Early transvaginal measurement of transcerebellar diameter in Down syndrome

Objective: To evaluate the screening utility of early transvaginal measurem ent of the transverse cerebellar diameter for identification of Down syndro me fetuses. Method: Measurements of the transverse cerebellar diameter were obtained by transvaginal sonography between 11 and 16 weeks of gestation i n 544 fetuses with a normal karyotype and in 37 Down syndrome fetuses. Resu lts: The transverse cerebellar diameter was found to show a fairly constant increment of values throughout the period evaluated with a linear relation ship to the gestational age. The measurements obtained in Down syndrome fet uses are within the normal range for gestational age. Conclusion: The trans verse cerebellar diameter cannot be considered a useful tool in the detecti on of Down syndrome in early pregnancy.