Prenatal diagnosis of bone dysplasias

Abstract

Bone dysplasias are individually rare but collectively common. The prenatal diagnosis of bone dysplasias, especially perinatally lethal dysplasias, is of major interest to obstetric services. The current nosology of genetic skeletal disorders addresses over 400 disorders. However, in clinical practice, we encounter only a limited number of disorders, such as FGFR3-related dysplasias, osteogenesis imperfecta, and type II collagenopathies. The recent development of non-invasive prenatal genetic testing using cell-free fetal DNA in maternal blood samples has had a major impact on the prenatal diagnosis of genetic diseases. However, imaging examinations remain critical for the final diagnosis of bone dysplasias because molecular testing only shows genetic variants, and not their pathogenicity – most variants are clinically insignificant. Bone dysplasias are typically suspected when limb shortening is identified by screening ultrasound. Further assessment can be followed by more detailed ultrasound, magnetic resonance imaging (MRI), and CT. Based on these data, rational decision-making is feasible, even when the definitive prenatal diagnosis is not feasible. Here, we highlight key images of common bone dysplasias obtained by currently available modalities.

Prenatal ultrasound findings and prenatal diagnosis of fetal skeletal dysplasia

“…Prenatal 3D-CT and MRI examinations can effectively supply ultrasound examinations and improve the diagnosis and classification of fetal SD. [15][16][17] Supersonic waves cannot detect the internal situation of bones because it is reflected by the cortical bone, which can be supplemented by fetal MRI. MRI can delineate cartilage, spine and epimetaphyseal structures, visualize the vertebral canal and spinal cord, and assess fetal lung development to determine whether SD is lethal, and provide useful information for prognosis and delivery planning.…”