Multiple-marker screening in pregnancies with hydropic and nonhydropic Turner syndrome

The combination of maternal serum alpha-fetoprotein, unconjugated estriol, and human chorionic gonadotropin levels and maternal age has been used to increase the sensitivity of screening for fetal Down syndrome and trisomy 18 in early-second-trimester pregnancies. We hypothesized that a unique pattern of these analytes also may be characteristic of fetal Turner syndrome, with or without hydrops.

We studied preamniocentesis, second-trimester maternal serum specimens from seven hydropic and eight nonhydropic cases of fetal Turner syndrome. Clinical and pathologic records were reviewed. Statistical analysis of the data was performed by the rank sum test.

In both hydropic and nonhydropic cases, alpha-fetoprotein levels were slightly reduced, and unconjugated estriol levels were markedly reduced. In hydropic pregnancies human chorionic gonadotropin levels were elevated, and nonhydropic pregnancies had low human chorionic gonadotropin levels (p = 0.001).

The results suggest that the morphologic defect of hydrops, rather than the aneuploidy itself, is responsible for the elevation in human chorionic gonadotropin. In conjunction with the low unconjugated estriol levels, the elevation in human chorionic gonadotropin levels will result in the prenatal identification of hydropic fetal Turner syndrome pregnancies as being at increased risk for fetal Down syndrome.