Antenatal testing among 1001 patients at high risk: the role of ultrasonographic estimate of amniotic fluid volume.
OBJECTIVE
Our goal was to compare the accuracy of the amniotic fluid index and the 2-diameter pocket technique with respect to accuracy in predicting an adverse pregnancy outcome among patients at high risk undergoing antenatal testing.


METHODS
All women with high-risk pregnancies and intact membranes who underwent antenatal testing during an 18-month period were prospectively enrolled. Ultrasonographic estimates of amniotic fluid volume were performed by means of the amniotic fluid index and the 2-diameter pocket technique. Relative risks with 95% confidence intervals and receiver operator characteristic curves were calculated for patients with an ultrasonographic estimate of oligohydramnios (amniotic fluid index of </=5 cm or 2-diameter pocket of </=15 cm2) versus normal fluid level (amniotic fluid index of >5 cm or 2-diameter pocket of >15 cm2). Outcome variables studied were intrapartum and neonatal complications.


RESULTS
Among 1001 patients the mean (+/-SD) amniotic fluid index was 10.5 +/- 5 cm and the mean (+/-SD) 2-diameter pocket was 18.7 +/- 13.6 cm2. Significantly more patients (46%) were considered to have oligohydramnios according to the 2-diameter pocket criteria than according to the amniotic fluid index (21%, P <.0001, relative risk 1.7, 95% confidence interval 1.5-1.8). No significant differences in the incidences of nonreactive nonstress test results, meconium-stained amniotic fluid, cesarean delivery for fetal distress, low Apgar scores, or infants with cord pH of <7.10 were observed between the oligohydramnios and normal amniotic fluid groups (P >.05) when assessed by relative risk with confidence interval and by receiver operator characteristic curves.


CONCLUSIONS
Current ultrasonographic measurements with the amniotic fluid index and the 2-diameter pocket technique are poor diagnostic tests to determine whether a patient is at high risk for an adverse perinatal outcome.
Magann
E F
EF
Departments of Obstetrics and Gynecology, Naval Medical Center, Medical College of Georgia, USA.
Chauhan
S P
SP
Kinsella
M J
MJ
McNamara
M F
MF
Whitworth
N S
NS
Morrison
J C
JC
D000328:Adult; D000653:Amniotic Fluid / Q000000981:diagnostic imaging* / Q000502:physiology; D001034:Apgar Score; D002585:Cesarean Section; D005260:Female; D005312:Fetal Blood; D005316:Fetal Distress; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008470:Meconium; D016104:Oligohydramnios / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011256:Pregnancy Outcome; D012372:ROC Curve; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal