Diagnostic accuracy of prenatal ultrasound in identifying the level of the lesion in fetuses with open spina bifida: A systematic review and meta-analysis

Introduction: The role of prenatal ultrasound in correctly identifying the level of the lesion in fetuses with open spina bifida has yet to be determined. The primary aim of this systematic review was to report the diagnostic accuracy of ultrasound in determining the level of the lesion in fetuses with open spina bifida. The secondary aim was to elucidate whether prenatal magnetic resonance imaging (MRI) improves the diagnostic performance of prenatal imaging in correctly identifying the level of the lesion. Material and methods: Inclusion criteria were studies reporting the agreement between ultrasound, MRI and postnatal or postmortem assessment of fetuses with spina bifida. Agreement was defined as: complete (when the upper level of the lesion detected prenatally was the same recorded at postnatal or postmortem evaluation), within one (when the upper level of the lesion recorded prenatally was within one vertebral body higher or lower than that reported postnatally) and within two vertebral bodies (when the upper level of the lesion recorded prenatally was within two vertebral bodies higher or lower than that reported postnatally or postmortem evaluation). Meta-analyses of proportions were used to combine data. Results: Fourteen studies (655 fetuses) were included. Ultrasound was able to identify the correct level of the lesion in 40.9% (95% confidence interval [CI] 26.9-55.6) of cases. The upper level of the lesion recorded on ultrasound was within one vertebral body in 76.2% (95% CI 65.0-85.9) of cases and within two segments in 92.4% (95% CI 84.3-97.7). Fetal MRI detected the exact level of the lesion in 42.5% (95% CI 35.9-45.2) of cases; the level of the lesion recorded on MRI was higher in 26.4% (95% CI 20.0-33.3) of cases and lower in 32.4% (95% CI 25.5-39.7) than that confirmed postnatally. The upper level of the lesion recorded on MRI was within one vertebral body in 76.2% (95% CI 65.9-85.2) of cases and within two segments in 94.2% (95% CI 90.2-97.2). Conclusions: Both ultrasound and MRI have a moderate diagnostic accuracy in identify the upper level of the lesion in fetuses with open spina bifida.