Prospective detection of open spina bifida at 11-13 weeks by assessing intracranial translucency and posterior brain

Impact of choroid plexus size in prenatal diagnosis of normal and abnormal closure of fourth ventricle

OBJECTIVE

To assess the role of the choroid plexus (CP) of the fourth ventricle (4V) in fetuses with an open 4V and a normal cerebellar vermis.

METHODS

Two groups of patients were recruited in two fetal medicine referral centers. The prospectively collected control group included singleton pregnancies with a normal sonographic examination after first-trimester combined screening for chromosomal abnormalities and normal outcome, recruited in the period between 2019 and 2022. The study group was selected retrospectively by searching our databases to identify all cases with an isolated open 4V and normal anatomy and size of the cerebellar vermis. The inclusion criteria of the study group were: (1) gestational age between 20 and 22 weeks; (2) a brainstem-vermis angle ≥ 18° in the midsagittal plane with an otherwise normal cerebellum and vermis; (3) 4V-CP visible and seen separately from the vermis; (4) absence of other intra- and extracranial anomalies; and (5) available prenatal and/or postnatal magnetic resonance imaging (MRI) data.

RESULTS

In 169 cases of the control group, the 4V-CP was seen separately from the cerebellar vermis and was noticed to progressively fill the space caudal to the 4V, between the vermis and brainstem. From 12 to 22 weeks, the surface areas of the vermis and medial portion of the 4V-CP increased progressively with advancing gestation (P < 0.0001). Intra- and interobserver correlation analysis showed good reproducibility for the measurements. Among the cases with an open 4V and a normal vermis, it was retrospectively feasible to visualize the 4V-CP separately from the inferior part of the vermis in 41 fetuses. In five of these cases, the open 4V was due to a small CP. In all 41 fetuses, the diagnosis on MRI was isolated upward rotation of the cerebellar vermis, and no additional anomaly was found.

CONCLUSIONS

Closure of the 4V is dependent on the 4V-CP and not only the cerebellar vermis. In fact, a small CP may represent another cause of an open 4V. Therefore, separate visualization of the 4V-CP and cerebellar vermis is crucial to improve discrimination between the different causes of an open 4V at the anomaly scan and its clinical implications. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Qualitative and quantitative study of fetal posterior fossa during the first trimester in a Chinese population

Background

To establish the normal reference ranges for parameters related to the fetal posterior fossa in the first trimester (11 ~ 13+6 weeks of gestation) and to analyze the relationship between them and crown-rump length (CRL) among the Chinese population.

Methods

Singleton pregnancies of 11 ~ 13⁺⁶ weeks (CRL:45 ~ 84 mm) with both parents from China were randomly selected from January 2021 to November 2021. The related parameters of the posterior fossa including cisterna magna (CM), intracranial translucency (IT), brain stem (BS), brain stem to the occipital bone (BSOB), and brain stem/brain stem to occipital bone (BS/BSOB) were evaluated and measured in nuchal translucency (NT) mid-sagittal section clearly by an experienced sonographer (operator 1). To assess the reproducibility of the measurements, we randomly selected 50 pregnant women. According to the blind method, operators 1 and 2 respectively screened and measured relevant parameters. In addition, operator 1 examined and measured relevant parameters again 2 h after the first.

Results

This study included 1663 fetuses. All fetuses can clearly show the three spaces of the fetal posterior fossa. The ICCs (95% CI) of intra-operator reproducibility of CM, IT, BS, BSOB, BS/BSOB were 0.981 (0.952 ~ 0.991, P < 0.001), 0.929 (0.866 ~ 0.961, P < 0.001), 0.970 (0.946 ~ 0.983, P < 0.001), 0.991 (0.974 ~ 0.996, P < 0.001), 0.939 (0.892 ~ 0.965, P < 0.001), respectively; The ICCs (95% CI) of inter-operator reproducibility 0.926 (0.860 ~ 0.960, P < 0.001), 0.810 (-0.083 ~ 0.940, P < 0.001), 0.820 (0.645 ~ 0.904, P < 0.001), 0.804 (0.656 ~ 0.888, P < 0.001), 0.772 (0.599 ~ 0.871, P < 0.001), respectively. There was a linear correlation between CRL and the parameters related to the posterior fossa (CM, IT, BS, BSOB, BS/BSOB). CM (mm) = -1.698 + 0.532 × CRL (cm) (r = 0.829, P < 0.001); IT (mm) = 0.701 + 0.179 × CRL (cm) (r = 0.548, P < 0.001); BS (mm) = 0.403 + 0.349 × CRL (cm) (r = 0.716, P < 0.001); BSOB (mm) = -0.277 + 0.719 × CRL (cm) (r = 0.829, P < 0.001); BS/BSOB = 0.747—0.021 × CRL (cm) (r = 0.196, P < 0.001).

Conclusions

Qualitative and quantitative assessment of the fetal posterior fossa structure was feasible in the first trimester. We constructed the normal reference ranges of CM, IT, BS, BSOB, and BS/BSOB. Furthermore, CM, IT, BS, and BSOB were positively correlated with CRL, but BS/BSOB was negatively correlated with CRL.

The importance of first trimester screening of cranial posterior fossa in predicting posterior fossa malformations which may be identified in the following weeks of gestation

PURPOSE

We aimed to investigate the value of posterior fossa ultrasonography measurements in predicting fetal posterior fossa anomaly at 11-14 weeks of gestation.

METHODS

The study was performed at Zeynep Kamil Women and Children's Diseases Training and Research Hospital. Measurements were made in two groups: the control group consisted of 328 fetuses with normal postnatal outcome and the study group consisted of 22 fetuses with enlarged 4^th ventricle. In the study group, we questioned the value of intracranial translucency (IT) and brainstem (BS) measurements and the BS/brainstem-to-occipital bone (BSOB) ratio in order to predict possible posterior fossa anomalies that may be identified in advanced gestational weeks. The differences of ultrasonographic measurements between groups with p < 0.05 were considered statistically significant.

RESULTS

IT value, BSOB value, and BS/BSOB ratio were determined as ultrasonographic variables in predicting normal development of the fetal posterior fossa, with cutoff values of 2.7, 5.1, and 0.3. Negative predictive values of these three measurements for posterior fossa abnormalities were 100%. There was no statistically significant difference between the three variables for other diagnostic accuracy values (specifities and positive predictive values) (p > 0.05).

CONCLUSION

IT, BSOB, and BS/BSOB ratio can be used as ultrasonographic markers to predict the normal development of the fetal posterior fossa.

Position of the choroid plexus of the fourth ventricle in first- and second-trimester fetuses: a novel approach to early diagnosis of cystic posterior fossa anomalies

OBJECTIVE

To describe the sonographic appearance and position of the choroid plexus of the fourth ventricle (4V-CP) between 12 and 21 weeks' gestation in normal fetuses and in fetuses with Dandy-Walker malformation (DWM) or Blake's pouch cyst (BPC).

METHODS

The study population comprised 90 prospectively recruited normal singleton pregnancies and 41 pregnancies identified retrospectively from our institutional database that had a suspected posterior fossa anomaly at 12-13 weeks' gestation based on the ultrasound finding of abnormal hindbrain spaces. In all cases the final diagnosis was confirmed by prenatal and/or postnatal magnetic resonance imaging or postmortem examination. All pregnancies underwent a detailed ultrasound assessment, including a dedicated examination of the posterior fossa, at 12-13 weeks, 15-16 weeks and 20-21 weeks of gestation. Two-dimensional ultrasound images of the midsagittal and coronal views of the brain through the posterior fontanelle and three-dimensional volume datasets were obtained. Multiplanar orthogonal image correlation with volume contrast imaging was used as the reference visualization mode. Two independent operators, blinded to the fetal outcome, were asked to classify the 4V-CP as visible or not visible in both normal and abnormal cases, and to assess if the 4V-CP was positioned inside or outside the cyst in fetuses with DWM and BPC.

