Abnormalities of the Fetal Central Nervous System: Prenatal US Diagnosis with Postnatal Correlation.

Fetal central nervous system (CNS) abnormalities are second only to cardiac malformations in their frequency of occurrence. Early and accurate diagnosis at prenatal US is therefore essential, allowing improved prenatal counseling and facilitating appropriate referral. Thorough knowledge of normal intracranial anatomy and adoption of a logical sonographic approach can improve depiction of abnormal findings, leading to a more accurate differential diagnosis earlier in pregnancy. Four standard recommended views-transventricular, falx, cavum, and posterior fossa or transcerebellar views-provide an overview of fetal intracranial anatomy during the second trimester anatomy scan. Essential elements surveyed in the head and neck include the lateral cerebral ventricles, choroid plexus, midline falx, cavum septi pellucidi, cerebellum, cisterna magna, upper lip, and nuchal fold. CNS abnormalities can be organized into six main categories at prenatal US. Developmental anomalies include neural tube defects and neuronal migration disorders. Posterior fossa disorders include Dandy-Walker malformation variants and Chiari II malformation. Ventricular anomalies include aqueductal stenosis. Midline disorders include those on the spectrum of holoprosencephaly, agenesis of the corpus callosum, and septo-optic dysplasia. Vascular anomalies include vein of Galen malformations. Miscellaneous disorders include hydranencephaly, porencephaly, tumors, and intracranial hemorrhage. Correlation with postnatal MRI is helpful for confirmation and clarification of suspected diagnoses after birth. The authors discuss a standard US imaging approach to the fetal CNS and review cases in all categories of CNS malformations, providing postnatal MRI correlation when available.©RSNA, 2020.

Transabdominal Fetal Ultrasound Before Early-Term Planned Delivery for Norrie Disease.

Purpose: To describe a case of early-term planned delivery of a fetus with Norrie disease. Methods: A retrospective chart review was performed. Results: A fetus with an older sibling with bilateral blindness from Norrie disease had positive NPD genetic testing on chorionic villus sampling. Transabdominal fetal ophthalmic ultrasound found bilateral total retinal detachments (RDs) at 32 weeks gestational age. The fetus was delivered at 37 weeks and had an examination under anesthesia, which showed bilateral inoperable RDs. Conclusions: Transabdominal fetal ophthalmic ultrasound was able to identity bilateral total RDs in utero. Further study is warranted on preterm or early-term delivery if a fetus has evidence of RD in utero.

Validation of a sonographic checklist for the detection of histologic placenta accreta spectrum.

BACKGROUND: To standardize research terminology and to reduce unanticipated placenta accreta spectrum, the European Working Group for Abnormally Invasive Placenta developed a consensus checklist for reporting suspected placenta accreta spectrum observed during an antenatal ultrasound. The diagnostic accuracy of the European Working Group for Abnormally Invasive Placenta checklist has not been assessed. OBJECTIVE: This study aimed to test the performance of the European Working Group for Abnormally Invasive Placenta sonographic checklist in predicting histologic placenta accreta spectrum. STUDY DESIGN: This was a multisite, blinded, retrospective review of transabdominal ultrasound studies performed between 26 to 32 weeks' gestation for subjects with histologic placenta accreta spectrum between 2016 and 2020. We matched a control cohort of subjects without histologic placenta accreta spectrum in a 1:1 ratio. To reduce reader bias, we matched the control cohort for known risk factors including previa, number of previous cesarean deliveries, previous dilation and curettage, in vitro fertilization, and clinical factors affecting image quality including multiple gestation, body mass index, and gestational age at the ultrasound. Nine sonologists from 5 referral centers, blinded to the histologic outcomes, interpreted the randomized ultrasound studies using the European Working Group for Abnormally Invasive Placenta checklist. The primary outcome was the sensitivity and specificity of the checklist to predict placenta accreta spectrum. Two separate sensitivity analyses were performed. First, we excluded subjects with mild disease (ie, only assessed subjects with histologic increta and percreta). Second, we excluded interpretations from the 2 most junior sonologists. RESULTS: A total of 78 subjects were included (39 placenta accreta spectrum, 39 matched control). Clinical risk factors and image quality markers were statistically similar between the cohorts. The checklist sensitivity (95% confidence interval) was 76.6% (63.4-90.6) and the specificity (95% confidence interval) was 92.0% (63.4-99.9) with a positive and negative likelihood ratio of 9.6 and 0.3, respectively. When we excluded subjects with mild placenta accreta spectrum disease, the sensitivity (95% confidence interval) increased to 84.7% (73.6-96.4) and the specificity was unchanged at 92.0% (83.2-99.9). Sensitivity and specificity were unchanged when the interpretations from the 2 most junior sonologists were excluded. CONCLUSION: The 2016 European Working Group for Abnormally Invasive Placenta checklist for interpreting placenta accreta spectrum has a reasonable performance in detecting histologic placenta accreta spectrum and excluding cases without placenta accreta spectum.

