Fetal femur length

Femur (diaphysis) length measurement: The transducer is optimally aligned; the long axis of the femur is aligned perpendicular to the beam with both ends of the diaphysis visualized. The calipers are placed at each end of the ossified diaphysis without including the specular reflection of the distal epiphyseal cartilage (thick arrows). To ensure the maximum length is obtained, the specular reflectors from the smooth surface of the lateral aspect of the femoral epiphyseal cartilage (thick arrows) should be visible at both ends but not included as part of the measurement of the diaphysis (line).