RESULTS

Of the 41 fetuses with apparently isolated cystic posterior fossa anomaly in the first trimester, eight were diagnosed with DWM, 29 were diagnosed with BPC and four were found to be normal in the second trimester. The position of the 4V-CP differed between DWM, BPC and normal cases in the first- and second-trimester ultrasound examinations. In particular, in normal fetuses, no cyst was present and, in the midsagittal and coronal planes of the posterior fossa, the 4V-CP appeared as an echogenic oval-shaped structure located inside the 4V apparently attached to the cerebellar vermis. In fetuses with DWM, the 4V-CP was not visible in the midsagittal view because it was displaced inferolaterally by the cyst. In contrast, in the coronal view of the posterior brain, the 4V-CP was visualized in all cases with DWM at 12-13 weeks, with a moderate decrease in the visualization rate at 15-16 weeks (87.5%) and at 20-21 weeks (75%). In the coronal view, the 4V-CP was classified as being outside the cyst in all DWM cases at 12-13 weeks and in 87.5% and 75% of cases at 15-16 and 20-21 weeks, respectively. In fetuses with BPC, the 4V-CP was visualized in all cases in both the midsagittal and coronal views at 12-13 weeks and in 100% and 96.6% of cases, respectively, at 15-16 weeks. In the coronal view, the 4V-CP was classified as being inside the cyst in 28 (96.6%), 27 (93.1%) and 25 (86.2%) cases at 12-13, 15-16 and 20-21 weeks, respectively. The medial segment of the 4V-CP was visualized near the inferior part of the vermis.

CONCLUSIONS

Our study shows that longitudinal ultrasound assessment of the 4V-CP and its temporal changes from 12 to 21 weeks is feasible. The 4V-CP is located inside the cyst, just below the vermis, in BPC and outside the cyst, inferolaterally displaced and distant from the vermian margin, in DWM, consistent with the pathogenesis of the two conditions. The position of the 4V-CP is a useful sonographic marker that can help differentiate between DWM and BPC as early as in the first trimester of pregnancy. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Screening for Open Spina Bifida in a Routine Clinical Setting at the First-Trimester Scan: A Prospective Multicentre Cohort Study

OBJECTIVE

The aim of this study was to investigate the performance of screening for open spina bifida (OSB) integrated into the routine first-trimester screening.

METHOD

This is a prospective multicentre study of 4,755 women undergoing first-trimester ultrasound scans over a 4-year period. Measurements of the brainstem (BS) diameter and brainstem-to-occipital-bone (BSOB) distance were performed. The cisterna magna (CM) was measured in the tilted axial view.

RESULTS

Pregnancy outcome data were available for 4,658 fetuses included in this study. There were 5 fetuses with OSB, and in all of them, the BS/BSOB ratio and the CM measurements were abnormal. The sensitivity and specificity of a BS/BSOB ratio >1 were 100%. The sensitivity of a CM width <5th centile was 100%, and the specificity was 95.1%. In 4.6% of cases, the BS/BSOB ratio was between the 95th percentile and 1. In 87.1% of these cases, the CM was normal, and 12.9% had a CM below the 5th percentile.

CONCLUSION

Screening for OSB is feasible in routine first-trimester scans. The BS/BSOB ratio shows a very good sensitivity and specificity. In cases with near-normal values for the BS/BSOB ratio, the CM width might be helpful for further assessment.

Fetal Open and Closed Spina Bifida on a Routine Scan at 11 Weeks to 13 Weeks 6 Days

OBJECTIVES

This study aimed to determine the sensitivity of a first-trimester routine scan in detecting spina bifida (SB) and evaluating the first-trimester intracranial signs.

METHODS

This retrospective study was a review of a prospectively collected database. All cases of SB diagnosed in a tertiary center from 2008 to 2015 were identified. The ultrasound images and medical records were reviewed. All cases of SB diagnosed prenatally were confirmed at birth or autopsy.

RESULTS

A total of 24 cases of SB were diagnosed from 53,349 pregnancy cases. Except for 10 cases with a body stalk anomaly, craniorachischisis, or iniencephaly, 7 cases with open spina bifida (OSB) and 7 cases with closed spina bifida (CSB) were analyzed. The first-trimester detection rates were 100% (7 of 7) for OSB and 28.5% (2 of 7) for CSB. Eight cases were highly suspected of SB in the first trimester because of an abnormal appearance of the posterior brain; 3 were false-positive cases. Two isolated cases of OSB had first-trimester intracranial signs. An obliterated cisterna magna (CM) showed the highest sensitivity for OSB but low specificity. Two cases of OSB had no discernible landmark of intracranial translucency and the CM, and 4 showed normal intracranial translucency with an obliterated CM. All CSB cases were coupled with a normal hind brain except for 2 cases.

CONCLUSIONS

A first-trimester routine scan has high sensitivity in screening for OSB. The CM may be the most sensitive intracranial sign.

First-trimester fetal neurosonography: technique and diagnostic potential

Most brain abnormalities are present in the first trimester, but only a few are detected so early in gestation. According to current recommendations for first-trimester ultrasound, the fetal head structures that should be visualized are limited to the cranial bones, the midline falx and the choroid-plexus-filled ventricles. Using this basic approach, almost all cases of acrania, alobar holoprosencephaly and cephalocele are detected. However, the majority of other fetal brain abnormalities remain undiagnosed until the midtrimester. Such anomalies would be potentially detectable if the sonographic study were to be extended to include additional anatomic details not currently included in existing guidelines. The aim of this review article is to describe how best to assess the normal fetal brain by first-trimester expert multiplanar neurosonography and to demonstrate the early sonographic findings that characterize some major fetal brain abnormalities. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Accuracy of qualitative and quantitative cranial ultrasonographic markers in first-trimester screening for open spina bifida and other posterior brain defects: a systematic review and meta-analysis

BACKGROUND

The significant number of qualitative and quantitative ultrasound markers described for first-trimester screening of open spina bifida (OSB) and other posterior brain defects (oPBD) has resulted in their complex implementation and interpretation for a widespread screening and in a lack of consensus regarding diagnostic accuracy.

OBJECTIVES

To assess and compare the accuracy of qualitative and quantitative cranial sonographic markers at 11-14 weeks of gestation for the detection of OSB and oPBD.

SEARCH STRATEGY

A systematic literature search was performed in MEDLINE and COCHRANE from 2009 to April 2020.

SELECTION CRITERIA

Studies assessing the diagnostic accuracy of quantitative and/or qualitative ultrasound signs to predict OSB and oPBD were included. Cohort studies and case-control studies were also considered.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed the risk of bias. The overall pooled estimate and a summary receiver operating characteristic curve was estimated for each subgroup (qualitative and quantitative assessment).

MAIN RESULTS

Twenty-three studies were included in our meta-analysis. The pooled sensitivity and specificity for qualitative assessment were 76.5% and 99.6%, and for quantitative assessment were 84.5% and 96.3%, respectively; specificity for the qualitative ultrasound signs was significantly higher (P = 0.001). The overall sensitivity of cranial sonographic markers for the screening of oPBD was 76.7% and specificity was 97.5%.

