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This article explores the development and prenatal imaging of the corpus callosum (CC), a crucial structure in the brain that facilitates communication between the two hemispheres. Prenatal imaging techniques like ultrasound and MRI have made it possible to study the CC's development earlier than before. The article also discusses the various abnormalities that can be observed in the CC during prenatal imaging and the challenges in accurately describing and classifying these abnormalities. The authors propose a simplified classification system based on well-defined criteria to improve the diagnosis and prognosis of CC anomalies. [Extracted from the article]

Objectives: Our objectives were: (1) to assess the visualization rate of the choroid bar in a consecutive series of 306 first‐trimester scans; (2) to verify, in this cohort of fetuses, the normality of the posterior fossa later in pregnancy; and (3) to confirm the non‐visualization of the choroid bar in a retrospective series of fetuses with posterior fossa malformations. Methods: This study included a prospective and a retrospective series. The former comprised 306 fetuses undergoing routine obstetric ultrasound at our unit in both the first and second trimesters over a 6‐month period, while the latter comprised 12 cases of posterior fossa malformations. In the prospective study, the presence of the choroid bar, which is defined as a visually continuous, homogeneously hyperechogenic, thick structure bridging the cisterna magna from side to side, was evaluated at the end of the first‐trimester nuchal translucency scan. In the retrospective study, previously acquired three‐dimensional volume datasets were processed in order to assess whether the choroid bar could be visualized in cases of open spinal dysraphisms and vermian cystic anomalies. In the prospective study, confirmation of a normal posterior fossa was based on the sonographic features of this anatomical region at the time of the second‐trimester anomaly scan at 19–21 weeks' gestation, while, in the retrospective study, it was based on autopsy results, when available, or further direct imaging of the defect later in pregnancy. Results: In the prospective study, the choroid bar could be visualized in all 306 fetuses, on transabdominal ultrasound in 287 (93.8%) cases and on transvaginal ultrasound in 19 (6.2%) cases. The choroid bar was displayed with a ventral/dorsal approach in 67 (21.9%) cases, with a lateral approach in 56 (18.3%) cases and with both in 183 (59.8%) cases. All 306 cases were confirmed to have a sonographically normal posterior fossa at 19–21 weeks. On the other hand, in the retrospective study, it was not possible to visualize the choroid bar in any of the fetuses with posterior fossa malformations. Conclusions: We have described a new sign, the choroid bar, consistent with a normal posterior fossa at 12–14 weeks' gestation. The choroid bar provides the option of screening for major abnormalities of the posterior fossa, since its absence raises suspicion of both open spinal dysraphisms and posterior fossa cystic malformations. At the same time, it is easy to visualize, as it can be seen with all lines of insonation. © 2023 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

This article discusses a study that aims to demonstrate the scientific validity of a novel cell-based non-invasive prenatal testing (cbNIPT) method for detecting fetal copy number variants (CNVs) using single cell sequencing of circulating extravillous trophoblasts (cEVTs). The study enrolled 1388 high-risk pregnancies and found a screen positive rate of 18.9% for aneuploidies and 11.2% for pCNVs. The results showed that cbNIPT was able to detect pCNVs <1 Mb in size, which is below the resolution of cell-free DNA screening. The authors conclude that analyzing cEVTs from maternal blood could significantly reduce the residual risk for pCNVs in early gestational weeks. [Extracted from the article]

Objectives: To compile a list of instant diagnoses of major fetal anomalies, and to present their sonographic descriptors and test them in a retrospective series of fetuses with congenital anomalies managed at our center. Methods: The first step was to identify major anomalies that meet the following criteria: (1) can be diagnosed directly and unequivocally on the basis of a set of descriptors evident on a single sonographic view; (2) are among those more commonly diagnosed in utero; (3) represent major lethal or life‐threatening malformations or anomalies for which no or only palliative surgery can be performed. For each of these anomalies, a sonographic descriptor was produced. The second step was to test the descriptors of the instant diagnoses in all cases with these anomalies evaluated since January 2000 in our Fetal Medicine Unit, retrieved from our electronic database. For each congenital anomaly–sonographic descriptor pair we then evaluated the presence vs absence of an unequivocal relationship between anomaly and descriptor, assessing: whether a particular descriptor in a set reference plane identified unequivocally the anomaly, i.e. the same descriptor could not be found in any other malformation; and whether a particular anomaly presented the corresponding descriptor in all cases. Finally, we evaluated whether the sonographic descriptors could be applied in all trimesters or only selectively, considering the natural history of the 20 instant diagnoses. Results: Of the 20 instant diagnoses, five involved the central/peripheral nervous system (exencephaly/anencephaly, alobar/semilobar holoprosencephaly, cephalocele, open spinal dysraphism, complete agenesis of corpus callosum), five involved the heart (hypoplastic left heart syndrome, complete atrioventricular septal defect, severe Ebstein's anomaly, critical aortic stenosis, transposition of the great arteries), five involved the abdominal wall (left‐sided congenital diaphragmatic hernia, exomphalos, gastroschisis, body‐stalk anomaly) or gastrointestinal tract (duodenal atresia), and five involved the remaining systems (three urinary (autosomal recessive polycystic kidney disease, multicystic dysplastic kidney, lower urinary tract obstruction), two skeletal (transverse limb defect, radial ray defect)). All of the descriptors were found to identify unequivocally the related malformations, whereas four of the malformations were not associated with their reference descriptors in every case. For example, congenital diaphragmatic hernia (left‐sided) presented without the stomach in the thorax in 42/93 (45.2%) cases. Due to the natural history of the condition, not all signs were recognizable in the first trimester, some becoming evident only from the second trimester onwards. Conclusion: We have defined sonographic descriptors that enable an unequivocal instant diagnosis for a list of 20 major congenital anomalies: the 'INDIAMAN‐20' (INstant DIAgnosis of Major ANomalies) protocol. We believe that using this approach may facilitate focused training of less experienced operators and that it may be incorporated into artificial intelligence and deep learning protocols, further boosting the instant prenatal recognition of these lethal or life‐threatening malformations. © 2022 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

