Rheological parameters in the umbilical cord blood in moderate and severe forms of preeclampsia

Previous studies have dealt with maternal blood rheology in preeclampsia (PE), but only a few focused on the fetal rheological parameters in this maternal state. PE is one of the most common severe complications of pregnancy world-wide associated with high maternal morbidity and mortality and intrauterine fetal growth restriction. Our objective was to explore the rheological parameters in the umbilical cord blood at term in the presence of moderate and severe forms of PE.

A subgroup analysis was performed in a community based retrospective study of 4,951 consecutively recorded singleton pregnant women of whom 423 had PE. In the latter, umbilical cord blood was collected during delivery for testing of hematological and blood rheological parameters of their fetus. Fetal results from uneventful pregnancy were compared with those associated with preeclampsia. Furthermore, results were also evaluated in the presence of moderate and severe forms of PE. Plasma viscosity (pv) was examined using KSPV 1 Fresenius and Red Blood Cell (RBC) aggregation (stasis: E0 and low shear: E1) using MA1-Aggregometer; Myrenne.

According to the definition of the German Society of Gynecology and Obstetrics (DGGG) 314 women had moderate (74.2%), while 109 had severe forms of PE due to the presence of a blood pressure > 170/110 mmHg (n = 41; 9.7%), and/or IUGR < 5th percentile (n = 28; 6.6%), and/or HELLP-Syndrome (n = 10; 2.4%), and/or proteinuria ≥ 5 g/24 h (n = 30; 7.1%). When comparing the fetal results from pregnancies with and without preeclampsia mean hemoglobin values (p < 0.001) and hematocrit (p < 0.001) were markedly higher, while plasma viscosity (p = 0.006) and erythrocyte aggreagtion (stase: p = 0.35; low shear: p = 0.08) were lower in association with preeclampsia. Gestational age, fetal birth-weight and umbilical arterial cord blood pH in women with severe PE was statistically significant lower as compared to those with moderate disease (p < 0.001). Mean hemoglobin level and hematocrit were higher in fetus from women with severe compared to moderate PE, while plasma viscosity (1.03 ± 0.07 mPas vs. 1.05 ± 0.07; p = 0.05) and erythrocyte aggregation in stase (2.3 ± 2.47 vs. 2.41 ± 2.46; p = 0.11) as well as under low shear (7.86 ± 4.63 vs. 8.06 ± 4.60; p = 0.15) were lower. HELLP-Syndrome was associated with the lowest plasma viscosity (1.00 ± 0.07 mPas; p = 0.019) and erythrocyte aggregation (low shear: 5.1 ± 5.0; p = 0.04) in fetus.

The results of this study including a notable number of patients with PE and their newborns revealed an in part statistically significant association between variables of blood rheology and the presence, severity and type of preeclampsia with a trend towards hyperviscosity in severe forms of preeclampsia. The behaviour of blood rheological components in the neonate is remarkable since the number of red blood cells is raised while RBC aggregability and plasma viscosity is low.