A comparison of 3 criteria of oligohydramnios in identifying peripartum complications: a secondary analysis.

Objective: The objective of the study was to ascertain the diagnostic accuracy of 3 criteria of oligohydramnios in identifying 4 peripartum complications.

Study Design: The 3 definitions of oligohydramnios were amniotic fluid index (AFI) 5.0 cm or less and AFI <5% for gestational age (GA) using nomograms by Moore and Cayle or Magann et al. Likelihood ratio (LR) and guidelines by the Evidence-Based Medicine Working Group were used in the secondary analysis of previously published reports. AFI obtained during antepartum and intrapartum periods were analyzed separately.

Results: The 95% confidence intervals for the prevalence of oligohydramnios using the 3 criteria are significantly different in the antepartum or intrapartum analysis. The LR was <6 for ante- and intrapartum AFI to identify cesarean delivery for nonreassuring fetal heart rate tracing, Apgar score 3 or less at 5 minutes, umbilical arterial pH <7.00, and newborns' weight 5% or less for GA.

Conclusion: The 3 criteria for determining the adequacy of amniotic fluid are not fungible, and they are not useful diagnostic tests for identifying peripartum complications because LR is <10.