Efficacy of midtrimester amniotic fluid 8-isoprostane measurement in the prediction of severe preeclampsia

Kim, So Ra; Lee, Pil Ryang; Koo, Bon Sang; Kim, Jong Soo; Chung, Ji Youn; Won, Hye Sung; Kim, Ahm

Abstract

OBJECTIVE
The objective of this study is to investigate whether the amniotic fluid 8-isoprostane levels at the time of genetic amniocentesis is a marker for severe preeclampsia.
METHODS
A case-control study was conducted to compare mid-trimester concentrations of amniotic fluid 8-isoprostane in women with normal pregnancies (n=22) and in those who subsequently developed severe preeclampsia (n=22). Amniotic fluid was also obtained by amniocentesis from another women who already developed severe preeclampsia (n=22) after 20 weeks of gestation. The 8-isoprostane levels were measured by enzyme-linked immunoassay. For statistical analysis, nonparametric tests and receiver-operating characteristic curves were used where appropriate. Statistical significance was considered when probability was <0.05.
RESULTS
The levels of midtrimester amniotic fluid 8-isoprostane were found to be significantly decreased in the women who subsequently developed severe preeclampsia in comparison with those who underwent normal pregnancies (P<0.05). The levels of 8-isoprostane in preeclamptic amniotic fluid were found to be significantly decreased with respect to that in midtrimester amniotic fluid (P<0.05). No relationship was found between the midtrimester amniotic fluid 8-isoprostane levels and preeclampsia with small-for- gestational-age. After the onset of severe preeclampsia, however, the amniotic fluid 8-isoprostane levels were significantly decreased in women with small-for-gestational-age. The midtrimester amniotic fluid 8-isoprostane level of 170 pg/ml had a sensitivity of 72.7% and a specificity of 63.6% in the prediction of severe preeclampsia.
CONCLUSION
The midtrimester amniotic fluid 8-isoprostane levels may predict the later occurrence of severe preeclampsia. This study not only presents a new information that 8-isoprostane is detected in human amniotic fluid, but also provides a convincing evidence that a subclinical process from faulty placentation in early gestation is important for the occurrence of preeclampsia. Further studies are warranted to determine which mechanism causes such decrease in amniotic fluid 8-isoprostane in preeclampsia.