First-trimester 3D fetal neurosonography: five standardised views.

BACKGROUND: There are several international guidelines for foetal anomalies scanning at 11-14 weeks' gestation. The aim of this study is to present our first-trimester specialist neurosonography protocol with examples of pathology in order to develop a systematic approach to evaluating the first-trimester foetal brain. METHODS: Women undergoing a first-trimester foetal medicine ultrasound scan between 2010 and 2020 for multiple indications underwent neurosonography according to a set protocol. 3D transvaginal brain examination was performed in all cases (2000 pregnancies scanned). We retrospectively reviewed all imaging to develop this protocol. RESULTS: We propose that the following five axial-plane parallel views should be obtained when performing neurosonography in the first trimester, moving from cranial to caudal: 1. Lateral ventricles; 2. Third ventricle; 3. Thalamus and mesencephalon; 4. Cerebellum; 5. Fourth ventricle. Examples of these images and abnormalities that can be seen in each plane are given. CONCLUSIONS: We have presented a specialist protocol for systematically assessing the foetal brain in the first trimester and given examples of pathology which may be seen in each plane. Further work is needed to prospectively assess detection rates of major abnormalities using this protocol and assess the reproducibility and learning curve of this technique.

This article suggests a way in which specialists scanning babies at 11­14 weeks of pregnancy can check the brain in a structured way. This involves looking at the brain at five levels or planes to view the developing structures. The suggested scan protocol is similar to images produced of the brain and heart at the second trimester (20 week) scan. We hope that specialists will find it useful to check the brain in this way if there are concerns raised at the dating (12 week) scan, and that this will lead to earlier detection of brain abnormalities or differences.

What brain abnormalities can magnetic resonance imaging detect in foetal and early neonatal spina bifida: a systematic review.

PURPOSE: Open spina bifida (OSB) encompasses a wide spectrum of intracranial abnormalities. With foetal surgery as a new treatment option, robust intracranial imaging is important for comprehensive preoperative evaluation and prognostication. We aimed to determine the incidence of infratentorial and supratentorial findings detected by magnetic resonance imaging (MRI) alone and MRI compared to ultrasound. METHODS: Two systematic reviews comparing MRI to ultrasound and MRI alone were conducted on MEDLINE, EMBASE, and Cochrane databases identifying studies of foetal OSB from 2000 to 2020. Intracranial imaging findings were analysed at ≤ 26 or > 26 weeks gestation and neonates (≤ 28 days). Data was independently extracted by two reviewers and meta-analysis was performed where possible. RESULTS: Thirty-six studies reported brain abnormalities detected by MRI alone in patients who previously had an ultrasound. Callosal dysgenesis was identified in 4/29 cases (2 foetuses ≤ 26 weeks, 1 foetus under any gestation, and 1 neonate ≤ 28 days) (15.1%, CI:5.7-34.3%). Heterotopia was identified in 7/40 foetuses ≤ 26 weeks (19.8%, CI:7.7-42.2%), 9/36 foetuses > 26 weeks (25.3%, CI:13.7-41.9%), and 64/250 neonates ≤ 28 days (26.9%, CI:15.3-42.8%). Additional abnormalities included aberrant cortical folding and other Chiari II malformation findings such as lower cervicomedullary kink level, tectal beaking, and hypoplastic tentorium. Eight studies compared MRI directly to ultrasound, but due to reporting inconsistencies, it was not possible to meta-analyse. CONCLUSION: MRI is able to detect anomalies hitherto underestimated in foetal OSB which may be important for case selection. In view of increasing prenatal OSB surgery, further studies are required to assess developmental consequences of these findings.

Fetal dural sinus thrombosis: A systematic review.

INTRODUCTION: Fetal dural sinus thrombosis (DST) is a rare condition. Although numerous case reports exist, the findings appear heterogenous and providing accurate patient counselling remains challenging. METHODS: A systematic literature review was conducted in accordance with PRISMA guidance. RESULTS: Thirty-one studies including 78 patients were included in this review. No association with maternal or neonatal coagulopathy, infection or trauma was found. The average gestational age at diagnosis was 25 weeks (range 17-34 weeks). Approximately half of foetuses affected were female (48.7%); one quarter were male (25.6%) and one quarter had no sex stated (25.6%). Termination of pregnancy was chosen in 25.6% of cases (20/78). In continuing pregnancies,10.3% (6/58) experienced a perinatal death. Antenatally, the majority of lesions either decreased in size (38.5%) or completely resolved (32.7%). The neonatal or childhood outcome was normal in 88.0% of survivors (44/50). The average age at follow up was 16.4 months, ranging from birth to 6 years. CONCLUSION: This review found that 10% of DST cases experience in-utero or neonatal death. In survivors, the majority of cases reduce in size or completely resolve in pregnancy and 85% are reported to have a good outcome. However, further evidence is needed regarding long-term neurocognitive sequelae.

