Guidelines for the prenatal diagnosis of fetal skeletal dysplasias

Abstract

The osteochondrodysplasias, or skeletal dysplasias are a genetically heterogeneous group of over 350 distinct disorders, and many of them can present in the prenatal period as demonstrated by ultrasound. Differentiating these disorders in the prenatal period can be challenging because they are rare and many of the ultrasound findings are not necessarily pathognomic for a specific disorder. However, differentiating known lethal disorders from nonlethal disorders, providing differential diagnoses before delivery, determining postdelivery management plans and ultimately determining accurate recurrences risks to the at-risk couples improves patient care. These guidelines provide an approach to a fetus suspected of manifesting a skeletal dysplasia.

Fig. 1

Three dimensional ultrasound images of fetuses demonstrating the abnormal facial images in thanatophoric dysplasia, achondrogenesis II and achondroplasia. A, Fetus with thanatophoric dysplasia showing severe nasal flattening and distorted facial shape because of craniosynostosis. B, Profile of fetus with thanatophoric dysplasia demonstrating severe nasal flattening and trident configuration of the hands (brachydactyly). C, Fetus with achondrogenesis II showing flattened nasal bridge but no distortion of facial shape. D, Fetus with achondroplasia showing mild flattening of the nasal bridge but not as severe as thanatophoric dysplasia.