CONCLUSIONS

The qualitative approach demonstrated greater specificity, so this would appear to be more appropriate for daily screening, as a first-line tool, whereas the quantitative approach should be reserved for expert ultrasound.

TWEETABLE ABSTRACT

This study highlights the relevance of first-trimester qualitative ultrasound signs in the screening of open spina bifida.

First trimester cerebral appearance in the presence of closed spina bifida with myelomeningocele, part of the oeis complex

Our communication presents a prenatally detected case with severe spinal defect detected in the first trimester of pregnancy, accompanied by a large skin-covered myelomeningocele but normal cranio-cerebral structural appearance.These findings suggest that in the first trimester, the extent of the spinal defect, the cerebrospinal fluid leakage to a large, but skin-covered, meningocele and fixation of the spinal cord at the lesion are not sufficient to determine downward hindbrain displacement and the development of secondary signs for open spina bifida.Therefore, we suggest a careful evaluation of the fetal cerebral features if a meningocele is detected. The presence of the skin covering the lesion may not be evident in the first trimester, but the absence of intracranial open spina bifida markers may indicate a 'closed' spinal defect, which generally associates a good neurological outcome. Also, studies aimed to investigate the accuracy of the intracranial features for open spina bifida detection should consider the possibility of 'closed' myelomeningoceles to avoid incorrect correlations.

Posterior fossa assessment in the axial view of the head at 11-14 weeks of gestation in normal and aneuploid fetuses

Posterior fossa ultrasound appearance may offer clues for brain anomalies as early as the first trimester. The purpose of the study was to find an easy, reproducible method to examine the posterior fossa. From January 2017 to March 2018, 132 consecutive pregnancies presenting for first-trimester screening, were selected at 11-14 weeks' gestation. An oblique axial view of the fetal head was routinely achieved with visualization of the posterior fossa, wherein the cisterna magna (CM) and the fourth ventricle (V4) anteroposterior diameter was measured. Moreover, 81 patients had a follow-up scan at 19-24 weeks, and the CM and transverse cerebellar diameter (TCD) were measured. Normal ranges were established at 11-14 weeks for CM and V4 according to crown-rump length (CRL). The 50th centile for CM ranges from 1.2 mm to 2.3 mm at a CRL between 45 and 85 mm. The V4 50th centile ranges from 1.8 to 2.4 mm. A positive correlation was found between the first-trimester and second-trimester CM diameter and between the first-trimester V4 and second-trimester TCD. There is an inverse correlation between the first-trimester CM and second-trimester TCD. The measurements of different components of the posterior fossa in the first trimester cannot predict the size of CM and TCD in the second trimester. The presence of the three hypoechoic structures (cerebral peduncles, V4, and CM) separated by two hyperechoic lines is easy to see and measure.

First trimester detection of fetal open spina bifida using BS/BSOB ratio

BACKGROUND

Despite the well-known second trimester ultrasound signs, current possibilities of in utero surgical repair of open spina bifida require a timely detection of the spine defect.

OBJECTIVE

To evaluate the diagnostic accuracy of the ratio between brain stem (BS) diameter and its distance to the occipital bone (BSOB) (BS/BSOB ratio) in the detection of fetuses with open spina bifida at first trimester ultrasound.

METHODS

A systematic review and meta-analysis of diagnostic accuracy was performed by searching seven electronic databases from their inception to February 2019 for all studies assessing the association between BS/BSOB ratio and diagnosis of spine bifida. Diagnostic accuracy of BS/BSOB ratio in prenatal diagnosis of spine bifida was assessed as sensitivity, specificity, positive and negative likelihood ratios (LR + and LR-), and area under the curve (AUC) on SROC curves.

RESULTS

Four studies, including 17,598 fetuses with 23 cases of open spina bifida, were included in the meta-analysis. BS/BSOB ratio showed pooled sensitivity of 0.70 (95% CI 0.47-0.87; I² = 78.3%), specificity of 1.00 (95% CI 0.99-1.0; I² = 99.2%), LR + and LR- of 51.44 (95% CI 9.53-277.64; I² = 85.5%) and 0.23 (95% CI 0.04-1.17; I² = 64.8%), respectively, and an AUC of 0.9649.

CONCLUSION

First trimester BS/BSOB ratio has a high diagnostic accuracy in detecting fetuses with open spina bifida.

Cranial sonographic markers of fetal open spina bifida at 11 to 13 weeks of gestation

OBJECTIVES

To compare the sonographic signs of spina bifida obtained on axial and sagittal views of the fetal head between 11 and 13+6 weeks of gestation.

METHODS

This was a retrospective study including 27 cases of spina bifida and 1003 randomly selected controls. Indirect markers of spina bifida were evaluated on stored ultrasound images. Intracranial translucency (IT), ratio between the brainstem and the brainstem-occipital bone distance (BS/BSOB), and maxillo-occipital (MO) line were assessed on sagittal view, whereas biparietal diameter (BPD), BPD to abdominal circumference ratio (BPD/AC), and aqueduct to occipital bone (aqueduct of Sylvius [AoS]) distance were measured on the axial plane. Reference ranges were developed, and cases of spina bifida were examined in relation to the reference range.

RESULTS

On the sagittal view, detection rates for IT below the fifth percentile, BS/BSOB above the 95th percentile, and an abnormal MO line were 52.3%, 96.3%, and 96.3%, respectively. On the axial view, detection rates for BPD, BPD/AC, and AoS below the fifth percentile were 66.7%, 70.4%, and 77.8%, respectively.

CONCLUSION

The MO line and the BS/BSOB ratio appear to be the best indirect ultrasound markers of spina bifida and can be easily obtained during the routine first-trimester scan.

Crash sign: new first-trimester sonographic marker of spina bifida

OBJECTIVES

To describe a new first-trimester sonographic sign, the 'crash sign', associated with fetal open spina bifida, and to evaluate its clinical usefulness in the first-trimester diagnosis of spina bifida.

METHODS

This was a retrospective review of patients referred to three fetal medicine centers in the first trimester (11 + 0 to 13 + 6 weeks) with suspected spina bifida. Spina bifida was confirmed by direct visualization of the spinal defect on ultrasound by two experts and, when possible, by fetal postmortem examination. Ultrasound images were reviewed for the presence of the crash sign, which is the posterior displacement of the mesencephalon and deformation against the occipital bone in the axial view. The first-trimester ultrasound images of a mixed group of 10 cases and 40 control fetuses without spina bifida were assessed for the presence of the crash sign by two assessors blinded to the diagnosis.

RESULTS

The crash sign was present in 48 out of 53 confirmed cases of spina bifida. Of these, 27 had isolated spina bifida and 21 had an associated anomaly. Of the five cases without the crash sign, one had isolated spina bifida and four had an associated anomaly. The crash sign was not reported in any of the control fetuses.

CONCLUSIONS

We have described a new first-trimester sonographic marker for the diagnosis of spina bifida. Our results suggest that the crash sign may be a useful tool in the first-trimester detection of spina bifida. Prospective evaluation of the crash sign would be beneficial, ideally in a routine clinical screening ultrasound setting. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

First trimester supratentorial and infratentorial abnormalities in fetuses with open spina bifida

OBJECTIVES

To examine whether supratentorial, infratentorial, and calvarial manifestations of open spina bifida (OSB) occur in the first-trimester.

