Early detection of reversed diastolic umbilical flow: should we offer karyotyping?

In normal pregnancy, end-diastolic flow appears in the umbilical artery around the 13th week of gestation, with a velocity which increases progressively with advancing gestation. The detection of reversed flow in the umbilical artery, the highest expression of an increase in placental vascular resistance, is extremely uncommon in the first half of gestation and, in three of the four cases reported in the literature, there were chromosomal abnormalities. We report a new case of reversed end-diastolic flow in the umbilical artery in a 13-week fetus with increased nuchal translucency thickness, megacystis and tachycardia. Cytogenetic analysis of chorionic villi and amniocytes revealed trisomy 13. The findings provide further evidence for a possible association between reversed end-diastolic flow in the umbilical artery and chromosomal abnormalities. However, the effectiveness of this potential marker in an unselected population requires further evaluation.