First Trimester Gestational Age
Always first Identify the bladder by aiming into pelvis from just above pubic symphysis. Then identify the uterus directly adjacent to bladder. Once fetal pole is in view, find the longest axis and place calipers to measure crown rump length which works best in earlier gestations. Later gestations benefit from additional measurements like biparietal diameter, femur length, and head/abdominal circumference.