METHODS

Supratentorial (midbrain curvature, thalamic height), infratentorial (fourth ventricle diameter, brain-stem diameter [BSD], ratio of BSD to BSD-occipital bone diameter [BSOB]), and calvarial (frontomaxillary facial [FMF] angle) parameters were measured in stored midsagittal facial images at 110-136 weeks of 500 normal and 10 open spina-bifida fetuses by 3 blinded examiners.

RESULTS

OSB fetuses displayed a larger midbrain curvature (93.26 ± 6.97 versus 97.79 ± 10.04, p < .05), decreased FMF angle (84.10 ± 5.44 versus 78.46 ± 5.82, p < .001), smaller fourth ventricle diameter (0.25 ± 0.04 mm versus 0.18 ± 0.05 mm, p < .001), smaller BSD (0.29 ± 0.04 mm versus 0.23 ± 0.04 mm; p < .001), and increased BSD to BSOB ratio (0.64 ± 0.71 versus 0.73 ± 0.93, p < .03) than normal controls, respectively. Thalamic height was not significantly altered. Detection rates of OSB were highest for fourth ventricle diameter and FMF angle (60% and 40%, respectively, at 95% specificity). BSD, BSD to BSOB ratio, midbrain curvature yielded sensitivities of 30% with 95% specificity. Two-dimensional discrimination for pairs of measures combining fourth ventricle diameter with FMF angle increased sensitivity to 90% with specificity of 90.7%.

CONCLUSIONS

Our findings suggest that supratentorial, infratentorial, and calvarial changes consistent with the Chiari-II malformation are already established in first-trimester fetuses with OSB.

First-trimester cystic posterior fossa: reference ranges, associated findings, and pregnancy outcomes

OBJECTIVE

To report reference ranges for fetal cerebral posterior fossa measurements and to describe the sonographic findings, karyotype results, and pregnancy outcomes in fetuses presenting with cystic posterior fossa (CPF) in the first trimester of pregnancy.

METHODS

Two groups of patients undergoing first-trimester sonographic screening at 11-13 weeks' gestation were studied. The first (control group) consisted of 253 consecutive fetuses with normal posterior fossa, in which the brainstem (BS), fourth ventricle, cisterna magna, and BS-occipital bone (BS-OB) diameter were prospectively measured and the BS/BS-OB diameter ratio was calculated. The second (study group) consisted of 14 fetuses in which a CPF was detected. Information on sonographic findings, prenatal karyotype results, and pregnancy outcomes was obtained by reviewing ultrasound reports and medical records. The results from the two groups were then compared.

RESULTS

In the control group, the size of all posterior fossa structures increased and the BS/BS-OB diameter ratio slightly decreased as the pregnancy progressed. In the study group, the BS diameter did not differ significantly from the measurements obtained in the control group. However, the BS-OB diameter and the fourth ventricle were significantly larger (p < .05 and p < .001, respectively) in the study group than in the control group. Additionally, the cisterna magna was not identified in 13 of the 14 fetuses (93%) in the study group, in comparison to zero out of the 253 fetuses in the control group (p < .001). Finally, the BS/BS-OB diameter ratio was significantly smaller in the study group when compared with the control group (p < .05). Regarding pregnancy outcomes, 12 of the 14 (86%) affected pregnancies underwent elective termination (n = 11) or ended in an early intrauterine demise (n = 1) due to the associated chromosomal abnormalities or structural defects. The two fetuses with isolated CPF had a normal second-trimester scan and resulted in the delivery of healthy newborn infants.

CONCLUSIONS

The detection of a CPF in the first trimester is associated with a high rate of chromosomal and structural defects. By using normative data, early sonographic screening and detection of mildly and moderately abnormal cases is possible. Fetuses with isolated CPF require further study with a detailed second-trimester scan. This is essential in order to differentiate cases with poor and good perinatal outcomes. Finally, our data also demonstrate that the main sonographic tool when screening for CPF in the first trimester is the assessment of the fourth ventricle, which is significantly larger in abnormal cases as the result of the wide communication between the fourth ventricle and the cisterna magna.

Spina bifida screening in the first trimester using ultrasound biparietal diameter measurement adjusted for crown-rump length or abdominal circumference

OBJECTIVE

Compare the performance of first trimester ultrasound biparietal diameter (BPD) screening for open spina bifida (OSB) when BPD is adjusted for crown-rump length (CRL) or abdominal circumference (AC).

METHODS

For 63 OSB and 24 265 unaffected pregnancies, BPD was expressed as multiple of the normal median (MoM) based on CRL and on AC, and as the ratio BPD/AC. Screening performance was assessed by the Mahalanobis distance, the observed detection rate with normal fifth and 10th percentile cut-offs and the area under the receiver-operator characteristic curve (AUC).

RESULTS

Mahalanobis distance for BPD MoM was considerably higher when based on AC than on CRL: 1.69 versus 1.14. Screening performance was also higher: using a fifth percentile cut-off, the detection rate was 59% compared with 41%; using a 10th percentile cut-off, the rates were 63% and 51%. Whilst the false-positives rates were slightly higher too-5.3% versus 5.1% and 10.8% versus 9.9%-the AUC was statistically significantly higher: 0.872 (95% CI, 0.816-0.928) compared with 0.735 (95% CI, 0.664-0.806). BPD/AC had intermediate performance.

CONCLUSION

The best results are obtained when AC, rather than CRL, is used to express BPD values in MoMs. First trimester OSB screening can detect half to two-thirds of cases.

Non-visualization of choroid plexus of fourth ventricle as first-trimester predictor of posterior fossa anomalies and chromosomal defects

OBJECTIVE

To assess non-visualization of the choroid plexus of the fourth ventricle (CP-4V) as a simple, qualitative and reproducible first-trimester ultrasound feature of the posterior fossa for the prediction of central nervous system (CNS) anomalies and chromosomal defects.

METHODS

First-trimester three-dimensional ultrasound datasets of the fetal brain were obtained prospectively from 65 consecutive normal singletons and retrospectively from 27 fetuses identified as having an abnormal posterior fossa on first-trimester ultrasound examination, and randomly combined to form the final study group. The stored ultrasound volumes were analyzed offline by two accredited sonologists, who were not aware of the final diagnoses. The CP-4V was assessed by multiplanar navigation and classified as visible or non-visible in its normal position depending on whether or not the echogenic structure that separates the fourth ventricle from the cisterna magna was identified in both midsagittal and axial planes. Correlation with subsequent second-trimester ultrasound, fetal magnetic resonance imaging, or postmortem or postnatal findings was performed to determine the predictive value of the first-trimester findings.

RESULTS

Among the 92 ultrasound datasets analyzed, 73 (79%) were acquired transabdominally and 19 (21%) transvaginally. The CP-4V was classified as visible in 64 cases and non-visible in 28 cases, with agreement between the two observers in both sagittal and axial planes in all but one case. Twelve of the 28 (43%) fetuses with non-visible CP-4V were subsequently diagnosed as having a CNS malformation (open spina bifida (n = 6), Dandy-Walker malformation (n = 2), Blake's pouch cyst (n = 2), cephalocele (n = 1) and megacisterna magna (n = 1)). In addition, 20 of these 28 (71%) fetuses had aneuploidy (trisomy 18 (n = 10), triploidy (n = 5), trisomy 13 (n = 3), Turner syndrome (n = 1) or trisomy 21 (n = 1)). There was only one false-positive case, in which the CP-4V was classified as absent in a normal fetus.

