Management of Kell isoimmunization — evaluation of a Doppler‐guided approach

Abstract

Objective To assess the role of peak systolic velocity in the middle cerebral artery (MCA‐PSV) in the management of pregnancies complicated by Kell isoimmunization. Methods Sixteen fetuses were monitored by conventional protocol (Group 1) and eight fetuses by an MCA‐PSV‐guided protocol (Group 2). The conventional protocol included a weekly ultrasound evaluation and measurement of maternal anti‐Kell titers every 4–6 weeks. In Group 2 Doppler assessment of the MCA‐PSV was performed at intervals of 4 to 7 days and MCA‐PSV > 1.5 multiples of the median (MoM) was considered as an indication for fetal blood sampling (FBS). Results No parameter emerged as a reliable predictor of isoimmunization severity in Group 1. In Group 2, no FBS was necessary in one case since the MCA‐PSV values obtained during the follow‐up were < 1.29 MoM. In two cases the first FBS was already indicated after 1 week of follow‐up, but five other fetuses were followed for 3–9 weeks before FBS was indicated. All fetuses with MCA‐PSV > 1.5 MoM prior to intrauterine transfusion (IUT) had severe fetal anemia on FBS. In fetuses with severe anemia on the first FBS, the MCA‐PSV values 7 days before the first FBS were < 1.29 MoM (four cases), between 1.29 and 1.5 MoM (two cases) and > 1.55 MoM (one case). Conclusions In the management of Kell isoimmunization invasive procedures may be avoided by implementing MCA‐PSV measurements. Delineation of appropriate intervals between reassessments, the reliability of MCA‐PSV following repeated IUTs, and cut‐off values for FBS await further study. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.