The effectiveness of prenatal serum biomarker screening for neural tube defects in second trimester pregnant women: a meta-analysis

Prenatal diagnosis and postnatal outcome of closed spinal dysraphism

OBJECTIVE

To evaluate the prenatal diagnosis of closed dysraphism (CD) and its correlation with postnatal findings and neonatal adverse outcomes.

METHODS

A retrospective cohort study including pregnancies diagsnosed with fetal CD by prenatal ultrasound (US) and magnetic resonance imaging (MRI) at a single tertiary center between September 2011 and July 2021.

RESULTS

CD was diagnosed prenatally and confirmed postnatally in 12 fetuses. The mean gestational age of prenatal imaging was 24.2 weeks, in 17% the head circumference was ≤fifth percentile and in 25% the cerebellar diameter was ≤fifth percentile. US findings included banana sign in 17%, and lemon sign in 33%. On MRI, posterior fossa anomalies were seen in 33% of cases, with hindbrain herniation below the foramen magnum in two cases. Mean clivus-supraocciput angle (CSA) was 74°. Additional anomalies outside the CNS were observed in 50%. Abnormal foot position was demonstrated prenatally in 17%. Neurogenic bladder was present in 90% of patients after birth.

CONCLUSION

Arnold Chiari II malformation and impaired motor function can be present on prenatal imaging of fetuses with CD and may be associated with a specific type of CD. Prenatal distinction of CD can be challenging. Associated extra CNS anomalies are frequent and the rate of neurogenic urinary tract dysfunction is high.

Fetal and Placental Causes of Elevated Serum Alpha-Fetoprotein Levels in Pregnant Women

The most common association related to alpha-fetoprotein (AFP) is fetal neural tube defect (NTD), and indeed, this is where the international career of this protein began. In times when ultrasonography was not yet technically advanced, the detection of high levels of AFP in maternal serum (MS-AFP) and amniotic fluid was the basis for suspecting neural tube defects. In cases where there was no confirmation of NTD, other causes were sought. It has been established that high titers of MS-AFP could originate in other defects or diseases, such as (1) increased proteinuria in severe fetal kidney diseases; (2) pathological overproduction in liver diseases; (3) penetration through the membranes of gastrointestinal organs exposed to amniotic fluid; (4) passage through the walls of skin vessels; and as a side effect of (5) hepatic hematopoiesis and increased transfer through the edematous placenta in fetal anemia. This article provides a review of the current literature on congenital defects and genetic diseases in the fetus where an elevated level of MS-AFP may serve as the initial diagnostic clue for their detection.

Advances in Fetal Surgical Repair of Open Spina Bifida

Spina bifida remains a common congenital anomaly of the central nervous system despite national fortification of foods with folic acid, with a prevalence of 2-4 per 10,000 live births. Prenatal screening for the early detection of this condition provides patients with the opportunity to consider various management options during pregnancy. Prenatal repair of open spina bifida, traditionally performed by the open maternal-fetal surgical approach through hysterotomy, has been shown to improve outcomes for the child, including decreased need for cerebrospinal fluid diversion surgery and improved lower neuromotor function. However, the open maternal-fetal surgical approach is associated with relatively increased risk for the patient and the overall pregnancy, as well as future pregnancies. Recent advances in minimally invasive prenatal repair of open spina bifida through fetoscopy have shown similar benefits for the child but relatively improved outcomes for the pregnant patient and future childbearing.

Maternal serum alpha-fetoprotein level and the relationship to ventriculomegaly in fetal neural tube defect: A retrospective cohort study

OBJECTIVE

To estimate the significance of the association between mid-trimester maternal serum alpha-fetoprotein (MSAFP) level and fetal neuroanatomic findings in cases of open neural tube defect (ONTD).

METHODS

Retrospective study of patients referred for prenatal ONTD repair between 2012 and 2018. Cases were classified into three groups based on their MSAFP level: 1)High MSAFP (>3.8MoM - n = 22), 2)Moderately high MSAFP (≤3.8 and ≥2.5MoM - n = 28), 3)Normal MSAFP (<2.5MoM - n = 18). MRI scans at the time of referral were used to assess the relationship between MSAFP and: A)Type of ONTD; B) Ventriculomegaly; C) Size of the myeloschisis lesion; D) Volume of myelomeningocele; E) Anatomical level of the lesion (LL).

RESULTS

Having a high MSAFP level was more likely to be associated ventriculomegaly at mid-gestation than a moderately high or normal MSAFP level (OR = 8.4;CI95[0.9-73.4];p = 0.05 and OR = 2.8;CI95[0.9-8.8];p = 0.07). There were no differences between the three groups regarding type of lesion, size of the myeloschisis lesion, anatomic LL, or volume of the myelomeningocele sac. Myeloschisis cases with normal MSAFP had a larger surface area when compared to myeloschisis cases with moderately high MSAFP (219.8[104.4-551] vs 155.4[38.5-502.4] mm², p = 0.04).

