Resistance of uterine radial artery blood flow is positively correlated withperipheral blood NKcell fraction in patients with unexplained recurrent spontaneous abortion

Abstract

ObjectiveTo evaluate whether increased peripheral blood inflammatory immune cell can induce decrease of uterine blood flow in patients with unexplained recurrent spontaneous abortion (RSA). MethodsThis study designed prospectively 33 pregnant women between 5 to 7 gestational weeks with a history of unexplained RSA included in this study. 47 normal pregnant women between 5 to 7 gestational weeks without history of infertility and/or RSA included as a control. Peripheral blood natural killer (pbNK) (CD3 -/56 + ) fractions among peripheral blood monocyte (PBMC) were checked by flow cytometry. Uterine color-pulsed Doppler trans-vaginal ultrasound for evaluation of uterine radial artery RI was checked. Uterine radial artery resistance index (RI) compared between study and control group. After then, uterine radial artery RI was compared between high pbNK cell fraction above 12.1% among PBMC and normal pbNK cells fraction below 12.1%. Correlation between pbNK cell fraction to uterine radial artery RI was also evaluated. ResultsUterine radial artery RI in early pregnancy was significantly higher in patients with RSA than that of normal control (0.60 ± 0.14 vs. 0.54 ± 0.12, P = 0.039). Especially, the mean value of uterine radial artery RI in RSA patients with elevated pbNK cells was significantly increased than that of normal control (0.62 ± 0.13 vs. 0.54 ± 0.12, P=0.029). Otherwise, pbNK cell fractions among PBMC displayed strong positive correlation to uterine radial artery RI (Pearson's correlation coefficient P=0.001, r = 0.667). ConclusionIncreased pbNK cells can evoke decreased uterine blood flow by their pro-inflammatory action on micro vascular structure such as uterine radial artery. This can be a one causative mechanism of inducing spontaneous abortion by increased NK cells. But, larger scaled study is needed for clarify our results.