INTRAPARTUM OLIGOHYDRAMNIOS DOES NOT PREDICT ADVERSE PERIPARTUM OUTCOME AMONG HIGH-RISK PARTURIENTS

OBJECTIVE: Oligohydramnios can be defined by an amniotic fluid index < 5th percentile for gestational age or an amniotic fluid index less tha n or equal to 5.0 cm regardless of gestational age. The purpose of thi s prospective study was to determine whether oligohydramnios by either definition predicts accurately, in a high-risk population, the risks for cesarean section for fetal distress, Apgar score <7 at 5 minutes, and neonatal acidosis. STUDY DESIGN: An amniotic fluid index was obtai ned in 490 consecutive parturients with medical or obstetric complicat ions and a reliable gestational age. After each delivery, an umbilical arterial blood gas analysis was obtained. Both measures of amniotic f luid index were rated as screening tests with use of sensitivity, spec ificity, predictive values, and receiver-operator characteristic curve s. RESULTS: The incidences of cesarean section for fetal distress and umbilical arterial pH <7.00 were 14% and 1.8%, respectively. The 70 ne onates delivered by cesarean section for distress, compared with the 4 20 without, had a significantly higher incidence of pH <7.00 (8.5% vs 0.7%, p = 0.0004, relative risk 5.0, 95% confidence interval 2.9 to 8. 4). Sensitivity and positive predictive values of an amniotic fluid in dex <5th percentile for gestational age to predict pH <7.00 were 0.8% and 22%, respectively, and for an amniotic fluid index less than or eq ual to 5.0 cm, 0.5% and 11%, respectively. Receiver-operator character istic curves indicate that an amniotic fluid index between 0 and 20 cm cannot predict accurately which parturients will have cesarean sectio ns for distress or be delivered of a newborn with a low Apgar score at 5 minutes or a pH <7.10. CONCLUSION: Both criteria for oligohydramnio s are poor predictors of adverse outcome for high-risk intrapartum pat ients.