Accuracy of ultrasound in the prenatal diagnosis of spinal anomalies

Prenatal diagnosis, natural history, postnatal treatment and outcome of 222 cases of spina bifida: experience of a tertiary center

OBJECTIVES

To report on the prenatal ultrasonographic diagnosis of spina bifida (SB) and its natural history, treatment and long-term outcome in a large tertiary referral center.

METHODS

All cases of SB diagnosed between February 1980 and December 2015 in the Obstetric Prenatal Diagnosis Day Unit of the Obstetrics and Gynecology Department at the Catholic University of the Sacred Heart, Rome, were reviewed. All infants with an open defect were delivered by elective Cesarean section and underwent early repair of the spinal defect. A ventriculoperitoneal (VP) shunt and/or third ventriculostomy was performed when needed. Complete postnatal follow-up was carried out by our multidisciplinary team in the majority of cases. The cohort was analyzed in two groups: Group 1 included patients referred between February 1980 and December 1999; Group 2 included patients referred between January 2000 and December 2015.

RESULTS

There was a total of 222 cases of SB with a prenatal diagnosis rate of 94.6% (n = 210), with the majority of defects being meningomyeloceles (n = 142 (64.0%)), affecting the lumbosacral level (n = 110 (49.5%)) and being ≥ 2 cm in size (n = 163/195 (83.6%)). There were 174 (78.4%) live births, with more terminations in Group 2 (26.1%) than in Group 1 (10.8%; P = 0.003). Postnatal surgical repair was conducted in 157 cases (99.4% of eligible cases), with death of an infant who was operated on occurring more often in Group 1 (14.1%) than in Group 2 (4.2%; P = 0.03). VP shunt placement was required in 60.3% of infants operated on after January 2000. Long-term follow-up was available for 136 children (111 with open defects and 25 with closed defects). Infants born since 2000 with an open defect had normal ambulation or a mild defect in 50% of cases and normal or mild deficit of sphincter function in 37.8% of cases. An intelligence quotient of ≥ 70 was observed in the majority of children (81.4%; 35/43 cases). Worse motor function was associated with progressive prenatal ventriculomegaly, level of lesion and VP shunt placement.

CONCLUSIONS

We describe the prenatal diagnosis, natural history and long-term outcome of a large contemporary cohort of SB fetuses and infants. In an era of pioneering fetal surgical techniques for in-utero SB repair, it is important to acknowledge that advances in conventional neonatology and pediatric neurosurgery have allowed increased life expectancy and improved quality of life in patients with SB. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Neural Tube Defects: The Experience of the Registry of Congenital Malformations of Alsace, France, 1995-2009

Context and Objective: Considering the lack of accurate and up-to-date information available about neural tube defects (NTDs) in France, the purpose of this study was to review clinical and epidemiological data of NTDs and to evaluate the current efficiency of prenatal diagnosis in Alsace (northeastern France). Methods: A population-based retrospective study was performed from data of the Registry of Congenital Malformations of Alsace between 1995 and 2009. Data were analyzed as a whole and according to the anatomical type of the malformation (anencephaly, cephalocele and spina bifida). Statistical analyses were carried out using the Statistical Package for the Social Sciences. Results: 272 NTDs were recorded divided in 113 cases of anencephaly (42%), 35 cases of cephalocele (13%) and 124 cases of spina bifida (45%). The total prevalence at birth of 14/10,000 (95% CI 13-16) was stable throughout the reporting period. A chromosome abnormality was identified in 27 cases (12% of all karyotyped cases). NTDs were prenatally diagnosed by ultrasound in 88% of the cases. The mean age upon prenatal diagnosis slightly declined during the 15-year period, significantly for spina bifida only. The global rate of terminations of pregnancy following prenatal diagnosis was 97% (230/238). Conclusion: This work constitutes a unique population-based study providing accurate and specific up-to-date data from a unique center over a longer period (1995-2009). The most important information concerns the high and stable prevalence, which calls into question the efficiency of the primary prevention by folic acid supplementation and the efficiency of prenatal diagnosis.

The early diagnosis of neural tube defects

The sonographic diagnosis of fetal neural tube defects (NTDs) has been enhanced by the recognition of associated brain and skull anomalies. Previous reports have found these anomalies to be accurate in predicting spina bifida after 16 weeks' gestation, and an inverse correlation was suggested between the presence of these sonographic markers and gestational age. Therefore, we assumed that early second-trimester sonography would be at least as accurate as that performed after 16 weeks' gestation. To examine this hypothesis, we looked for the presence of these cranial sonographic markers suggestive of open NTDs in 8011 low-risk cases, using transvaginal sonography (TVS), between the 12th and 17th week of gestation (menstrual age). Fetal NTDs were identified in ten cases (1.25/1000). The NTDs were cervico-cranial in three, lumbo-sacral in six, and thoracal in one of the ten cases. None of the seven cases examined was dyskaryotic. Cerebellar dysmorphism, 'banana' sign, cerebellar absence, and hypoplasia were detected in all the low NTDs, usually before the detection of the spinal lesion. All the sonographically diagnosed malformations were confirmed by post-abortal examination except in one case, where the patient decided to continue the pregnancy and refused follow-up. We therefore conclude that transvaginal sonographic examination of the fetal skull before the 17th week of gestation is an accurate method for the detection of low NTDs.