Objectives: To report on the early detection of congenital heart disease (CHD) in low‐ and high‐risk populations managed at our hospital; and perform a detailed analysis of false‐negative diagnoses, in order to derive possible recommendations on how to reduce their incidence. Methods: This was a retrospective observational study analyzing cases which underwent an ultrasound examination at the end of the first trimester at the Fetal Medicine and Surgery Unit of Gaslini Children's Hospital, Genoa, Italy, in the period January 2015 to December 2021. The study population included both low‐risk pregnancies that underwent standard first‐trimester combined screening and high‐risk ones referred to our unit because of a positive combined test or suspicion of fetal anomalies raised in a regional community hospital. For each case, the following variables were retrieved and analyzed: number of fetuses, maternal body mass index, gestational age at first‐trimester screening, whether the pregnancy was low or high risk, nuchal translucency thickness (normal or > 99th centile), type of CHD, associated extracardiac anomalies, karyotype and pregnancy outcome. For low‐risk pregnancies, suspicion of CHD was also recorded. In low‐risk cases, sonographic cardiac screening comprised evaluation of the four‐chamber view (grayscale and color/power Doppler) and three‐vessel‐and‐trachea view (color/power Doppler). High‐risk cases underwent early fetal echocardiography. False‐negative cases were categorized according to likely cause of the missed diagnosis, as follows: human factor; technical factor; acoustic‐window factor. Results: Gestational age at ultrasound ranged from 12 + 0 to 13 + 6 weeks (crown–rump length (CRL), 50.1–84.0 mm) in the low‐risk group and from 11 + 5 to 13 + 6 weeks (CRL, 45.1–84.0 mm) in the high‐risk group. Over the 7‐year study period, 7080 pregnancies were evaluated in the first trimester. Of these, 6879 (7167 fetuses) were low‐risk and 201 were high‐risk cases. In the low‐risk group, there were 30 fetuses with CHD (including 15 major and 15 minor CHD), yielding a prevalence of 4.2/1000 (2.1/1000 for major CHD). Nine of the 30 CHD cases were suspected at screening ultrasound (7/15 major CHD). Excluding cases in which the CHD would not be expected to be associated with a modification of the screening views and would therefore not be detectable on screening ultrasound, 7/12 cases of major CHD were detected, corresponding to a sensitivity of 58.3%. Among the 201 high‐risk cases, there were 46 fetuses with CHD (including 44 major and two minor CHD), of which 43 were detected, corresponding to a sensitivity for early fetal echocardiography of 93.5%, or 97.7% if the two cases that were unlikely to be detectable on first‐trimester screening were excluded. Analysis of the 11 (of 24) false‐negative cases that would be expected to be picked up on screening views revealed that human error (image interpretation and/or scanning approach) was involved in all 11 cases and technical factors (excessive color priority (color‐balance function) and/or incorrect plane alignment) were present in two. There was impairment of the acoustic window (associated with maternal obesity and/or twin gestation) as a cofactor in five of the 11 cases. Conclusions: The sensitivity for detection of major CHD of early cardiac screening in low‐risk pregnancy is under 60%, partly due to the natural history of CHD and, it seems, partly relating to human error and technical issues with image quality. Factors associated with false‐negative diagnoses may be categorized into three types: human error, technical factors and acoustic‐window impairment. We recommend: appropriate assessment with fetal posterior spine; that sufficient time is spent on assessment of the fetal situs; and that color/power Doppler settings are adapted to the individual case. A lower threshold for referring doubtful cases for early fetal echocardiography should be adopted in cases of maternal obesity and in twin gestation. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]