During the anatomy scan, use axial scanning to assess the following:
Normal shape of the fetal head/skull and cranial bone ossification (trans-thalamic or trans-ventricular planes). Look for bone ossification in the sagittal plane; examine the frontal area to rule out frontal bossing and the occipital area to identify posterior encephalocele
Biparietal diameter and head circumference (trans-thalamic plane)
Symmetry of hemispheres (trans-thalamic or trans-ventricular planes)
Presence of a central interhemispheric fissure and a falx dividing equally the hemispheres (trans-thalamic or trans-ventricular planes)
Occipital horn of the lateral ventricle distal to the transducer (trans-ventricular plane). Evaluate both occipital horns of the lateral ventricles
Atrial width of the lateral ventricle distal to the transducer (trans-ventricular plane)
Presence and orientation of two frontal horns of the lateral ventricles medially separated by cavum septi pellucidi (CSP; trans-thalamic or trans-ventricular planes)
Presence of the CSP (trans-thalamic or trans-ventricular planes). The median/midsagittal view should be performed to directly demonstrate the corpus callosum in terms of presence/absence (complete-partial)
Presence of two thalami separated from each other in the midline (trans-thalamic plane)
Presence of a normal developed silvian fissure could be assessed for its shape at the mid-trimester anatomy scan (trans-ventricular plane as well as trans-thalamic plane)
Presence of normal cerebellar hemispheres joined in the middle by the cerebellar vermis (trans-cerebellar plane)
Transverse cerebellar diameter (trans-cerebellar plane)
Presence of a normal cisterna magna (trans-cerebellar plane)
Measurement of the cisterna magna (trans-cerebellar plane)
Assess the presence and regularity of the entire spine (including the sacrum) and integrity of the skin by a sagittal scan.
For more information, go to Ultrasound Examination of Fetal CNS Clinical Practice Guidelines (ISUOG, 2021).
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Cite this: Fetal Central Nervous System Examination Clinical Practice Guidelines (WAPM, 2021) - Medscape - Dec 06, 2021.