Amniotic fluid index and single deepest pocket: Weak indicators of abnormal amniotic volumes

Objective: To compare amniotic fluid index (AFI) with the single deepest po cket in the identification of actual abnormal amniotic fluid (AF) volumes. Methods: One hundred seventy-nine women with singleton pregnancies at the U niversity of Mississippi between March 1994 and June 1999 had ultrasound es timations of AF volume sequentially using the AFI and single deepest pocket techniques. Each woman subsequently had ultrasound-directed amniocentesis with dye-dilution and spectrophotomeiric calculation of actual AF volume. Results: Actual AF volumes were low (under 5% by volume for gestational age ) in 62 women, normal (5-95%) in 100 women, and high (more than 95%) in 17 women. An AFI up to 5 cm (sensitivity 10%, specificity 96%) and a single de epest pocket up to 2 cm (sensitivity 5%, specificity 98%) were similarly in adequate in identifying dye-determined low AF volumes. Likewise, AFI above 20 (sensitivity 29%, specificity 97%) and a single-deepest pocket above 8 c m (sensitivity 29%, specificity 94%) were poor in identifying dye-determine d abnormally high volumes. Conclusion: There was no difference between AFI and single deepest pocket t echniques for identifying truly abnormal AF volumes. Both techniques were u nreliable for identifying true AF volumes. (Obstet Gynecol 2000;96:737-40. (C) 2000 by The American College of Obstetricians and Gynecologists.).