Is Doppler prediction of anemia effective in the growth-restricted fetus?

To evaluate the utility of middle cerebral artery (MCA) and umbilical artery (UA) Doppler to predict anemia in intrauterine growth restricted (IUGR) fetuses.

Fetuses with an abdominal circumference < 5th percentile had UA and MCA Doppler prior to delivery. The UA pulsatility index (PI), MCA PI, ratio between the MCA/UA PI (cerebroplacental ratio, CPR) and MCA peak systolic velocity (PSV) were measured. A complete blood count was determined from a peripheral venous sample drawn at delivery. Anemia was defined as a hemoglobin value of < 13 g/dL. MCA PSV Z-scores (standard deviation from gestational age mean using references ranges by Mari et al. and Kurmanavicius et al.) were related to hemoglobin using linear regression analysis. In addition, UA absent end-diastolic velocity (AEDV), brain sparing (MCA PI > 2 SDs below gestational age mean), low CPR (> 2 SDs below gestational age mean) and an elevated MCA PSV (> 2 SDs) were evaluated for their predictive accuracy for anemia.

Of 97 IUGR neonates 23 were anemic (23.7%). The MCA PSV was significantly related to hemoglobin using either reference range (Mari et al., F = 22.1577, Kurmanavicius et al., F = 21.8188, P < 0.001, respectively). However, using categorical cut-offs as well as regression analysis none of the Doppler parameters could be identified to provide clinically useful prediction of anemia.

Parameters of MCA and UA vascular impedance and MCA PSV are significantly related to anemia in IUGR neonates. Despite this relationship the predictive accuracy is unacceptable for the clinical application in the setting of IUGR. Altered cardiovascular dynamics in IUGR fetuses may be responsible for this effect.