time of ultrasound, and occupation. Detected congenital anomalies were identified, and each anomaly was categorized by ICD-10 code and EUROCAT classification. Descriptive statistics were performed.

RESULTS

The mean maternal age and median gestational age at the time of ultrasound were 31.1 (SD 6.3) years and 26.9 (IQR 22.5-31.0) weeks, respectively. 3,981 anatomy ultrasounds were performed during the study period, and 7.0% (280/3,981) of fetuses had anomalies. Most (70.7%, 198/280) had anomalies detected in an isolated organ system. Anomalies were most identified in the central nervous system (CNS) (45.0%, 126/280), genitourinary (GU) (28.6%, 80/280), and gastrointestinal (GI) systems (21.8%, 61/280). The most common CNS anomaly identified was ventriculomegaly (70.6%, 89/126), out of which 26.2% (33/126) had severe ventriculomegaly, with an overall detection rate of 0.8% (33/3,981). The most common GU anomalies were congenital hydronephrosis (70.0%, 56/80), and congenital posterior urethral valves (28.8%, 23/80). The most common GI anomalies were exomphalos (49.2%, 30/61), and duodenal atresia (23.0%, 14/61). Unrelated to a specific organ system, 3.2% (9/280) of cases had hydrops and 6.1% (17/280) had an associated soft marker of aneuploidy.

CONCLUSIONS

Our study highlights the substantial burden of congenital anomalies detected through prenatal ultrasound at a tertiary referral center in Ghana, with a notably high detection rate of severe ventriculomegaly. This work underscores the feasibility and importance of performing detailed anatomy ultrasounds in Africa. Beyond the clinical benefit, these data lay the groundwork for studies to identify the underlying causes of high rates of anomalies to inform preventive policy and clinical interventions in low-resource settings.

Automated craniofacial biometry with 3D T2w fetal MRI

OBJECTIVES

Evaluating craniofacial phenotype-genotype correlations prenatally is increasingly important; however, it is subjective and challenging with 3D ultrasound. We developed an automated label propagation pipeline using 3D motion- corrected, slice-to-volume reconstructed (SVR) fetal MRI for craniofacial measurements.

METHODS

A literature review and expert consensus identified 31 craniofacial biometrics for fetal MRI. An MRI atlas with defined anatomical landmarks served as a template for subject registration, auto-labelling, and biometric calculation. We assessed 108 healthy controls and 24 fetuses with Down syndrome (T21) in the third trimester (29-36 weeks gestational age, GA) to identify meaningful biometrics in T21. Reliability and reproducibility were evaluated in 10 random datasets by four observers.

RESULTS

Automated labels were produced for all 132 subjects with a 0.3% placement error rate. Seven measurements, including anterior base of skull length and maxillary length, showed significant differences with large effect sizes between T21 and control groups (ANOVA, p<0.001). Manual measurements took 25-35 minutes per case, while automated extraction took approximately 5 minutes. Bland-Altman plots showed agreement within manual observer ranges except for mandibular width, which had higher variability. Extended GA growth charts (19-39 weeks), based on 280 control fetuses, were produced for future research.

CONCLUSION

This is the first automated atlas-based protocol using 3D SVR MRI for fetal craniofacial biometrics, accurately revealing morphological craniofacial differences in a T21 cohort. Future work should focus on improving measurement reliability, larger clinical cohorts, and technical advancements, to enhance prenatal care and phenotypic characterisation.

Chromosomal Microarray Analysis in Fetuses with Ultrasound Abnormalities

Objective

To explore and evaluate the value of chromosomal microarray analysis (CMA) in prenatal diagnosis of fetuses with ultrasound abnormalities.

Methods

A retrospective analysis was performed on 370 fetuses with ultrasound abnormalities received invasive prenatal diagnosis at Meizhou People's Hospital from October 2022 to December 2023. Fetal specimens were analyzed by CMA, and the detection rates of aneuploidy and pathogenic (P)/likely pathogenic (LP) copy number variations (CNVs) in ultrasound structural abnormalities (malformations of fetal anatomy) and non-structural abnormalities (abnormalities of fetal nonanatomical structure) were analyzed.

Results

There were 114 (30.8%) cases with isolated ultrasound structural abnormalities, 226 (61.1%) cases with isolated non-structural abnormalities (182 isolated ultrasound soft markers abnormalities, 30 isolated fetal growth restriction (FGR), and 8 isolated abnormalities of amniotic fluid volume), and 30 (8.1%) cases with both structural and non-structural abnormalities. The overall detection rate of aneuploidy and P/LP CNVs in isolated ultrasonic structural abnormalities was 5.3%, among which cardiovascular system abnormalities were the highest. In addition, the largest number of fetuses with non-structural abnormalities was nuchal translucency (NT) thickening (n = 81), followed by ventriculomegaly (n = 29), and nasal bone dysplasia (n = 24). The detection rate of chromosomal abnormalities of fetuses with abnormal ultrasound soft markers was 9.9%, and the detection rate in single abnormal ultrasound soft marker, and multiple ultrasound soft markers abnormalities was 9.7% (16/165) and 11.8% (2/17), respectively. Moreover, the detection rate of chromosomal abnormalities of fetuses with FGR and structural abnormalities combined with non-structural abnormalities was 6.7% (2/30), and 13.3% (4/30), respectively.

Conclusion

The incidence of chromosomal abnormalities (aneuploidy and P/LP CNVs) varies among different fetal ultrasound abnormalities.

Automated Craniofacial Biometry with 3D T2w Fetal MRI

Objectives

Evaluating craniofacial phenotype-genotype correlations prenatally is increasingly important; however, it is subjective and challenging with 3D ultrasound. We developed an automated landmark propagation pipeline using 3D motion-corrected, slice-to-volume reconstructed (SVR) fetal MRI for craniofacial measurements.

Methods

A literature review and expert consensus identified 31 craniofacial biometrics for fetal MRI. An MRI atlas with defined anatomical landmarks served as a template for subject registration, auto-labelling, and biometric calculation. We assessed 108 healthy controls and 24 fetuses with Down syndrome (T21) in the third trimester (29-36 weeks gestational age, GA) to identify meaningful biometrics in T21. Reliability and reproducibility were evaluated in 10 random datasets by four observers.

Results

Automated labels were produced for all 132 subjects with a 0.03% placement error rate. Seven measurements, including anterior base of skull length and maxillary length, showed significant differences with large effect sizes between T21 and control groups (ANOVA, p<0.001). Manual measurements took 25-35 minutes per case, while automated extraction took approximately 5 minutes. Bland-Altman plots showed agreement within manual observer ranges except for mandibular width, which had higher variability. Extended GA growth charts (19-39 weeks), based on 280 control fetuses, were produced for future research.

Conclusion

This is the first automated atlas-based protocol using 3D SVR MRI for fetal craniofacial biometrics, accurately revealing morphological craniofacial differences in a T21 cohort. Future work should focus on improving measurement reliability, larger clinical cohorts, and technical advancements, to enhance prenatal care and phenotypic characterisation.