Accuracy of prenatal diagnosis and prediction of lethality for fetal skeletal dysplasias.

OBJECTIVES: We reviewed all cases with fetal skeletal dysplasia and correlated the accuracy of prenatal diagnoses with the final post-mortem, radiological, or molecular diagnoses. The accuracy of prenatal prediction of lethality was also reviewed. METHODS: All cases of fetal skeletal dysplasia referred between October 2002 and August 2010 were reviewed. Perinatal outcome, the accuracy of prenatal diagnosis, and prediction of lethality were ascertained. Lethality was suspected when significant thoracic narrowing, severe micromelia, multiple fractures, or long bone bowing was present. RESULTS: There were 40 cases of skeletal dysplasia. Thirty-nine (97.5%) were singletons and one (2.5%) was a dichorionic twin pregnancy. Twenty-eight (70%) pregnancies were terminated, five (12.5%) were stillborn, and only seven (17.5%) cases were live born. A final diagnosis was established in 28 (70%) cases. In 29 cases with a presumptive prenatal diagnosis, this was confirmed in 23 (79.3%) cases postnatally. Lethality was predicted with 100% certainty. CONCLUSION: We report higher prenatal/postnatal concordance rates in this series. A precise prenatal diagnosis is frequently difficult and often inaccurate. Prediction of lethality is much easier and often possible with accuracy. Parents need to be aware that the outcome of many skeletal dysplasias is poor.