CONCLUSION

A 2nd trimester MSAFP level >3.8MoM in a fetus with ONTD is associated with mid-gestation ventriculomegaly.

Imaging findings in association with altered maternal alpha-fetoprotein levels during pregnancy

Maternal serum alpha-fetoprotein is a valuable laboratory test used in pregnant women as an indicator to detect certain clinical abnormalities. These can be grouped into four main categories: fetal factors, pregnancy complications, placental abnormalities, and maternal factors. Imaging is an invaluable tool to investigate the various etiologies leading to altered maternal serum alpha-fetoprotein. By reading this article, the radiologist, sonologist, or other health care practitioner should be able to define the probable pathology leading to the laboratory detected abnormal maternal serum levels, thus helping the clinician to appropriately manage the pregnancy and counsel the patient.

CSF-Based Analysis for Identification of Potential Serum Biomarkers of Neural Tube Defects

The protein composition of cerebrospinal fluid (CSF) in neural tube defects (NTDs) remains unknown. We investigated the protein composition of CSF from 9 infants with NTDs using isobaric tags for relative and absolute quantitation (iTRAQ). We identified 568 proteins in the CSF of infants with spina bifida, which is the most common type of NTD. Among these, 18 proteins were associated with neural tube closure in the CSF during human embryonic neurulation and 5 were involved in NTDs. Based on these results, an animal model was further utilized to investigate early serum biomarkers for NTDs. We found that the myristoylated alanine-rich C-kinase substrate, Kunitz-type protease inhibitor 2, and apolipoprotein B-100 protein levels were decreased in both embryos and the sera of pregnant Sprague-Dawley rats carrying embryos with NTDs. CSF proteins may be useful in the discovery of potential serum biomarkers for NTDs.

Neural tube defects: from a proteomic standpoint

Neural tube defects (NTDs) are congenital birth defects classified according to their resulting morphological characteristics in newborn patients. Current diagnosis of NTDs relies largely on the structural evaluation of fetuses using ultrasound imaging, with biochemical characterization used as secondary screening tools. The multigene etiology of NTDs has been aided by genetic studies, which have discovered panels of genes mutated in these diseases that encode receptors and cytoplasmic signaling molecules with poorly defined functions. Animal models ranging from flies to mice have been used to determine the function of these genes and identify their associated molecular cascades. More emphasis is now being placed on the identification of biochemical markers from clinical samples and model systems based on mass spectrometry, which open novel avenues in the understanding of NTDs at protein, metabolic and molecular levels. This article reviews how the use of proteomics can push forward the identification of novel biomarkers and molecular networks implicated in NTDs, an indispensable step in the improvement of patient management.

Is MSAFP Still a Useful Test for Detecting Open Neural Tube Defects and Ventral Wall Defects in the Era of First-Trimester and Early Second-Trimester Fetal Anatomical Ultrasounds?

Introduction: To evaluate whether maternal serum α-fetoprotein (MSAFP) improves the detection rate for open neural tube defects (ONTDs) and ventral wall defects (VWD) in patients undergoing first-trimester and early second-trimester fetal anatomical survey. Material and Methods: A cohort of women undergoing screening between 2005 and 2012 was identified. All patients were offered an ultrasound at between 11 weeks and 13 weeks and 6 days of gestational age for nuchal translucency/fetal anatomy followed by an early second-trimester ultrasound at between 15 weeks and 17 weeks and 6 days of gestational age for fetal anatomy and MSAFP screening. All cases of ONTD and VWD were identified via query of billing and reporting software. Sensitivity and specificity for detection of ONTD/VWD were calculated, and groups were compared using the Fisher exact test, with p < 0.05 as significance. Results: A total of 23,790 women met the criteria for inclusion. Overall, 15 cases of ONTD and 17 cases of VWD were identified; 100% of cases were diagnosed by ultrasound prior to 18 weeks' gestation; none were diagnosed via MSAFP screening (p < 0.001). First-trimester and early second-trimester ultrasound had 100% sensitivity and 100% specificity for diagnosing ONTD/VWD. Discussion: Ultrasound for fetal anatomy during the first and early second trimester detected 100% of ONTD/VWD in our population. MSAFP is not useful as a screening tool for ONTD and VWD in the setting of this ultrasound screening protocol.

Magnetic resonance imaging in the prenatal diagnosis of neural tube defects

OBJECTIVE

To assess the role of magnetic resonance imaging (MRI) in the prenatal diagnosis of neural tube defects (NTDs).

BACKGROUND

NTDs comprise a heterogeneous group of congenital anomalies that derive from the failure of the neural tube to close. Advances in ultrasonography and MRI have considerably improved the diagnosis and treatment of NTDs both before and after birth. Ultrasonography is the first technique in the morphological study of the fetus, and it often makes it possible to detect or suspect NTDs. Fetal MRI is a complementary technique that makes it possible to clear up uncertain ultrasonographic findings and to detect associated anomalies that might go undetected at ultrasonography. The progressive incorporation of intrauterine treatments makes an accurate diagnosis of NTDs essential to ensure optimal perinatal management. The ability of fetal MRI to detect complex anomalies that affect different organs has been widely reported, and it can be undertaken whenever NTDs are suspected.

