USG Signs of Spina Bifida
The intracranial signs which aid in diagnosis are :
• Small BPD
• Venticulomegaly (> 10 mm)
• Frontal bone scalloping- Lemon sign – as shown in the usg given inthe question.
• Elongation and downward displacement of cerebellum - called as Banana sign
(banana sign disappears after 24 weeks)
• Obliteration of cisterna magna
Note: Ninety nine percent of fetuses with NTD have one of the above - mentioned 5 specific cranial abnormalities.
✓ Lateral ventricle is measured at the atrium -
√ Normal = 7mm from 15wks onward.
• Mild - ventriculomegaly -10-15 mm
• Overt->15 mm
• A dangling choroid plexus is seen in severe cases.