Prenatal Sonographic Features of Turner Syndrome

Turner syndrome (TS) was first described by Henry Turner in 1938 and was then known to be secondary to karyotypic variation of 45, X in 1959. Most conceptuses with TS spontaneously abort, and only 1% of these embryos survive to term. Fetuses with a pure and complete monosomy X often have more complicated anomalies than those with mosaicism and structural abnormalities in one X chromosome. Ultrasound has been reported to be a reliable tool in the prenatal diagnosis of TS. This article provides an overview of the common sonographic features of fetuses with TS, including cystic hygromas, increased nuchal translucency, non-immune hydrops fetalis, cardiovascular anomalies, urinary anomalies, short femur length, and other rare structural anomalies. Despite that some sonographic markers are transient and may be resolved later in gestation, detection of these markers in early pregnancy should remind obstetric clinicians of the importance of these predictors in TS. The prognosis for cases with TS detected in fetal life is relatively poor. In addition, several diseases may have phenotypic overlap with fetal TS, including non-TS-related cystic hygromas, non-TS-related non-immune hydrops fetalis and Noonan syndrome. Therefore, prenatal recognition of these sonographic features is of great help in karyotypic confirmation, and in appropriate genetic counseling and obstetric treatment.