ABSTRACT
Ultrasound (US) assessment of the fetal musculoskeletal apparatus requires a global approach to the fetal body, considering that skeletal dysplasias and neuromuscular disorders involve several or all anatomic regions simultaneously, due to the ubiquitous distribution of bones and muscles. The only exceptions are reduction defects of the limbs, congenital or acquired (amniotic band syndrome), which are regional by definition. Therefore, unlike other systems, assessment of the fetal musculoskeletal apparatus requires a multistep total-body US approach, which should include assessment of the following:
Limbs: long bones and extremities
Spine and thorax
Fetal head: calvarium and face
Bone mineralization
Any joint contractures and joint dislocations.
Each of these five points should be addressed with separate views at different degrees of magnification, which makes the evaluation of the musculoskeletal apparatus rather time-consuming and challenging. In the following sections, the diagnostic approach to the various anomalies of bones and muscles will be dealt with by the help of different diagnostic flowcharts, based on the main abnormal US finding, with the intention of making the very difficult and challenging issue of differential US diagnosis easier.