Is amniotic fluid volume status predictive of fetal acidosis at delivery?

To ascertain if dye-determined amniotic fluid volume just prior to delivery correlates with fetal acidosis at delivery.

The present was a prospective observational study.

The study took place at the University of Mississippi Medical Center, Jackson MS, USA.

The population included 100 unlaboured women undergoing an amniocentesis for the assessment of fetal lung maturity before an elective Caesarean delivery between January 1997 and December 2000.

The amniotic fluid volume was estimated by ultrasound measurement and quantified by dye-determined methodology immediately prior to Caesarean delivery. Umbilical cord artery pH was collected at the time of Caesarean delivery.

The predictive accuracy of an amniotic fluid index < or = versus > 5 to identify an umbilical artery pH of < 7.20 had a sensitivity of 0%, a specificity of 84%, and a likelihood ratio of zero. None of the dye-determined low amniotic fluid volumes were identified using the single deepest pocket technique. Dye-determined low, normal, and high amniotic fluid volume groups contained a similar number of fetuses with umbilical cord arterial pH < 7.20 (P = 0.371), < 7.10 (P = 0.460), and < 7.00 (P = 0.614). Receiver-operating characteristic curves could not identify any amniotic fluid index from 0 to 18, single deepest pocket from 0 to 12, or dye-determined amniotic fluid volume 100-1900 mL to differentiate between the two newborns with an umbilical cord artery pH < 7 from 98 babies with cord pH > or = 7.0.

Neither ultrasound estimates nor dye-determined amniotic fluid volumes are predictive of a low umbilical artery pH at delivery.