CONCLUSION

We describe the normal appearance of fetal neural tube on MRI, and we discuss the most common anomalies involving the structures and the role of fetal MRI in their assessment.

KEY POINTS

• To learn about the normal anatomy of the neural tube on MRI • To recognise the MR appearance of neural tube defects • To understand the value of MRI in assessing NTDs.

Geographic and urban-rural disparities in the total prevalence of neural tube defects and their subtypes during 2006-2008 in China: a study using the hospital-based birth defects surveillance system

BACKGROUND

Previous reports on the prevalence of neural tube defects (NTDs) in China did not include cases of NTDs that were less than 28 weeks of gestational age (GA) and hence did not accurately reflect the total prevalence of NTDs or the geographic and urban-rural disparities in their prevalence. This article includes cases of NTDs that were less than 28 weeks of GA.

METHODS

Data used in this study were collected from 2006 to 2008 using a nationwide hospital-based registry, the Chinese Birth Defects Monitoring Network. The total prevalence ratio (PR) of NTDs and their subtypes, the ratios of PR (PRR), and 95% confidence intervals (CI) were used to analyse geographic disparities at both the regional (north, south) and provincial levels and to analyse disparities between rural and urban areas.

RESULTS

Overall, the total PR of NTDs was 14.0 per 10,000 births. The PRR of NTDs of rural women between the north and south region was 2.26 (95% CI: 2.04-2.52), which was much higher than that of urban women (PRR: 1.56, 95% CI: 1.41-1.72). The three subtypes of NTDs had different geographic distribution at the level of province. The urban-rural PRR of NTDs was 2.14 (95% CI: 1.94-2.34) in the north but only 1.47 (95% CI: 1.31-1.66) in the south.

CONCLUSIONS

There is a high total prevalence of NTDs, which remains one of the major public health concerns in China. Eliminating the geographic and urban-rural disparities in the disease burden is a priority for future intervention.

Providing a primary care medical home for children and youth with spina bifida

The pediatric primary care provider in the medical home has a central and unique role in the care of children with spina bifida. The primary care provider addresses not only the typical issues of preventive and acute health care but also the needs specific to these children. Optimal care requires communication and comanagement with pediatric medical and developmental subspecialists, surgical specialists, therapists, and community providers. The medical home provider is essential in supporting the family and advocating for the child from the time of entry into the practice through adolescence, which includes transition and transfer to adult health care. This report reviews aspects of care specific to the infant with spina bifida (particularly myelomeningocele) that will facilitate optimal medical, functional, and developmental outcomes.

Investigation of ultrasound screening efficiency for neural tube defects during pregnancy in rural areas of China

OBJECTIVES

To understand the uptake and efficacy of ultrasound screening for neural tube defects (NTDs) during pregnancy, and the outcomes when NTDs were detected in rural areas of China.

STUDY DESIGN

Prevalence study.

METHODS

Four hundred and twenty-four women who delivered or gestated babies/fetuses with NTDs were selected at random in 20 counties of two provinces of China from March 2008 to January 2009. The uptake of ultrasound screening, NTD detection rate and termination of pregnancy (TOP) rate were calculated and analyzed. Generalized estimating equations were employed to control for potential confounding factors.

RESULTS

The uptake of ultrasound screening was 98.8%. Among the study subjects, 361 (85.1%) NTDs were detected and 63 (14.9%) were not detected by prenatal ultrasound screening. The total detection rate was 43.3% (15.6%, 49.6% and 52.2% in the first, second and third trimesters, respectively; P < 0.05). Taking the possibility of NTD detection in the first trimester as 1.0, the possibilities in the second and third trimesters were 10.9 [95% confidence interval (CI) 6.5-18.3] and 25.2 (95% CI 13.3-47.6), respectively. The detection rate at the township health centres (THCs), family planning centres (FPCs), maternal and child care service centres (MCSCs) and hospitals was 24.5%, 29.1%, 53.6% and 78.1%, respectively (P < 0.05). Taking the possibility of NTD detection at THCs as 1.0, the possibilities at FPCs, MCSCs and hospitals were 0.9 (95% CI 0.5-1.6), 3.4 (95% CI 1.9-6.1) and 2.1 (95% CI 1.3-3.4), respectively. Three hundred and fifty-five (98.3%) of the 361 NTDs detected at prenatal ultrasound screening ended in TOP.

CONCLUSIONS

The uptake of ultrasound screening was satisfactory, but the NTD detection rate was low. Ultrasound screening did not play its full role in the secondary prevention of NTDs in the study areas. Medical institutions in rural areas in China need to improve their ultrasound screening skills in order to increase the efficacy of NTD control.