Is amniotic fluid volume status predictive of fetal acidosis at delivery?
OBJECTIVE
To ascertain if dye-determined amniotic fluid volume just prior to delivery correlates with fetal acidosis at delivery.


METHODS
The present was a prospective observational study.


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


METHODS
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
Neither ultrasound estimates nor dye-determined amniotic fluid volumes are predictive of a low umbilical artery pH at delivery.
Magann
Everett F
EF
Department of Obstetrics and Gynecology, The University of Western Australia, Perth, Australia. pmagann@obsgyn.uwa.edu.au
Chauhan
Suneet P
SP
Martin
James N
JN
D000138:Acidosis / Q000175:diagnosis*; D000328:Adult; D000653:Amniotic Fluid; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D014469:Umbilical Arteries / Q000737:chemistry