The Effect of Inhibin A on Prenatal Screening Results for Down Syndrome in the High Risk Czech Pregnant Women.

Background: Currently, prenatal testing is based on an ultrasound examination, the testing of certain biochemical markers and, most recently, also on the analysis of fragments from the extracellular DNA of the fetus in the mother´s blood. The aim of this work was to verify whether inhibin A testing during pregnancy can help influence the risk distribution of Down syndrome screening results in high risk population and thus possibly reduce the number of unnecessarily invasive procedures, or for better stratification of risks when deciding on non-invasive DNA testing.

Methods: The concentrations of inhibin A were measured using a chemiluminescent immunoassay in two groups of screening tests. The first group (triple test) included a total of 277 pregnant women; the second group (integrated test) included 91 pregnant women. Risk assessments of screenings were performed using Alpha software, LMS.

Results: The resulting risk for pregnant women without the determination of inhibin A was higher or equal to 1:300 (triple test) and 1:150 (integrated test). Inhibin A was then measured in the monitored groups and the risk was recalculated. In the first group (triple test) the risk was lower than 1:300 in 152 pregnant women and in the other group (the integrated test) in 47 pregnant women. At the end of the study, all results were compared with the outcome of the pregnancy.

Conclusions: The results obtained show that the inclusion of inhibin A in screening protocols reduces the number of positive results in high risk population screened without inhibin A.