Ultrasonographic evaluation of the fetal central nervous system: review of guidelines

Fetal and neonatal outcomes of posterior fossa anomalies: a retrospective cohort study

The primary aim of this study was to estimate the incidence of posterior fossa anomalies (PFA) and assess the associated outcomes in King Abdulaziz Medical City (KAMC), Riyadh. All fetuses diagnosed by prenatal ultrasound with PFA from 2017 to 2021 in KAMC were analyzed retrospectively. PFA included Dandy-Walker malformation (DWM), mega cisterna magna (MCM), Blake's pouch cyst (BPC), and isolated vermian hypoplasia (VH). The 65 cases of PFA were 41.5% DWM, 46.2% MCM, 10.8% VH, and 1.5% BPC. The annual incidence rates were 2.48, 2.64, 4.41, 8.75, and 1.71 per 1000 anatomy scans for 2017, 2018, 2019, 2020, and 2021, respectively. Infants with DWM appeared to have a higher proportion of associated central nervous system (CNS) abnormalities (70.4% vs. 39.5%; p-value = 0.014) and seizures than others (45% vs. 17.9%; p-value = 0.041). Ten patients with abnormal genetic testing showed a single gene mutation causing CNS abnormalities, including a pathogenic variant in MPL, C5orf42, ISPD, PDHA1, PNPLA8, JAM3, COL18A1, and a variant of uncertain significance in the PNPLA8 gene. Our result showed that the most common PFA is DWM and MCM. The autosomal recessive pathogenic mutation is the major cause of genetic disease in Saudi patients diagnosed with PFA.

Normal values of the fronto-occipital relationship in fetuses between 18 and 40 weeks at two maternal fetal medicine units: Bogotá, Colombia

OBJECTIVE

To establish nomograms for linear measurements of the frontal and occipital horns of the lateral ventricle and their relationship, in pregnant patients between 18 and 40 weeks of gestation and having attended 2 units of Maternal Fetal Medicine in Bogotá-Colombia.

METHODOLOGY

A descriptive cross-sectional study with an analytical component was carried out on pregnant patients who utilized the ultrasound services at 2 Maternal-Fetal Medicine units in Bogotá, between 18 and 40 weeks of pregnancy who underwent measurement. From the anterior and posterior horns of the lateral ventricles, the fronto-occipital ratio was calculated at each gestational week, and nomograms were created for each of these variables.

RESULTS

Nine hundred and seventy-eight patients were included in the study. The distance of the frontal horns ranged between 6.9 and 51.6 mm with a mean of 19.1 ± 5.8 mm; that of the occipital horns had a measurement between 8.7 and 53 mm with a mean of 28, 1 ± 8.9 mm; on the other hand, the fronto-occipital ratio (FOR) yielded a mean of 0.365 ± 0.067 (0.136-0.616) without bearing any relation to gestational age. The trend of normal values for the studied population is displayed, plotted in percentile curves and nomograms for each gestational age.

CONCLUSION

The measurement of the frontal and occipital horns, and the calculation of the fronto-occipital relationship is technically possible between 18 and 40 weeks, finding that the anterior and posterior horns have a positive linear relationship with gestational age. Contrarily, the FOR does not correlate with the gestational age, it was possible to establish a table of percentiles that allows determining the normal values for these measurements during pregnancy.

Fetal neurosurgery

Among fetal surgical procedures, neurosurgery stands out due to the number of cases and the possibility of developing new procedures that can be performed in the fetal period. To perform fetal neurosurgical procedures, there is a need for specialized centers that have experts in the diagnosis of fetal pathologies and a highly complex obstetrics service with specialized maternal-fetal teams associated with a pediatric neurosurgery center with expertise in the diverse pathologies of the fetus and the central nervous system that offers multidisciplinary follow-up during postnatal life. Services that do not have these characteristics should refer their patients to these centers to obtain better treatment results. It is essential that the fetal neurosurgical procedure be performed by a pediatric neurosurgeon with extensive experience, as he will be responsible for monitoring these patients in the postnatal period and for several years. The objective of this manuscript is to demonstrate the diagnostic and treatment possibilities, in the fetal period, of some neurosurgical diseases such as hydrocephalus, tumors, occipital encephalocele, and myelomeningocele.

A meta-analysis of pregnancy outcomes in the diagnosis of isolated foetal renal parenchyma by prenatal ultrasonography

BACKGROUND

To effectively circumvent foetal structural abnormalities and serious newborn sequelae, antenatal ultrasound evaluation can support making an early diagnosis for potential prenatal management or the termination of pregnancy.

