Changes in capillary diameters in pregnancy-induced hypertension

To compare capillary diameters, density and reactivity in high-risk pregnancies complicated by pregnancy-induced hypertension (PIH) to other high-risk pregnancies not affecting microcirculation (O).

Patients hospitalized at a tertiary referral center from January to May 2012 were enrolled in the prospective pilot study. Five microscopic fields were recorded from the nailfold for capillary diameters and functional capillary density assessment. One microscopic field was assessed before and after venous congestion to evaluate the change in capillary diameters. The results were expressed as median (interquartile range). Wilcoxon rank-sum test was used for the analysis of statistical significance (level of significance was set to p < 0.05).

In total, 31 patients were available for statistical analysis (PIH = 17;O = 14). Patients in the PIH group had significantly longer capillaries (123(91;182) vs. 72(65;107)μm, p = 0.003) and higher average capillary diameter (12(10;13) vs. 10(9;11)μm, p = 0.017). The difference in mean functional capillary density was not significant (20(17;25) vs. 19(15:21), p > 0.05), however, significantly reduced capillary recruitment (1(0;7) vs. 10(6;17), p = 0.006) was found in PIH. Preeclampsia was observed in 10 patients from the PIH group. These patients did not significantly differ from the rest of the PIH group in the abovementioned variables.

This is the first pilot study concerning change of capillary diameters after venous congestion in pregnancy. The reduced capillary recruitment and reduced capability of further dilation of capillaries after venous congestion observed in women with PIH may suggest a significantly reduced functional capacity of the microcirculation and increased load on capillary endothelium in pregnancy complicated by gestational hypertension.