RESUMO
<p><b>OBJECTIVE</b>To investigate the roles of thromboxane A(2) (TXA(2)) and prostaglandin I(2) (PGI(2)) in development of oligohydramnios.</p><p><b>METHODS</b>The concentration of TXB(2) 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 TXA(2)/PGI(2) ratio. Immunohistochemistry was performed to detect the contents of TXA(2)R in vascular endothelial cell in the placental villi.</p><p><b>RESULTS</b>Compared with the control group, the concentration of umbilical cord blood TXB(2) in oligohydramnios group was significantly increased (P<0.01), but the elevation of 6-keto-PGF(2) concentration was not statistically significant (P>0.05). The oligohydramnios group showed significantly higher positivity rates of TXB2 and 6-keto-PGF1 in than the control group (P<0.01), and the positivity rate of TXA(2)R 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%, P<0.05). Most of the TXA(2)R-positive cases in the oligohydramnios group showed strong positivities of TXA(2)R.</p><p><b>CONCLUSION</b>Abnormal elevation of TXA(2) concentration in the umbilical cord blood and the TXA(2)/PGI(2) imbalance are responsible for the development of oligohydramnios.</p>