CONCLUSIONS

Non-visualization of the CP-4V in the first trimester appears to be a strong marker of posterior fossa anomalies and chromosomal defects. Qualitative evaluation of this anatomic structure is simple, feasible and reproducible, and its routine assessment during the first-trimester scan may facilitate the early detection of CNS anomalies and associated fetal aneuploidy. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

A prospective study on fetal posterior cranial fossa assessment for early detection of open spina bifida at 11-13 weeks

The objective of this study was to test three measurements: brain stem (BS), intracranial translucency (IT) and brain stem to occipital bone distance (BSOB), as well as one landmark: cisterna magna (CM) visibility, for early diagnosis of open spina bifida (OSB) in a low risk population. A prospective observational study was undertaken in a university hospital. A sample of 1479 women consented to participate between 20 September 2013 and 30 June 2015. Measurements were performed from the mid-sagittal view, as is routinely used for nuchal thickness assessment. CM visibility was assessed qualitatively as the third anechoic band in the posterior cranial fossa (PCF). All pregnancies were screened with a combination of maternal serum alpha-fetoprotein and second trimester anomaly scan and followed until delivery. Predictive values were calculated for each marker. We were able to diagnose two OSB cases and highly suspect one Dandy-Walker malformation case at the first trimester scan by the observation of PCF. PCF characteristics of OSB cases were increased BS diameter, increased BS-BSOB ratio and non-visualization of the CM. All the markers demonstrated high sensitivity and specificity but CM visibility reached the highest positive predictive value. Due to relatively high false positive rates, PCF measurements could not reach a satisfactory performance to validate their clinical use as a single marker. CM visibility has the advantage of being a qualitative marker and reduces the need for sophisticated and time-consuming measurements. Intracranial translucency and BS-BSOB ratio measurements should be used when the CM visibility is absent or in doubt.

Prenatal diagnosis of spina bifida: from intracranial translucency to intrauterine surgery

Accurate and timely prenatal diagnosis of spina bifida (SB) is a major goal of modern antenatal care. Prenatal screening for open SB should be first performed at the time of routine first-trimester ultrasound by examining the posterior fossa for obliteration or non-visualization of the fourth ventricle ("intracranial translucency") and cisterna magna. The second step of screening is the second-trimester anatomy scan, at which time the features of the Chiari type II malformation should be looked for, including ventriculomegaly, scalloping of the frontal bones ("lemon" sign), and backward and caudal displacement of the cerebellar vermis with obliteration of the cisterna magna ("banana" sign). In cases with positive findings, evaluation must include a focused examination of the spine for defects. In cases of closed SB and SB occulta, the cranial and posterior fossa features will not be present as they are not associated with leaking of spinal fluid and resultant hindbrain herniation, highlighting the fact that the spine should be examined thoroughly whenever possible during the second-trimester scan. In tertiary fetal medicine centers, two-dimensional and three-dimensional ultrasound allows an accurate determination of the location, type, extent, and upper level of the spinal defect as well as the presence of associated anomalies. Fetal magnetic resonance imaging should be restricted to candidates for intrauterine surgery as part of the preoperative protocol.

Rapid initiation of fetal therapy services with a system of learner-centred training under proctorship: the National University Hospital (Singapore) experience

INTRODUCTION

Management of complicated monochorionic twins and certain intrauterine structural anomalies is a pressing challenge in communities that still lack advanced fetal therapy. We describe our efforts to rapidly initiate selective feticide using radiofrequency ablation (RFA) and selective fetoscopic laser photocoagulation (SFLP) for twin-to-twin transfusion syndrome (TTTS), and present the latter as a potential model for aspiring fetal therapy units.

METHODS

Five pregnancies with fetal complications were identified for RFA. Three pregnancies with Stage II TTTS were selected for SFLP. While RFA techniques utilising ultrasonography skills were quickly mastered, SFLP required stepwise technical learning with an overseas-based proctor, who provided real-time hands-off supervision.

RESULTS

All co-twins were live-born following selective feticide; one singleton pregnancy was lost. Fetoscopy techniques were learned in a stepwise manner and procedures were performed by a novice team of surgeons under proctorship. Dichorionisation was completed in only one patient. Five of six twins were live-born near term. One pregnancy developed twin anaemia-polycythaemia sequence, while another was complicated by co-twin demise.

DISCUSSION

Proctor-supervised directed learning facilitated the rapid provision of basic fetal therapy services by our unit. While traditional apprenticeship is important for building individual expertise, this system is complementary and may benefit other small units committed to providing these services.

Intracranial translucency assessment at first trimester nuchal translucency ultrasound

INTRODUCTION

The antenatal diagnosis of open spina bifida (OSB), a neural tube defect, is predominantly made at the second trimester morphology scan by ultrasound detection of structural abnormalities resulting from the associated Chiari II malformation. Evidence has emerged suggesting that these structural abnormalities can be detected earlier, by examination of the posterior fossa as part of the first trimester nuchal translucency scan. In particular, absence of the intra-cranial translucency (IT) of the fourth ventricle has shown promise as a diagnostic marker of OSB, although the sensitivity and specificity of this finding varies widely in the literature. The aim of this study is to assess the feasibility of obtaining the image of the IT at our institution as part of the routine first trimester scan.

METHODS

This is a prospective study of 900 obstetric patients who presented to a tertiary women's imaging centre for routine first trimester nuchal translucency screening ultrasound for the year 2014. Their risk status was that of the general population (low risk) prior to presentation. A total of 158 patients were excluded, leaving a study group of 742. Sonographers obtained a mid-sagittal view of the fetal face with particular focus on optimum viewing of the IT. All images were examined by a Radiology Registrar for presence or absence of IT. Duration of each scan was documented.

RESULTS

The IT image was successfully acquired in 94.9% of scans. Maternal pre-pregnancy BMI and fetal lie were shown to have a statistically significant effect on success of acquisition of the IT image. No cases of OSB were diagnosed during the study. Scan times were not lengthened by the addition of the image.

CONCLUSION

We consider that acquisition of an image of the IT as part of the routine first trimester nuchal translucency scan is feasible, without lengthening appointment times.

Normal Intracranial Translucency Values During the First Trimester of Gestation in a Latin American Population

OBJECTIVES

The purpose of this study was to establish intracranial translucency reference values in healthy fetuses from a Latin American population.

METHODS

This work was a cross-sectional retrospective correlational study. A review of sonographic reports from women between gestational ages of 11 weeks and 13 weeks 6 days at 2 health institutes in Bogota, Colombia, whose fetuses had a crown-rump length of 45 to 84 mm was conducted between January 1, 2010, and December 31, 2012. Women with multiple fetuses or with a deceased fetus were excluded.

RESULTS

Data corresponding to 1520 obstetric sonographic examinations were included in the statistical analysis. The crown-rump length was between 45 and 84 mm, with a median of 65 mm (interquartile range, 58-73 mm). The median intracranial translucency was 1.7 mm (interquartile range, 1.4-2.2 mm). Different percentiles (1st, 5th, 10th, 25th, 50th, 75th, 90th, 95th, and 99th) were established for each crown-rump length value. A correlation between crown-rump length and intracranial translucency was found, which seemed to be linear. The intracranial translucency value was not significantly correlated with the frontomaxillary angle but was correlated with nuchal translucency, nasal bone length, and metopic suture length.

CONCLUSIONS

We present normal intracranial translucency values in the first trimester of single gestations with live fetuses in a Latin American population. These values are similar to those described in other populations. The intracranial translucency value was linearly correlated with crown-rump length in fetuses between gestational ages of 11 weeks and 13 weeks 6 days, which is consistent with previous publications, although these data cannot be interpreted independently.

