Structural capillary rarefaction and the onset of preeclampsia.

OBJECTIVE

To estimate if reduced capillary density (ie, capillary rarefaction) precedes the onset of preeclampsia and if it could play a role in its pathogenesis. Capillary rarefaction is a consistent finding in essential hypertension.

METHODS

In this longitudinal cohort study, we recruited 322 consecutive white women, of whom 305 women completed the study. We used intravital video microscopy to measure basal (ie, functional) and maximal (ie, structural) skin capillary densities according to a well-validated protocol and measured plasma angiogenic and antiangiogenic factors. Women were studied at five consecutive predetermined visits.

RESULTS

Preeclampsia occurred in 16 women (mean onset at 35.6±4.8 weeks of gestation), 272 women had normal pregnancies, eight had hypertension, and nine pregnancies were complicated by intrauterine growth restriction. In women with a normal pregnancy, significant reduction in maximal capillary density occurred at 27-32 weeks but had resolved by the puerperium. In contrast, in women who later developed preeclampsia, structural rarefaction was greater and occurred earlier at 20-24 weeks of gestation and persisted into the puerperium. We also found that the change in soluble Endoglin from 11-16 weeks of gestation to 27-32 weeks of gestation was significantly correlated with the change in structural capillary density.

CONCLUSION

Significant structural capillary rarefaction precedes the onset of preeclampsia and could play a role in its pathogenesis.

LEVEL OF EVIDENCE: II.