Incidence and patterns of abnormal corpus callosum in fetuses with isolated spina bifida aperta.

OBJECTIVE: To determine the incidence and characterise corpus callosum (CC) abnormalities in fetuses with spina bifida aperta (SBA) between 18 and 26 weeks of gestation. METHODS: This was a retrospective study on fetuses with isolated SBA and who were assessed for fetal surgery. Digitally stored ultrasound images of the brain were reviewed for the presence/absence of the CC, and the length and diameter of its constituent parts (rostrum, genu, body and splenium). We used regression analysis to determine the relationship between CC abnormalities and gestational age, head circumference, ventricle size, lesion level and lesion type. RESULTS: Nearly three-quarters of fetuses with isolated SBA had an abnormal CC (71.7%, 76/106). Partial agenesis was most common in the splenium (18.9%, 20/106) and the rostrum (13.2%, 14/106). The most common abnormal pattern was of a short CC with normal diameter throughout. Of note, 20.8% (22/106) had a hypoplastic genu and 28.3% (30/106) had a thick body part. Larger lateral ventricle size was associated with partial agenesis of the CC (odds ratio [OR]: 0.14, p < 0.001) and inversely associated with a shorter CC (OR: 2.60, p < 0.01). CONCLUSION: An abnormal CC is common in fetuses with isolated SBA who are referred for fetal surgery.

Fetal Hemivertebra at 11 to 14 Weeks' Gestation.

Hemivertebra appears as an angulation of the spine on a coronal section. We evaluated the prevalence of chromosomal defects and outcome of fetuses with hemivertebra detected in the first trimester over a 9-year period in a single tertiary referral unit. There were 10 cases; 9 had other anomalies. Seven couples opted for termination of pregnancy. One pregnancy ended in fetal demise at 16 weeks, and the 2 isolated cases continued the pregnancy with delivery at term. A karyotype analysis was performed in 8 fetuses: 5 found to be euploid and 3 having trisomy 18. Comprehensive ultrasound screening allows early prenatal detection and appropriate counseling.

Ultrasound Features and Management of Body Stalk Anomaly.

OBJECTIVES: This study describes the prenatal diagnosis of body stalk anomaly (BSA) in a large series of affected pregnancies and proposes an algorithm for the differential diagnosis of abdominal wall defects in the first trimester. METHODS: This was a retrospective study of all the cases of BSA diagnosed in our tertiary unit between 2009 and 2015. In all cases, we performed a detailed ultrasound examination with particular emphasis on the appearance of the amniotic membrane and content of the amniotic sac and the coelomic cavity. RESULTS: The study included 17 cases of BSA (15 singleton pregnancies, one dichorionic-diamniotic twin pregnancy discordant for BSA and one case of conjoined twins) at a median gestational age of 12+3 (range 11+0 to 16+6) weeks. In all cases, the liver and bowel were herniated into the coelomic cavity and the amniotic sac was intact containing the rest of the fetus with a normal amount of amniotic fluid; additionally, there was severe kyphoscoliosis and positional abnormalities of the lower limbs. The umbilical cord was absent, but umbilical vessels were seen with color Doppler running from the placenta to the fetus marginally to the eviscerated abdominal content. CONCLUSION: BSA can be easily diagnosed from 11 weeks' gestation. Examination of the amniotic membrane continuity, content of both the amniotic sac and coelomic cavity and a short umbilical cord help in differentiating this condition from other abdominal wall defects.

Dilated fourth ventricle in fetuses with trisomy 18, trisomy 13 and triploidy at 11-13 weeks' gestation.

OBJECTIVE: To determine if in fetuses with aneuploidies the diameter of the fourth cerebral ventricle at 11-13 weeks' gestation is different from euploid fetuses. METHODS: The fourth ventricle at 11-13 weeks' gestation was assessed in 62 cases of trisomy 21, 32 of trisomy 18, 10 of trisomy 13, and 12 of triploidy and compared to 410 normal euploid fetuses. Transvaginal sonography was carried out and 3D brain volumes were acquired. The fetal head was assessed in an axial plane and the diameter of the fourth ventricle was measured. Values in aneuploid and euploid fetuses were compared. RESULTS: The diameter of the fourth ventricle in trisomy 18, trisomy 13 and triploidy, but not in trisomy 21, was significantly higher than in euploid fetuses. In the euploid fetuses the median diameter of the fourth ventricle was 1.9 mm and the 95th percentile was 2.5 mm. The measurements were above the median and the 95th percentile in 25 (78.1%) and 17 (53.1%) cases of trisomy 18, in 10 (100%) and 8 (80.0%) of trisomy 13, and in 10 (83.3%) and 10 (83.3%) of triploidy. CONCLUSIONS: In trisomy 18, trisomy 13 and triploidy the diameter of the fourth ventricle at 11-13 weeks' gestation is increased.

