Microcirculatory blood flow derangements during severe preeclampsia and HELLP syndrome

To evaluate the microcirculatory blood flow in severe preeclampsia and compare it with healthy pregnant and non-pregnant women controls, using a portable intravital-microscopy technique.

Using a side-stream dark field (SDF) device, we prospectively evaluated the sublingual microcirculatory blood flow before placental delivery in 40 women with severe preeclampsia (PE-group) complicated (n=8) or not (n=32) with HELLP syndrome, 40 healthy pregnant women (HP-group) matched by gestational and chronological age, and 20 healthy non-pregnant women (NP-group). Microvessels were classified as large or small using a cutoff value of 20μm and those with continuous flow were considered as normal while sluggish, intermittent and stopped flows were considered as abnormal. We computed the proportion of well-perfused small vessels (PPV), and total and functional capillary densities (TCD and FCD) were calculated according to the total number and quantity of well-perfused small vessels per area unit, respectively.

Total capillary densities were significantly higher in all pregnant women when compared to non-pregnant controls. The PE-group exhibited, however, significantly lower TCD compared with the HP-group. Meanwhile, significant decreases in PPV and FCD were observed in the PE-group, with deeper alterations in those with coexisting HELLP syndrome. These altered PPVs were significant although incompletely reversed after placental delivery in pregnancies complicated by HELLP syndrome, while capillary densities remained unaltered at least during very early post-delivery period.

Substantial distributive microcirculatory blood flow alterations and restricted capillary densities are observed in preeclampsia, suggesting a key role for microvascular dysfunction in the pathophysiology of this condition.