Correlation between oligohydramnios and abnormal expressions of TXA_2, PGI_2 and TXA_2R in the umbilical arterial blood and placenta

Objective To investigate the roles of thromboxane A2 (TXA2) and prostaglandin I2 (PGI2) in development of oligohydramnios. Methods The concentration of TXB2 and 6-keto-PGF1 in umbilical cord blood collected from 30 normal parturients (control) and 30 parturients with oligohydramnios was detected by radioimmunoassay to calculate the TXA2/PGI2 ratio. Immunohistochemistry was performed to detect the contents of TXA2R in vascular endothelial cell in the placental villi. Results Compared with the control group, the concentration of umbilical cord blood TXB2 in oligohydramnios group was significantly increased (P0.01), but the elevation of 6-keto-PGF1 concentration was not statistically significant (P0.05). The oligohydramnios group showed significantly higher positivity rates of TXB2 and 6-keto-PGF1 in than the control group (P0.01), and the positivity rate of TXA2R in the vascular endothelial cells in the placental villi was also significantly higher in the oligohydramnios group (22/30, 77.3% vs 11/30, 36.7%, P0.05). Most of the TXA2R-positive cases in the oligohydramnios group showed strong positivities of TXA2R. Conclusion Abnormal elevation of TXA2 concentration in the umbilical cord blood and the TXA2/PGI2 imbalance are responsible for the development of oligohydramnios.