The detection of non-immune hydrops through second-trimester maternal serum screening

The objective was to investigate whether non-immune hydrops in euploid pregnancies is associated with alterations in the second-trimester levels of maternal serum alpha-fetoprotein (AFP), unconjugated oestriol (uE3), and human chorionic gonadotropin (hCG). Ten singleton cases of fetal non-immune hydrops were identified. The aetiology and timing of onset of the earliest signs of non-immune hydrops, including polyhydramnios, in relation to maternal serum screening for Down syndrome were assessed. There was no clear relationship between the aetiology of non-immune hydrops and the analyte levels, as aetiologies varied widely. AFP levels were elevated overall (median = 1.78 MOM) and uE3 levels were unremarkable (median = 0.82 MOM). hCG levels were elevated (median = 3.53 MOM) when non-immune hydrops was present at the time of screening, but were unremarkable (median = 0.82 MOM) when the non-immune hydrops presented later. It is concluded that second-trimester non-immune hydrops is associated with elevated hCG levels.