Ductus venosus Doppler velocimetry for the detection of Down syndrome: new criterion of risk

Abstract

Objective: To test the hypothesis the application of ductus venosus Doppler velocimetry may serve as a screening tool between 10 and 14 weeks gestation for the detection of fetuses with Down syndrome and estimate new criterion of risk.Patients and methods: A total of 491 fetuses were studied consecutively. In 132 cases, a cytogenetic study was performed on material obtained from a biopsy of the chorionic villus, and in 359 cases the postnatal pheno‐type was used as a basis for the result. In addition to the routine ultrasonographic examination, all the fetuses were submitted to measurement of the nuchal translucency thickness. For statistical analysis the Student's t‐test and ANOVA were used. The sensibility, specificity, positive and negative predictive values, false‐positive probability and likelihood ratio was calculated.Results: There were 21 cases of Down syndrome. Of these 21 fetuses, ductus venosus blood flow during atrial contraction was either absent (n = 3) or reversed (n = 17) in 95.2%. In the chromosomally normal fetuses (n = 270), only eight had abnormal Doppler profiles in the ductus venosus (specificity = 98.2%, positive and negative predictive values = 71.4 and 99.8%, respectively, and positive and negative likelihood ratio was 56 and 0.1, respectively).Conclusion: Our preliminary results suggest that the presence of Down syndrome may be strongly suspected when there is reverse or absent flow in the ductus venosus Doppler velocimetry during atrial contraction. We speculate the possibility of new criterion to calculate the new risk of Down syndrome was calculated from the fetal medicine foundation risk, multiplied by a likelihood rate of Doppler of ductus venosus, using at least the values of 50 for positive likelihood rate and 0.1 for negative likelihood rate.