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Updated: Mar 27, 2026
State of the Art Cranial Ultrasound Imaging in Neonates
Published on: February 2, 2015
Sonographic detection of central nervous system defects in the first trimester of pregnancy
A C Engels1,2, L Joyeux1, C Brantner2
1Department of Development and Regeneration, Faculty of Medicine, KU Leuven, Leuven, Belgium.
Insights
First-trimester ultrasound can diagnose major fetal central nervous system abnormalities like acrania and spina bifida. However, diagnosing other conditions requires second-trimester confirmation due to limited data on first-trimester accuracy.
Area of Science:
- Medical Imaging
- Fetal Medicine
- Neurology
Background:
- Early detection of fetal central nervous system (CNS) abnormalities is crucial for timely intervention.
- First-trimester ultrasound offers a window for examining fetal development.
Purpose of the Study:
- To review current knowledge on first-trimester neurosonography in normal and abnormal fetuses.
- To outline diagnosable fetal CNS diseases in the first trimester.
Main Methods:
- Literature review of first-trimester neurosonography studies.
- Analysis of diagnostic capabilities for various fetal CNS malformations.
Main Results:
- Certain severe CNS anomalies (acrania, holoprosencephaly, cephaloceles, spina bifida) can be reliably diagnosed in the first trimester.
- Diagnosis of other conditions (e.g., vermian anomalies, agenesis of the corpus callosum) requires second-trimester confirmation.
- Limited data exists on the sensitivity, specificity, and false-positive rates for some first-trimester findings.
Conclusions:
- First-trimester neurosonography is effective for diagnosing specific severe fetal CNS abnormalities.
- Caution is advised when interpreting findings for conditions requiring second-trimester confirmation to avoid misinforming parents.
- Further research is needed to establish definitive diagnostic criteria and accuracy for all detectable first-trimester CNS anomalies.
Abstract:
The fetal central nervous system can already be examined in the first trimester of pregnancy. Acrania, alobar holoprosencephaly, cephaloceles, and spina bifida can confidently be diagnosed at that stage and should actively be looked for in every fetus undergoing first-trimester ultrasound. For some other conditions, such as vermian anomalies and agenesis of the corpus callosum, markers have been identified, but the diagnosis can only be confirmed in the second trimester of gestation. For these conditions, data on sensitivity and more importantly specificity and false positives are lacking, and one should therefore be aware not to falsely reassure or scare expecting parents based on first-trimester findings. This review summarizes the current knowledge of first-trimester neurosonography in the normal and abnormal fetus and gives an overview of which diseases can be diagnosed.