Appearance of fetal posterior fossa at 11-14 weeks in fetuses with Dandy-Walker malformation or chromosomal anomalies

OBJECTIVE

To describe the sonographic appearance of fetal posterior fossa anatomy at 11-14 weeks of pregnancy and to assess the outcome of fetuses with increased intracranial translucency (IT) and/or brainstem-to-occipital bone (BSOB) diameter.

METHODS

Reference ranges for brainstem (BS), IT and cisterna magna (CM) measurements, BSOB diameter and the BS : BSOB ratio were obtained from the first-trimester ultrasound examination of 233 fetuses with normal postnatal outcome (control group). The intraobserver and interobserver variability of measurements were investigated using 73 stored ultrasound images. In addition, a study group of 17 fetuses with increased IT and/or BSOB diameter was selected to assess outcome.

RESULTS

No significant intraobserver or interobserver variability was found for any measurement in the control group. In the study group, IT was increased in all cases and BSOB diameter was above the 95(th) centile of the calculated normal range in all but two (88%) cases. In 13/17 study cases, only two of the three posterior brain spaces were recognized on ultrasound. These 13 fetuses had a larger BSOB diameter than did the four cases that showed all three posterior brain spaces, and had severe associated anomalies including Dandy-Walker malformation (DWM) and/or chromosomal anomalies.

CONCLUSIONS

Visualization of the fetal posterior fossa anatomy at 11-14 weeks' gestation is feasible. Increased fluid in the posterior brain at 11-14 weeks, particularly in the case of non-visibility of the septation that divides the future fourth ventricle from the CM, is an important risk factor for cystic posterior fossa malformations, in particular DWM, and/or chromosomal aberrations. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Sonographic detection of central nervous system defects in the first trimester of pregnancy

The fetal central nervous system can already be examined in the first trimester of pregnancy. Acrania, alobar holoprosencephaly, cephaloceles, and spina bifida can confidently be diagnosed at that stage and should actively be looked for in every fetus undergoing first-trimester ultrasound. For some other conditions, such as vermian anomalies and agenesis of the corpus callosum, markers have been identified, but the diagnosis can only be confirmed in the second trimester of gestation. For these conditions, data on sensitivity and more importantly specificity and false positives are lacking, and one should therefore be aware not to falsely reassure or scare expecting parents based on first-trimester findings. This review summarizes the current knowledge of first-trimester neurosonography in the normal and abnormal fetus and gives an overview of which diseases can be diagnosed.

Development of prenatal screening--A historical overview

The first prenatal screening test to be introduced was based on a single maternal serum marker of neural tube defects. Since then various prenatal screening concepts have been developed, the most successful being Down syndrome risk estimation using multiple serum and ultrasound markers. Today a completely new approach to aneuploidy screening is available based on maternal plasma cell-free DNA testing. This has the potential to markedly improve screening performance but routine testing is currently too expensive in a public health setting. However, it can be cost-effective when used in combination with existing multi-maker tests. Some are beginning to broaden prenatal screening to include pregnancy complications such as pre-eclampsia that can be prevented using soluble low-dose aspirin treatment started before 16 weeks of gestation. Prenatal screening for cardiac abnormalities, fragile X syndrome and recessive genetic disorders is underutilized and public health planners should considered a more widespread application of available methods.

Reference range for the fetal intracranial translucency measurement between 11 and 14 + 2 weeks of gestation in a Brazilian population

OBJECTIVE

To establish a reference range for the fetal intracranial translucency (IT) measurement between 11 and 14 + 2 weeks in a Brazilian population.

METHODS

A retrospective cross-sectional study was performed with 199 low-risk singleton pregnancies during the first trimester ultrasound exam. The IT (fourth ventricle width) measurement was performed in a mid-sagittal view of fetal profile defined by two echogenic borders - the dorsal part of the brain stem anteriorly and the choroid plexus of the fourth ventricle posteriorly. Polynomial regression was used to obtain the best fit using fetal IT measurements and crown-rump length (CRL). Percentiles 5th, 50th and 95th were determined for each gestational age.

RESULTS

The mean of fetal IT ranged from 1.6 mm at CRL 45 to 2.0 mm at CRL 84 mm. A best fit curve was a first-degree polynomial regression: IT measurement = 1.001 + 0.0124 × CRL (R(2)=0.09).

CONCLUSION

Reference range for the fetal IT measurement between 11 and 14 + 2 weeks of gestation in a Brazilian population was established.

Prospective sonographic detection of spina bifida at 11-14 weeks and systematic literature review

OBJECTIVE

To conduct a literature review to assess the effectiveness of first trimester ultrasonographic markers of spina bifida (SB) integrating data with our prospective experience.

METHODS

The analysis of the SB cases that we prospectively detected in the first trimester, between January 2012 and February 2014, and a systematic review of all the papers evaluating the effectiveness of SB ultrasonographic markers at 11-14 weeks, namely brain stem diameter (BS), fourth ventricle/intracranial translucency (IT), cisterna magna (CM), brain stem/occipital bone distance (BSOB), the ratio between BS and BSOB. Some studies assess only the effectiveness of IT, others include more parameters, and few include them all.

RESULTS

We prospectively detected four SB cases, three open (OSB) and one closed (CSB), in a low risk population undergoing first trimester screening. In the three OSB, CM (in 2/3 cases) and BSOB (3/3) distance were below the 5th percentile, BS and BS/BSOB ratio (3/3) were above the 95th percentile. In the CSB, all the measurements were within normal limits.

CONCLUSION

The literature and our data agree that most fetuses with OSB demonstrate in the first trimester positive sonographic markers in the posterior fossa, but additional prospective studies are needed to establish the best protocol for OSB screening.

Biparietal/transverse abdominal diameter ratio ≤ 1: potential marker for open spina bifida at 11-13-week scan

OBJECTIVE

In the first trimester of pregnancy, a biparietal diameter (BPD) below the 5(th) percentile is a simple marker that enables the prenatal detection of half of all cases of open spina bifida. We hypothesized that relating the BPD measurement to the transverse abdominal diameter (TAD) might be another simple and effective screening method. In this study we assessed the performance of using the BPD/TAD ratio during the first trimester of pregnancy in screening for open spina bifida.

METHODS

A total of 20,551 first-trimester ultrasound scans (11-13 weeks' gestation), performed between 2000 and 2013, were analyzed retrospectively; there were 26 cases of open spina bifida and 17,665 unaffected pregnancies with a crown-rump length of 45-84 mm and a record of both BPD and TAD measurements.

RESULTS

The mean (± SD) BPD/TAD ratio was 1.00 ± 0.06 for fetuses with spina bifida and 1.13 ± 0.06 for those without (P < 0.0001). A BPD ≤ 5(th) percentile enabled the prenatal detection of 46.2% of spina bifida cases, while a BPD/TAD ratio of ≤ 1.00 detected 69.2%. If we considered cases in which either BPD was ≤ 5(th) percentile or BPD/TAD ratio was ≤ 1, we identified 76.9% of cases. In the latter case, the false-positive rate was 5.1%, while that for using a combination of both BPD ≤ 5th percentile and BPD/TAD ratio ≤ 1 was 0.6%, with a sensitivity of 38.5%. The positive predictive value of using a combination of BPD ≤ 5th percentile and BPD/TAD ratio ≤ 1 for detecting spina bifida was 8.5%.

