Objective: To compare the amniotic fluid index (AFI) with the single deepest pocket technique along with the other components of the biophysical profile (BPP) in predicting an adverse pregnancy outcome.
Methods: Prospective, randomized trial of amniotic fluid assessment by AFI or single deepest pocket during a BPP. Cesarean delivery for fetal distress was the primary outcome evaluated.
Results: The AFI was used in 273 pregnancies and the single deepest pocket in 264. The AFI significantly increased the number of pregnancies labeled as oligohydramnios, 102 women (38%) compared with 46 women (17%; P <.001), odds ratio (OR) = 2.84, 95% confidence interval 1.90-4.25 in the single deepest pocket group. There was no difference in the number of women with oligohydramnios in the AFI group, 16 of 102 (16%), undergoing a cesarean delivery for fetal intolerance of labor compared with the single deepest pocket group, 6 of 46 (13%; P =.676). More women with normal fluid by the AFI method (AFI > 5), 20 of 170 (12%), underwent a cesarean delivery for fetal distress than the women with normal fluid by the single deepest pocket technique (2 cm x 1 cm pocket present) group, 12 of 218 (6%; P =.037, OR = 2.22, 95% confidence interval 1.05-4.70).
Conclusion: The AFI offers no advantage in detecting adverse outcomes compared with the single deepest pocket when performed with the BPP. The AFI may cause more interventions by labeling twice as many at-risk pregnancies as having oligohydramnios than with the single deepest pocket technique.