The impact of amniotic fluid volume assessed intrapartum on perinatal outcome.

OBJECTIVE: Our purpose was to determine the value of routine intrapartum amniotic fluid volume assessment on perinatal outcome.

STUDY DESIGN: Patients admitted for labor and delivery who were ultimately delivered between January 1988 and June 1989 with a gestational age > or = 26 weeks and who had an intrapartum amniotic fluid index composed the study group. The amniotic fluid index was determined by the four-quadrant technique on admission to labor and delivery. Oligohydramnios was defined as an amniotic fluid index < or = 5 cm (n = 170), borderline oligohydramnios as an amniotic fluid index 5.1 to 8.0 cm (n = 261), and normal amniotic fluid volume as an amniotic fluid index 8.1 to 20 cm (n = 336). Nine patients with an amniotic fluid index > 20 cm were excluded from data analysis. The oligohydramnios and borderline oligohydramnios groups were compared with the normal group with regard to antenatal, intrapartum, and postpartum variables.

RESULTS: The groups had similar maternal age, parity, gestational age at delivery, and antenatal complications. Meconium-stained amniotic fluid occurred significantly less often in the oligohydramnios group compared with the normal group (relative risk 0.67, 95% confidence interval 0.49 to 0.92). However, variable decelerations occurred significantly more often in the oligohydramnios group compared with the normal group (relative risk 1.44, 95% confidence interval 1.12 to 1.87), and cesarean delivery for fetal distress also occurred significantly more often (relative risk 6.83, 95% confidence interval 1.55 to 30.4). There was no difference in Apgar scores or neonatal complications between groups. The efficacy of intrapartum-determined oligohydramnios predicting cesarean delivery for fetal distress gave a sensitivity of 78%, a specificity of 74%, a positive predictive value of 33%, and a negative predictive value of 95%.

CONCLUSION: The amniotic fluid index for detecting intrapartum oligohydramnios is a valuable screening test for subsequent fetal distress requiring cesarean delivery.