CONCLUSIONS

Between 11 and 13 weeks' gestation, relating BPD to TAD improves considerably the diagnostic performance of using BPD measurement alone in screening for open spina bifida. Screening using this marker is simple and applicable to a large population.

Towards Detecting Open Spina Bifida in the First Trimester: The Examination of the Posterior Brain

Introduction: Our aim was to examine the value of indirect signs of open spina bifida in the mid-sagittal view of the posterior brain at the 11-13 weeks' ultrasound examination and to summarize the current evidence for the first-trimester diagnosis of spina bifida. Methods: This was a prospective study in routine obstetric population. The presence of four almost parallel lines (four-line view) in the posterior brain was recorded. Biparietal diameter (BPD), intracranial translucency (IT) and cisterna magna (CM) were measured. The ratio of IT to CM (R ratio) was calculated. Results: 2,491 pregnancies were examined prospectively. Updated reference ranges for IT and CM were constructed. There were 3 cases with open spina bifida, and the four-line view was abnormal in 2 of them. The abnormal fetuses had smaller BPD as well as pronounced reduction in the CM and increase in the R ratio. Discussion: Examination of the posterior brain was feasible in all fetuses in the setting of the routine 11-13 weeks' ultrasound examination. Indirect signs of spina bifida are visible in the mid-sagittal view of the posterior brain, and the assessment of these structures can be a reliable tool in the early identification of this abnormality.

Fluid Area Measurements in the Posterior Fossa at 11-13 Weeks in Normal Fetuses and Fetuses with Open Spina Bifida

Objectives: To measure the area of the intracranial translucency (IT) (syn: 4th ventricle) and the future cisterna magna (CM) in normal fetuses and to compare with fetuses with open spina bifida. Patients: In the midsagittal plane of the face of 220 fetuses between 11 and 13 weeks' gestation, the areas of the IT and CM were measured and the sum, defined as the posterior fossa fluid (PFF) area was calculated. Reference ranges were constructed in relation to the crown-rump length. The study group consisted of 21 fetuses with open spina bifida and showed in all cases a single pocket of fluid in the posterior fossa. Fetuses with no fluid in the fossa were excluded. This PFF-area was measured and compared with the reference range of the IT-area and the PFF-area of normal fetuses and Z-scores were calculated. Results: In normal fetuses, a significant increase of the IT-, the CM- and the PFF-area was found as a sign of the expanding posterior fossa. The mean PFF-area increased from 8.55 to 29.72 mm2 in the observation period. Fetuses with open spina bifida had reduced fluid in the posterior fossa with values ranging between 2.39 and 5.08 mm2 and significantly lower Z-scores. Conclusions: Fetuses with open spina bifida have an abnormally small posterior fossa at 11-13 weeks' and in cases where the cerebrospinal fluid is still present, the fluid area in the midsagittal plane is reduced when compared to normal fetuses. Area fluid assessment can be an additional useful measurement in suspicious cases for open spina bifida in early gestation.

Prenatal Diagnosis and Patient Preferences in Patients with Neural Tube Defects around the Advent of Fetal Surgery in Belgium and Holland

Introduction: We review the characteristics and prenatal choices of patients recently evaluated for neural tube defects (NTD) at two tertiary units. The prenatal diagnosis of NTD allows parents to consider all prenatal options. In selected cases of spina bifida aperta this also includes fetal surgery, which we started offering after combined ‘in-house' and ‘exported' training. Material and Methods: This is a retrospective review of prospectively collected data on NTD diagnosed over the last 8 years and recent fetal surgery referrals. Results: A total of 167 patients were referred for assessment at a median of 19 weeks. Cranial lesions were diagnosed significantly earlier than spinal lesions. Of the open spinal lesions, 77% were isolated. Of these, 22% were managed expectantly and 1 (1%) had fetal surgery. There was no correlation between parental decisions on prenatal management with disease-specific severity markers. We had 14 fetal surgery referrals, all but 1 from beyond our typical referral area; 6 of the assessed patients were operated on, 4 were expectantly managed and 4 requested termination of pregnancy (TOP). These pregnancy outcomes were in the expected range. Discussion: Open spina bifida is mainly diagnosed in the second trimester and 76% of subjects request TOP, irrespective of the severity indicators. The number of local patients considering fetal surgery is low.

Prospective study of intracranial translucency and the posterior brain in normal fetuses at the 11- to 13-week scan

OBJECTIVES

To evaluate the ability of sonographers to prospectively identify intracranial translucency and posterior brain structures at 11 to 13 weeks and to evaluate measurement reproducibility of brain stem and brain stem-occipital bone diameters on stored images.

METHODS

After specific training for intracranial translucency visualization, 10 nonphysician sonographers prospectively identified intracranial translucency at the 11- to 13-week scan, noting whether intracranial translucency was present, absent, or uncertain. If absent/uncertain, they documented the reason as spina bifida or an inadequate image (with reasons for the inadequate image). Measurements of brain stem and brain stem-occipital bone diameters were performed on stored images. Fifty randomly selected cases were reviewed for intraobserver and interobserver variability.

RESULTS

In 313 singleton pregnancies, the posterior brain including intracranial translucency was evaluated; 293 (93.6%) had known pregnancy outcomes. None had open spina bifida, but 7 had chromosomal or congenital abnormalities. In the remaining 286 normal fetuses, intracranial translucency was seen in 275 (96%) and uncertain in 11 (4%), due to inadequate images (top 3 reasons were fetal position [n = 8], obesity [n = 5], and retroverted uterus [n = 4]). Fetal position and gestational age were significantly associated with intracranial translucency visualization (P < .05). Intraobserver and interobserver agreement rates were moderate for measurements of brain stem diameter (intraclass correlation coefficients, 0.59 and 0.57) and substantial for brain stem-occipital bone diameter (intraclass correlation coefficients, 0.76 and 0.61). Bland-Altman analysis revealed negligible intraobserver and interobserver differences in brain stem and brain stem-occipital bone diameter measurements.

CONCLUSIONS

Intracranial translucency can be prospectively identified by trained sonographers in 96% of normal fetuses at 11 to 13 weeks. Measurements of brain stem and brain stem-occipital bone diameters are reproducible.

Maternal Serum Screening Markers and Adverse Outcome: A New Perspective

There have been a number of studies evaluating the association of aneuploidy serum markers with adverse pregnancy outcome. More recently, the development of potential treatments for these adverse outcomes as well as the introduction of cell-free fetal DNA (cffDNA) screening for aneuploidy necessitates a re-evaluation of the benefit of serum markers in the identification of adverse outcomes. Analysis of the literature indicates that the serum markers tend to perform better in identifying pregnancies at risk for the more severe but less frequent form of individual pregnancy complications rather than the more frequent but milder forms of the condition. As a result, studies which evaluate the association of biomarkers with a broad definition of a given condition may underestimate the ability of such markers to identify pregnancies that are destined to develop the more severe form of the condition. Consideration of general population screening using cffDNA solely must be weighed against the fact that traditional screening using serum markers enables detection of severe pregnancy complications, not detectable with cffDNA, of which many may be amenable to treatment options.

A Case of Enlarged Intracranial Translucency in a Fetus with Blake's Pouch Cyst

The intracranial translucency (IT) is a recently introduced marker of open spina bifida (OSB). In this study, we describe a case of a fetus affected by Blake's pouch cyst which showed alterations of BS/BSOB ratio at the first trimester screening.

