| Objective: To investigate the normal value of amniotic fluid(AF) lactate of term fetus at labor and the correlations among AF lactate, fetal plasma lactate and maternal plasma lactate. We also try to find out the predictive value of AF lactate for fetal depression.Method : A total of 148 normal nulliparous with term singleton fetus who tried to delivered vaginally in our hospital from August, 2003 to August, 2004 were enrolled in this Study. Among them, 96 cases (observation group) had abnormal fetal heart rate(FHR) monitoring patterns in active phase or meconium-stained AF. We selected other 52 cases with healthy newborns whose FHR monitoring was totally normal during the process as control group. We measured all AF lactate levels in active phase and neonatal umbilical artery lactate levels, umbilical cord blood gas analysis at delivery respectively by dry chemical method. All neonatal blood gas was simultaneously measured at time of birth. All cases had continuously FHR monitoring during the labor.Results:(1)The distribution of concentrations of AF lactate in the control group is like normal. and we set a range of normal value for AF lactate as 5.5~8.8mmol/L.(2) The AF lactate concentrations in control group were 7.18±0.84mmol/L during the active phase and 7.49±1.12mmol/L at the time of birth with an interval of 148±40min. These numbers are of no statistical difference. (3)At time of birth the lactate concentrations of maternal plasma, fetal plasma and AF in control group were 1.52 ± 0.38mmol/L, 2.92±0.68mmol/L and 7.49± 1.12mmol/L respectively. And a positive linear correlation between the lactate concentration of umbilical artery and AF were confirmed (p<0.01). (4) In observation group, AF lactate concentration in the active phase of those who developed fetal distress and neonatal asphyxia were 10.41 ± 2.06mmol/Landl5.60±1.04mmol/L ,which is remarkablely higher than that of the control group (P<0.01) . (5) The AF lactate concentration of cases with abnormal baseline FHR and severe variable decelerations were significantly higher than the control group's. Although the AF lactate levels with mild variable decelerations and tachycardia were of no significant differences with the control group's(P>0.05), thosewith higher AF lactate concentrations are more likely to develop fetal distress(P<0.01). (6)There were no significant differences among the AF lactate levels in cases with mild meconium-stained, moderate meconium-stained AF and those of the control group (P>0.05).(7) We also tried to find out the predictive value of the AF lactate concentration in fetal distress estimation. Its sensitivity, specificity, positive predictive value and negative predictive value were 66.7%, 86.4%, 69.0%, 85.1% respectively. Conclusions: The concentration of AF lactate during normal process of delivery does not alter too much and has a normal distribution. And the level of AF lactate can well reflect the concentration of umbilical lactate which is closely related with fetal distress and neonatal asphyxia. It was elevated with severity of hypoxia. AF lactate levels can be served as an efficient, simple and noninvasive marker to predict fetal distress... |
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