How well do the amniotic fluid index and single deepest pocket indices (below the 3rd and 5th and above the 95th and 97th percentiles) predict oligohydramnios and hydramnios?

Objective This study was undertaken to determine whether the amniotic fluid index (AFI) and single deepest pocket percentiles can reliably identify a dye-determined amniotic fluid volume. Study design Ultrasound measurements and dye-determined volumes were prospectively collected. Oligohydramnios predictors included AFI and single deepest pocket below the 3rd and 5th percentiles, and hydramnios predictors were based on AFI and single deepest pocket above the 95th and 97th percentiles. Results Two hundred ninety-one women with singleton pregnancies participated, including 75 pregnancies (26%) with oligohydramnios and 31 pregnancies (10%) with hydramnios. The predictive ability of the AFI and single deepest pocket indices (<3rd and 5th percentiles) to identify oligohydramnios was between 11% and 27% and to identify hydramnios (>95th and 97th percentiles) ranged between 33% and 46%. The best prediction was for normal fluid volume with an accuracy of 83% to 94%. Conclusion Amniotic fluid indices perform best for the identifying normal AF volumes, whereas the identification of oligohydramnios or hydramnios is poor.