Page 20 - SONO 260 The Fetal Head and Brain

Fetal Head Measurements Biparietal Diameter
The biparietal diameter measurement (BPD) of the fetal head can be taken after the first trimester has ended, typically starting between 13 and 14 weeks.
— The BPD is obtained in the axial plane at the level of the cavum septum pellucidum, thalamus, and falx cerebri.
— This is the same level as the third ventricle, which may be seen between the two lobes of the thalamus.
— The cranial bones must be symmetric on both sides of the head and the measurement is obtained from the outer table of the proximal parietal bone to the inner table of the distal parietal bone.
¢ That is to say, the measurement is obtained from leading edge to leading edge.