The "Lemon" and "Banana" Signs of Spina Bifida on Fetal usg.

The leakage of spinal fluid in spina bifida causes hindbrain herniation (Chiari malformation), pulling the cerebellum downward into a curved "banana" shape and causing the frontal bones to collapse inward, creating a "lemon-shaped" skull.

Clinical Bottom Line: If you observe a banana-shaped cerebellum or lemon-shaped skull, immediately conduct a meticulous targeted ultrasound of the fetal spine and refer for a fetal MRI.