Can we improve the gestation-adjusted projection (GAP) method for prediction of birth weight in morbidly obese women?

Objective: The gestation-adjusted projection (GAP) is a method to predict birthweight using population birth data and third trimester ultrasound fetal weight. This method usually utilizes population birth weight data from almost 40 years ago. In 2011, a large cohort of racially diverse infants across the US was included to validate updated birth curves. Our objective was to determine if the updated data would improve the accuracy of the GAP method during the third trimester among obese women. Methods: This secondary analysis of a cohort study included singleton pregnancies of obese women who had fetal growth assessment(s) in the third trimester. The first subgroup (N = 235) included women with a BMI >40 kg/m2 who had ultrasounds during 30 + 0-35 + 0 weeks (EARLY) and greater than 35 + 0 weeks (LATE). The second subgroup (N = 431) included women with a BMI 30-35, 40-50, or >50 kg/m2 who had an ultrasound during 34 + 0-36 + 6 weeks. Mean absolute percent error was calculated for all GAP methods and compared using paired t-tests. Sensitivity, specificity, and area under the curve for diagnosis of birth weight >4000 grams were also estimated for each GAP method. Results: The mean absolute percent error for the first subgroup (N = 235) using historical population birth weights was 7.4-7.9%. After using updated population birth weight curves using all neonates, the mean absolute percent error for the first subgroup ranged between 7.6 and 9.4%. GAP predictions using all neonates, as well as male and female-specific birth data compared to the historical population data during both the EARLY and LATE periods were significantly worse (p < .01). The mean absolute percent error for the second subgroup (N = 431) using historical population birth weights ranged from 7.2 to 7.9%. The absolute percent error using gender-specific compared to historical data was significant in the BMI 30-35 group (male 8.1% versus historical 7.6%, p < .01, female 8.1% versus historical 7.6%, p < .01). The differences in absolute percent error between historical and updated population data became less evident in the BMI 40-50 and >50-kg/m2 groups (p = .05 and p = .15, respectively) though still overall performed worse with the updated data. Conclusions: Prediction of birth weight using the GAP method does not seem to be improved among obese women after using updated population data. Alternatively, modeling techniques may need to be applied to improve the accuracy of the GAP method.

Pharmacologic Treatment of Diabetes in Pregnancy.

IMPORTANCE: Diabetes affects 6% to 9% of pregnancies, with gestational diabetes mellitus accounting for more than 90% of cases. Pregestational and gestational diabetes are associated with significant maternal and fetal risks; therefore, screening and treatment during pregnancy are recommended. Recommendations regarding the preferred treatment of diabetes in pregnancy have recently changed, with slight differences between American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) recommendations. OBJECTIVE: Our review discusses the diagnosis, management, and treatment of pregestational and gestational diabetes with the oral hypoglycemic agents metformin and glyburide as well as insulin. We also review the evidence for the safety and efficacy of these medications in pregnancy. EVIDENCE ACQUISITION: Articles were obtained from PubMed, the ACOG Practice Bulletin on Gestational Diabetes Mellitus, and the SMFM statement on the pharmacological treatment of gestational diabetes. RESULTS: Insulin does not cross the placenta and has an established safety profile in pregnancy and is therefore considered a first-line treatment for gestational diabetes. Metformin and glyburide have also been shown to be relatively safe in pregnancy but with more limited long-term data. Regarding maternal and fetal outcomes, metformin is superior to glyburide and similar to insulin. CONCLUSIONS AND RELEVANCE: Insulin is the preferred pharmacologic treatment according to ACOG. However, SMFM has stated that outcomes with metformin are similar, and it may also be considered as first-line therapy. Both agree that the available data show that metformin is safer and superior to glyburide, and glyburide is no longer recommended as a first-line therapy for the treatment of gestational diabetes.

Sonohysterography: do 3D reconstructed images provide additional value?

