title: Ultrasound assessment of amniotic fluid volume: a comparison of the single deepest pool and amniotic fluid index to predict perinatal morbidity.
abstract: The ability of the amniotic fluid index and the single deepest pool to predict perinatal morbidity was compared in 291 high-risk singleton pregnancies without ruptured membranes or fetal renal abnormalities. A poor outcome was defined as a birth weight < -2 standard deviations, emergency Cesarean section for fetal heart rate abnormalities in labor, 5-minute Apgar score < 7, umbilical venous pH at delivery < 7.15 and admission to the special care baby unit. At least one of these parameters occurred in 71 (24%) of the 291 pregnancies. Oligohydramnios (an amniotic fluid index <or= 5 cm) occurred in 19 (6.5%) of the 291 pregnancies; this group was more likely to have a poor outcome than those with an amniotic fluid index > 5 cm (chi(2) = 2.41, p = 0.02). There was a significant correlation between amniotic fluid index and single deepest pool measurements (r = 0.83, n = 291, p < 0.0001). At the recommended cut-off values, the single deepest pool and the amniotic fluid index had sensitivities of 7% and 13%, respectively and specificities of 96% and 95% for predicting perinatal morbidity. Receiver operating characteristic curve analysis showed that these poor results were not the result of the cut-off values chosen and that the performances of the amniotic fluid index and single deepest pool were similar.
authors.affiliation: Fetal Surveillance Unit, Department of Obstetrics and Gynaecology, King's College Hospital, UK.
authors.forename: R A
authors.initials: RA
authors.lastname: Ajayi
authors.forename: P W
authors.initials: PW
authors.lastname: Soothill