Biparietal diameter at 11-13 weeks' gestation in fetuses with open spina bifida

OBJECTIVE

To ascertain the reported association between reduced biparietal diameter (BPD) at 11-13 weeks' gestation and open spina bifida and to investigate its predictive value in a single-center study.

METHODS

This was a retrospective study of fetuses in which BPD was measured at 11-13 weeks' gestation, including 27 fetuses with isolated open spina bifida subsequently diagnosed at 16-24 weeks and 7775 unaffected controls. BPD values were converted into multiples of the expected median (MoM) after adjustment for crown-rump length and maternal characteristics. Multivariable logistic regression analysis was used to determine the maternal characteristics significantly associated with spina bifida. The performance of screening was determined by receiver-operating characteristics curve analysis. BPD values at 11-13 weeks' gestation were compared with those measured in the second trimester using Z-scores.

RESULTS

BPD values at 11-13 weeks' gestation were below the 5(th) centile in 44.4% of cases of open spina bifida. In these fetuses, the median BPD MoM value was significantly smaller than that in the control group (0.930 vs 0.998 MoM; P < 0.0001). Multivariable logistic regression analysis showed a significant contribution from maternal age (P = 0.008) and BMI (P = 0.028) to the association between BPD MoM and spina bifida. The detection rate using BPD measurements in the first trimester was 55.6% with a false-positive rate of 11.6%. In fetuses with open spina bifida, the BPD Z-scores were significantly lower at 16-24 weeks compared to those recorded at 11-13 weeks (median, -1.71 (range, -3.98 to -0.20) vs -1.30 (-3.75 to 2.61); P = 0.006).

CONCLUSION

Fetuses with open spina bifida have a smaller BPD in the first trimester. This observation may be useful in early screening. It is likely that a combination of maternal characteristics such as age and BMI, fetal BPD and maternal serum alpha-fetoprotein measured in the first trimester would provide a clinically useful screening test for open spina bifida.

Examination of Intracranial Translucency as a Marker for Early Detection of Open Spina Bifida

This article focuses on the sonographic examination technique for evaluation of intracranial translucencies during the first trimester scan. Appropriate knowledge of the sonographic landmarks is the most important factor for evaluating normal as well as abnormal brain structure, and this examination may enable detection of open spina bifida at an early stage of fetal development.

Cisterna magna width at 11-13 weeks in the detection of posterior fossa anomalies

OBJECTIVE

To construct reference ranges for cisterna magna (CM) width at 11-13 weeks' gestation in healthy fetuses and determine whether open spina bifida and posterior fossa anomalies could be diagnosed in the first trimester.

METHODS

This was a retrospective study. CM width reference ranges were constructed based on the measurements obtained from 80 healthy fetuses with normal postnatal outcome undergoing routine first-trimester ultrasound at 11-13 weeks, using the Lambda-Mu-Sigma method. CM was measured in the fetal mid-sagittal view, as routinely used for nuchal translucency assessment. In addition, first-trimester ultrasound images in 11 fetuses with open spina bifida or posterior fossa anomalies, most of which were diagnosed later in pregnancy, were retrospectively reviewed, and CM measurements were compared against reference ranges.

RESULTS

CM width was noted to increase with gestational age in normal fetuses. The anomalies in the 11 fetuses we reviewed were: open spina bifida (n = 5), megacisterna magna (n = 3), Blake's pouch cyst (n = 2) and posterior fossa arachnoid cyst (n = 1). All fetuses with open spina bifida had a CM width below the 5(th) percentile. In the two fetuses with Blake's pouch cyst and in two with megacisterna magna, CM width was above the 95(th) percentile. In one of the fetuses with a megacisterna magna and the one with an arachnoid cyst, CM width was within normal range.

CONCLUSION

We have constructed reference ranges for CM width at 11-13 weeks using the mid-sagittal view. It appears that first-trimester CM width can be used as a marker for the early detection of open spina bifida. However, our findings need to be confirmed in prospective large series.

Small biparietal diameter in fetuses with spina bifida on 11-13-week and mid-gestation ultrasound

OBJECTIVES

To assess whether, at 11-13-week and mid-trimester ultrasound examinations, the biparietal diameter (BPD) in fetuses with open spina bifida is smaller than the reference range.

METHODS

In a multicenter retrospective analysis of data from 23 fetuses with open spina bifida diagnosed at 16-24 weeks, BPD at diagnosis was compared with that measured at 11-13 weeks, before diagnosis. Z-scores were calculated for comparison of BPD deviations from the reference range within the groups at 11-13 weeks and 16-24 weeks, and between these two time intervals.

RESULTS

BPD Z-scores at 11-13 weeks and 16-24 weeks were significantly lower (P < 0.0001) in fetuses with open spina bifida when compared to the reference range, with mean values of - 1.29 and - 2.14, respectively, corresponding to the 10(th) and 1.5(th) centiles, respectively. At 11-13 weeks only six of the 23 (26%) fetuses with open spina bifida had BPD below the 5(th) centile, in comparison to 16 (69%) at mid-gestation. This was confirmed by paired t-test comparing the first-trimester with the second-trimester BPD measurements, which showed significantly slower growth of the BPD in fetuses with spina bifida.

CONCLUSION

In fetuses with open spina bifida, BPD is smaller not only in the second trimester, as previously reported, but also in the first trimester. This is most likely due to loss of cerebrospinal fluid. We suggest that a BPD value < 10(th) centile in an otherwise normally grown fetus at 11-13 weeks' gestation should be considered as a potential subtle early marker for open spina bifida.

The current management of the neurogenic bladder in children with spina bifida

The urological care of the neurogenic bladder consists of 2 components: medical management with preservation of renal function and quality-oflife issues with achieving dryness and independence of bladder and bowel management. Both components are equally important for patients to live a healthy and fulfilled life. This report explores the diagnosis of the neurogenic bladder; quality-of-life issues that caregivers and patients should expect; the importance of primary care knowledge of the neurogenic bladder and treatment; surgical options; the transition of pediatric patients to adult care; and the importance of caregiver and patient understanding of their disease, treatment options, and responsibilities.

Cerebral ventricular system in fetuses with open spina bifida at 11-13 weeks' gestation

OBJECTIVE

To determine if in fetuses with open spina bifida at 11-13 weeks' gestation there are alterations in the cerebral ventricular system.

METHODS

In this study we selected 10 cases of open spina bifida and 410 normal singleton pregnancies which subsequently resulted in the delivery of phenotypically normal neonates. In all cases transvaginal sonography was carried out at 11-13 weeks' gestation and three-dimensional (3D) brain volumes were acquired. The fetal head was systematically assessed in a series of transverse views and measurements were obtained of the area of the lateral ventricles, the diameter of the roof of the third ventricle, the diameter of the aqueduct of Sylvius and the diameter of the fourth ventricle. The measurements obtained on the normal and affected fetuses were compared.

RESULTS

In normal fetuses the area of the lateral ventricles and the diameter of the roof of the third ventricle increased, the diameter of the aqueduct of Sylvius decreased and the diameter of the fourth ventricle did not change significantly with biparietal diameter (BPD). In fetuses with open spina bifida, compared with normal fetuses, the measurements of the lateral ventricle area, the diameter of the roof of the third ventricle, the diameter of the aqueduct of Sylvius and the diameter of the fourth ventricle were significantly decreased (P < 0.01).

CONCLUSION

In fetuses with open spina bifida at 11-13 weeks' gestation the intracranial collection of cerebrospinal fluid is substantially reduced.