Conflicting umbilical artery Doppler findings in fetuses with trisomy 21

To assess differences between fetuses with isolated and non-isolated trisomy 21 in umbilical artery (UA) Doppler findings in the second and third trimester and to correlate those with placental histology.

Retrospective analysis of UA pulsatility index (PI) in 281 fetuses with trisomy 21. Cases were divided into isolated trisomy 21 (group I, n = 148, 52.7 %) and non-isolated trisomy 21 (group II, n = 133, 47.3 %). UA measurements were evaluated in five different time periods (A-E; <20 + 0 to ≥ 35 + 0 weeks) and were assigned histopathology of the placenta.

In 118/281 (42 %) cases, UA measurement was abnormal. The frequency of PI values above the 95th percentile increased significantly with gestational age in both groups (period A 32.9 % vs. period E 63.6 %, p < 0.0001). There was neither a difference in abnormal UA PI values between isolated and non-isolated cases [37.8 % (56/148) vs. 46.6 % (62/133)] nor a correlation to placental findings.

Fetuses with trisomy 21 often present with elevated UA PI in the late second or third trimester, irrespective of small for gestational age growth, malformations or histopathological findings of impaired placentation.