hi my name is Shelly and today we're going to talk about fetal biometry measurements of the head in the second trimester so I've entered my patients due date according to her dating ultrasound and today she should be 20 weeks and 3 days now I'm using the C3 scanner in the obstetrical preset this is going to give me access to do the head measurements so we'll locate the baby's head what I want is a cross-sectional slice through the baby's head just above the level of the ear and it's important that we see the thalami in this and then we want to see the midline in the midline so we don't want to be kind of rotated I'm going to freeze my image go into the tools menu and we can select the BPD and I'm going to place my calipers and make adjustments from the outer skull to the inner skull and that's giving us a measurement of 4 and 1/2 CM which corresponds to 19 weeks and 5 days on this view I can also do a head circumference and so I'm going to place the scanners anteriorly and at the oxop it and then we can adjust the ellipse until it's surrounding the skull and again this is corresponding to 19 weeks and 4 days we can take a picture and those measurements will be saved in the report package now once we've established the head circumference the abdominal circumference and the femur length which I'll show you shortly the system will calculate an estimated fetal weight and a gestational age