Prediction of spontaneous preterm delivery from endocervical length at 11 to 13 weeks.

OBJECTIVE: To define the potential value of endocervical length at 11 to 13 weeks' gestation in the prediction of spontaneous early delivery. METHOD: The lengths of the endocervix and cervico-isthmic complex were measured by transvaginal ultrasound at 11 to 13 weeks in singleton pregnancies, including 1492 that subsequently delivered after 34 weeks and 16 (1.1%) who had spontaneous delivery before 34 weeks. In 1320 of the cases, the measurements were repeated at 20 to 24 weeks. RESULTS: There were significant associations in the length of the endocervix and cervico-isthmic complex between 11 to 13 and 20 to 24 weeks (r = 0.548, p < 0.0001 and r = 0.194, p < 0.0001), and the respective median lengths were 32.4 and 32.2 mm for the endocervix and 45.3 and 40.4 mm for the cervico-isthmic complex. At 11 to 13 weeks in the early delivery group, compared to unaffected pregnancies, the median endocervical length was shorter (27.5 vs 32.5 mm, p < 0.0001), but there was no significant difference in the length of the cervico-isthmic complex (41.4 vs 45.4 mm, p = 0.054). CONCLUSION: In the measurement of cervical length, the endocervix should be distinguished from the isthmus. The endocervical length at 11 to 13 weeks is shorter in pregnancies resulting in spontaneous delivery before 34 weeks than in those delivering after 34 weeks.

Is neonatal risk from vasa previa preventable? The 20-year experience from a single medical center.

BACKGROUND: Vasa previa is a rare condition associated with neonatal morbidity and mortality that may be diagnosed prenatally using transvaginal sonography. The aim of this study was to assess the prenatal detection of vasa previa and its subsequent impact on neonatal outcomes in two 10-year periods (1988-1997 versus 1998-2007). METHOD: Retrospective review of all cases of vasa previa. Data on obstetrical history, modes of conception, sonographic scans, delivery mode, and neonatal outcome were retrieved and recorded. RESULT: There were 19 pregnancies (21 neonates) with confirmed vasa previa (overall incidence of 1.7/10,000 deliveries). Vasa previa were diagnosed prenatally in 10 (52.6%) cases. In cases without prenatal diagnosis, there was a higher proportion of neonates with 1' Apgar score < or = 5 and cord blood pH <7 compared with cases diagnosed prenatally (66.7% versus 10%, p < or = 0.05, and 33.3% versus 0%, p < 0.05, respectively). The prenatal detection rate of vasa previa increased from 25 to 60% between the 2 time periods (p > 0.05), whereas perinatal mortality and 1' Apgar scores < or = 5 decreased from 25 to 0% and from 50 to 33.3% (p > 0.05). CONCLUSION: Prenatal sonographic screening using targeted scans for vasa previa in women at risk or as part of routine mid-gestation scanning may significantly impact its obstetric manifestations.

Fetal surgery for open spina bifida.

KEY CONTENT: Spina bifida is a congenital neurological condition with lifelong physical and mental effects.Open fetal repair of the spinal lesion has been shown to improve hindbrain herniation, ventriculoperitoneal shunting, independent mobility and bladder outcomes for the child and, despite an increased risk of prematurity, does not seem to increase the risk of neurodevelopmental impairment.Open fetal surgery is associated with maternal morbidity.Surgery at our institution is offered and performed according to internationally agreed criteria and protocols.Further evidence regarding long-term outcomes, fetoscopic repair and alternative techniques is awaited. LEARNING OBJECTIVES: To understand the clinical effects, potential prevention and prenatal diagnosis of spina bifida.To understand the rationale and evidence supporting the benefits and risks of fetal repair of open spina bifida.To understand the criteria defining those who are likely to benefit from fetal surgery. ETHICAL ISSUES: The concept of the fetus as a patient, and issues surrounding fetal death or the need for resuscitation during fetal surgery.The associated maternal morbidity in a procedure performed solely for the benefit of the fetus/child.The financial implications of new surgical treatments.