Ultrasound Animal Challenge 4 – Answer

The answer to the question "What does the 'butterfly sign' in ultrasound tell you about the fetus?" is:

B) That no holoprosencephaly is present

The butterfly sign on ultrasound shows the normal appearance of the choroid plexuses of the fetal brain (axial image plain). Its absence in the first trimester is a warning sign for holoprosencephaly, a developmental disorder where the brain fails to develop to hemispheres. This abnormality is frequently incompatible with life.

Ultrasound image of brain with what looks like a butterfly with labels.

Thomas Binder and the 123sonography team

PS: If you missed the previous Animal Challenge posts you can always visit our “zoo”:

  1. Tiger-stripe Sign
  2. Snake Sign
  3. Tail of a whale