OBJECTIVE: The purpose of this study was to retrospectively determine the value of adding 3D multiplanar sonography to 2D sonohysterography. MATERIALS AND METHODS: Between September 2003 and April 2005, 80 women (mean age, 43.5 years; range, 26-78 years) underwent sonohysterography with both conventional 2D sonohysterography and 3D multiplanar imaging (volume of data acquired and reconstructed in the transverse, sagittal, and coronal planes). Three blinded readers interpreted the 2D scans alone and then the 2D and 3D images together. Visualization of endometrial abnormality (polyps, fibroids, or septations) and definition of fundal contour were scored by each reader on a three-point scale (1, visualized; 2, unsure; 3, not visualized). Wilcoxon's signed rank test was used to assess mean differences between findings. Reader agreement was determined with the kappa statistic. Pathologic correlation was performed when the findings were available. RESULTS: Average (mean +/- SD) reader scores for identification of endometrial abnormality were not significantly different: 1.70 +/- 0.91 for 2D alone versus 1.69 +/- 0.92 for 2D and 3D combined (p = 0.38). There also was no significant difference when polyps (2.14 +/- 0.90 vs 2.12 +/- 0.93), fibroids (2.57 +/- 0.79 vs 2.53 +/- 0.82), and septations (2.88 +/- 0.39 vs 2.87 +/- 0.42) were evaluated separately. Average scores for definition of fundal contour were significantly (p < 0.0001) different (2.93 +/- 0.34 for 2D alone versus 1.45 +/- 0.80 for 2D and 3D combined). Agreement between readers was found with average kappa values of 0.72 for 2D alone and 0.78 for 2D and 3D. For the 42 subjects for whom pathologic findings were available, readers identified 92% of the abnormalities. CONCLUSION: Three-dimensional reformations improve visualization of the uterine fundus and aid in identification or exclusion of a fundal contour abnormality but do not add value in the detection of endometrial abnormalities.

Ultrasound Examination of the Fetal Heart.

Congenital heart disease (CHD) occurs in 4-13 per 1000 births in the United States. While many risk factors for CHD have been identified, more than 90% of cases occur in low-risk patients. Guidelines for fetal cardiac screening during the second trimester anatomy ultrasound have been developed by the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) in order to improve antenatal detection rates and to standardize the fetal cardiac screening examination. Patients found to be at increased risk of CHD because of risk factors or an abnormal screening examination should be referred for second trimester fetal echocardiography. Recently, 3D and 4D ultrasound techniques are being utilized to enhance detection rates and to better characterize cardiac lesions, and several first trimester ultrasound screening markers have been proposed to identify patients at increased risk of CHD. However, detection rates have not improved significantly due to limitations such as cost, access, and training that are associated with new technologies and screening methods. The most cost effective way to improve detection rates of CHD may be to standardize screening protocols across practices according to established guidelines and to have a low threshold for referral for fetal echocardiography.

Dichorionic, diamnionic twin pregnancy discordant for anencephaly: Report of two cases and literature review.

Anencephaly is a lethal diagnosis. In the unique situation of a twin pregnancy discordant for anencephaly, early ultrasound diagnosis based on the discrepancy in the appearance of the heads can facilitate management and potentially decrease morbidity and mortality for the unaffected twin. We report two such cases of dichorionic, diamniotic twin pregnancies and provide a review of the literature.

Trisomy 8 mosaicism: selective growth advantage of normal cells vs. growth disadvantage of trisomy 8 cells.

A fetus with trisomy 8 mosaicism was identified prenatally due to an abnormal maternal serum triple screen. Tissue samples were taken at birth to determine the level of trisomy 8 mosaicism found within embryonic and extra-embryonic tissues, rates of cell division for the two cell lines, and the effect of mosaicism on the phenotype. The level of trisomy 8 cells in blood and fibroblasts was higher than in placental tissue. Cell cycle kinetics, by incorporation of bromodeoxyuridine for 48 hr, was not significantly different between the trisomy 8 and normal cells for blood or amnion. Fluorescent in situ hybridization (FISH) using centromeric probe for chromosome 8 showed significantly more trisomy 8 in interphase vs. metaphase in lymphoblasts, umbilical cord fibroblasts, and chorion. The loss of trisomy 8 cells is not due to anaphase lag, as determined by micronuclei analysis. The similarity of cell cycle kinetics between trisomy 8 cells and normal diploid cells suggests some trisomy 8 cells are exiting the cell cycle prematurely. This growth disadvantage of trisomy 8 cells results in the appearance of growth advantage for diploid cells.

MR imaging findings in fetal goiter caused by maternal graves disease.

Antenatal diagnosis of fetal goiter should be appropriately managed to avoid perinatal complications. Here, we present the MR imaging features of a fetal goiter caused by maternal Graves disease. Diffusely enlarged fetal thyroid gland was seen showing homogeneously elevated signal on T1-weighted images and intermediate signal on T2-weighted images. To our knowledge, this is the first MR imaging documentation of fetal goiter.