Evaluation of the prenatal diagnosis of neural tube defects by fetal ultrasonographic examination in different centres across Europe

Abstract

Objective-Evaluation of prenatal diagnosis of neural tube defects by ultrasound examination in unselected populations across Europe. Setting-Prenatal ultrasound units in areas that report to contributing congenital malformation registers. Methods-All cases with a suspected or confirmed neural tube defect and delivered within the 30 month study period were identified from 18 Congenital Malformation Registers from 11 European countries. Data on the pregnancy, prenatal scans, outcome of pregnancy, and information on diVerent screening policies for each country were analysed. Results-670 766 deliveries occurred in the area covered by the registers during the study period. A neural tube defect was diagnosed at delivery in 542 cases. In 84% of these, the lesion was isolated (166 anencephaly, 252 spina bifida, 35 encephalocele). Of the 166 isolated cases with anencephaly, 96% were correctly identified prenatally; one was missed on scan, two were wrongly diagnosed, and four were not scanned (sensitivity 98%). 84% of the prenatal diagnoses were made before 24 weeks' gestation; 86% of isolated anencephalic pregnancies were terminated. Of the 252 cases of isolated spina bifida, 171 (68%) were correctly identified prenatally; 66% of these before 24 weeks' gestation. The diagnosis was missed on scan in 60 cases and 21 were not scanned (sensitivity 75%). The mean reduction in birth prevalence because of termination of pregnancy for spina bifida was 49% (range 6-100%). There was a wide variation between centres in prenatal detection rate (33-100%), termination of pregnancy of prenatally diagnosed cases (17-100%), and gestation both at diagnosis and termination of pregnancy. Conclusion-A high prenatal detection rate for anencephaly was reported by all registers. There is a large variation in prenatal detection and termination rates for spina bifida between centres, reflecting diVerences both in policy and culture. (J Med Screen 2000;7:169-174)

Costs and Effects of Prenatal Screening Methods for Down Syndrome and Neural Tube Defects

“…Second-trimester ultrasound was assumed to be 100% sensitive and specific for anencephaly. For spina bifida it was assumed that the specificity is 100%, but that of sensitivity is 74% [11, 12]. …”

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

“…Previous studies have been undertaken about NTDs, some of them reporting data issued from French registries of congenital malformations (including ours). Nevertheless, these data were aggregated across the different centers and did not provide detailed and specific results concerning the evolution of French prenatal diagnosis over time [8,9,10,11,12]. This study is the first one to present a large French cohort of NTDs over a longer and recent period of time (1995-2009).…”

“…NTDs are one of the few congenital anomalies relevant to primary prevention with folic acid supplementation or fortification [6,7]. Significant progress has been made over the past 20 years in fetal medicine and prenatal diagnosis and nowadays the majority of NTDs are prenatally diagnosed [8,9,10,11]. …”

The Euroscan study

“…At present, studies addressing facial clefts 8 , isolated 9 and associated 10 heart malformations, limb reduction deficiencies 11 , neural tube defects 12 and abdominal wall defects 13 The detection rate varied widely between registries, from 62% to 97% for neural tube defects 12 from 11% to 48% for congenital heart disease 9,10 , from 0% to 64% for limb reduction deficiences 11 from 0% to 75% for cleft lip palate 8 , from 0% to 100% for omphalocele and from 18% to 100% for gastroschisis 13 , and from 38% to 72% for gastrointestinal anomalies (Hausler et al, unpublished data) despite the fact that the registries participating in this study used the same methodology. Variations in detection rate may result from differences in operator skill, equipment used, or the gestation at which examinations are performed.…”