OBJECTIVE

This study systematically evaluated a meta-analysis of different pregnancy outcomes in the diagnosis of isolated foetal renal parenchymal echogenicity (IHEK) by prenatal ultrasonography.

METHODS

Two researchers conducted a literature search following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The following databases were included in the search: China National Knowledge Infrastructure, Wanfang Medical Network, China Academic Journals Full-text Database, PubMed, Web Of Science and Springer Link; additional library websites were also included, and the search reviewed different pregnancies among patients with IHEK. The outcome indicators were the live birth rate, the incidence of polycystic renal dysplasia and the incidence of pregnancy termination/neonatal death. The meta-analysis was performed using the Stata/SE 12.0 software.

RESULTS

A total of 14 studies were included in the meta-analysis (total sample content, 1,115 cases). The combined effect size of prenatal ultrasound diagnosis of pregnancy termination/neonatal mortality in patients with IHEK was 0.289 (confidence interval (CI) 95%; range, 0.102-0.397). The combined effect size of the live birth rate of pregnancy outcomes was 0.742 (CI 95%; range, 0.634-0.850. The combined effect size of the polycystic kidney dysplasia rate was 0.066 (CI 95%; range, 0.030-0.102). The heterogeneity of all three results was > 50%; accordingly, a random-effects model was used.

CONCLUSION

The indications for eugenic labour should not be included in a prenatal ultrasound diagnosis of patients with IHEK. In the results of this meta-analysis, the live birth and polycystic dysplasia rates were optimistic in terms of pregnancy outcomes. Therefore, under the condition of excluding other unfavourable factors, it is necessary to A thorough technical inspection is required to make an accurate judgment.

Measurement of the Area and Circumference of the Leg: Preliminary Results of a New Method for Estimating Leg Muscle Trophism in Fetuses With Open Lumbosacral Spina Bifida

OBJECTIVE

To standardize a new technique to evaluate the fetal leg muscle trophism by measuring the area and circumference, and comparing this technique between normal and fetuses with open lumbosacral spina bifida (SB).

METHODS

Observational cross-sectional study was carried out on pregnant women with 26 weeks who were divided into two groups: Group I-fetuses with diagnosis of open lumbosacral SB; Group II-normal fetuses (control). In fetuses with SB, subjective evaluation of the lower limbs was performed (muscle echogenicity and leg movements). To estimate the leg muscle trophism, the measurement of the area and circumference of the leg were standardized, and the reproducibility of this method was performed.

RESULTS

Thirty-one fetuses with open lumbosacral SB and 51 normal fetuses were evaluated. The measurements of the area and circumference of the leg proved to be highly reproducible (intraclass correlation coefficient-ICC > 0.95). The leg area and circumference measurements were statistically lower in the SB group than in the control group (p < .001). When subjective ultrasound assessment demonstrated hypotrophy of the lower limbs, the measurements of the area and circumference of the leg were statistically lower when compared to normal fetuses (p < .001). Fetuses with open SB with abnormal lower limb movements had lower measurements of the area and circumference of the leg than fetuses with normal movements (p < .001).

CONCLUSION

A new technique for estimating fetal leg muscle trophism was standardized, which proved to be highly reproducible and was able to show the difference between normal and fetuses with SB.

Pregnant women infected by the Zika virus: Ultrasound findings and growth patterns of fetuses with and without microcephaly

OBJECTIVE

To compare ultrasound growth measurements of fetuses with and without microcephaly in suspected Zika virus infection.

METHODS

A retrospective cohort study included pregnant women with suspected Zika virus infection to evaluate 110 fetuses with and without microcephaly. The women had been admitted to the fetal medicine unit between October 2015 and August 2016. Cases of fetal microcephaly resulting from other causes were excluded. Variables evaluated were the ultrasound measurements taken at fetal biometry. The relation between each fetal biometry measurement and gestational age was analyzed using fractional polynomials in random-effects regression models. To evaluate fetal growth, curves of the mean fetal biometric parameters were constructed as a function of gestational age.

RESULTS

Mean biparietal diameter and mean head circumference increased in both groups as a function of gestational age. In the group with fetal microcephaly, mean head circumference was significantly larger in the 13th and 14th weeks of pregnancy, becoming smaller compared with the group without microcephaly from the 20th week onwards, with the difference increasing with gestational age.

CONCLUSION

Fetal head circumference continues to increase until birth, even after a diagnosis of microcephaly, with a reduction only in the pace of growth. Growth decelerates as the pregnancy approaches term.

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.