How should femur length be measured correctly?

To measure femur length accurately, the long axis of the femur shaft should be positioned perpendicular to the imaging beam. This orientation ensures that the measurement captures the true length of the femur without distortion that could result from angling the imaging plane. When the femur is perpendicular to the beam, it minimizes magnification errors and allows for a more precise assessment of femoral size, which is critical for evaluating fetal growth and development during obstetric assessments.

Using this technique facilitates obtaining accurate biometric data, which can be vital for identifying potential growth discrepancies and influencing clinical decisions regarding the management of the pregnancy. Measurements taken with the femur in the appropriate axis are foundational for establishing gestational age based on ultrasound parameters.