OC079: The degree of shunting in growth restricted fetuses

Abstract

Objective: Experimental and clinical studies suggest an increased shunting of umbilical blood through the fetal ductus venosus during hypoxic insults. The aim of the present study was to assess the degree of ductus venosus shunting in severely growth restricted fetuses. Methods: Forty women with fetal growth-restriction were included in the study after informed written consent. They were examined once using GE Vingmed CFM 800 ultrasound scanner. The diameter and blood velocity was determined in two different insonations for the intra-abdominal umbilical vein and the ductus venosus. The volume flow calculation in the umbilical vein was based on the weighted mean velocity, and in the ductus venosus 0.7 of the maximum velocity tracing during the heart cycle. The umbilical artery Pulsatility Index (PI) was determined in the cord and the population divided according to normal PI, PI >97.5 percentiles or absent or reversed end-diastolic velocity (ARED). The results were compared with the normal ranges presented previously, and standard deviation score was used to assess differences. Results: Compared to the reference ranges, the growth-restricted fetuses had notable shift of ductus venosus shunting. Of the total 40 fetuses 0 had shunting 97.5 percentiles. All 6 fetuses with ARED were below 32 weeks, 4/6 had shunting >97.2 percentiles, 2/6 had >100% shunting. Conclusion: Fetuses with growth-restriction tend to have higher degree of shunting through the ductus venosus. Increased degree of placental compromise is associated with increased fraction of umbilical venous blood shunted through the ductus venosus. In extreme cases the shunting seams to include blood from the portal vein.