Ultrasound in Prenatal Diagnostics and Its Impact on the Epidemiology of Spina Bifida in a National Cohort from Denmark with a Comparison to Sweden

Objectives The aim of this study was to assess the incidence, the prenatal detection rate by ultrasound, and the pregnancy outcome of spina bifida (SB) in Denmark (DK) in 2008-2015 and to compare results to national data from Sweden. Methods Data were retrieved from the Danish Fetal Medicine Database, which includes International Classification of Diseases- (ICD-) 10 codes for pre- or postnatally diagnoses and pregnancy outcome. Missing data were obtained from the National Patient Register. Livebirth data with myelomeningocele (MMC) in Sweden were obtained from different databases. Results There were 234 cases with SB in DK in 2008-2015. The incidence of SB was 4.9 : 10,000; 89% were detected with ultrasound prior to week 22; 90% of these pregnancies were terminated (ToP); 91% were isolated malformations of which 11% showed abnormal karyotype. The incidence of newborns with MMC was 1.3 : 10,000 in Sweden. Conclusions Ultrasound screening has a major impact on the epidemiology of SB. The prenatal detection rate of SB was high, and most SB cases were isolated and had a normal karyotype. Among women with a prenatal fetal diagnosis of SB, 90% chose to have ToP. The incidence of newborns with SB was higher in Sweden than in DK.