Fetal Acidemia in the Absence of Fluid Observed at Amniotomy

ABSTRACT

The objective of this study was to determine the rate of pathological fetal acidemia in the absence of fluid observed at amniotomy. Thirty-nine consecutive patients with no fluid observed at the time of amniotomy were prospectively enrolled in this study. Ultrasound measurement of amniotic fluid index was performed. Umbilical cord gases were performed on arterial and venous samples at the time of delivery. Patient name and medical record number were noted and delivery data were extracted from review of the medical record. The median gestational age at admission was 41 weeks (range 38 to 42 weeks). Sixteen patients (41%) were subsequently noted to have meconium at the time of delivery. The median amniotic fluid index was 2.0 cm with a range of 0 to 9.0 cm. Thirty patients (76.9%) had an amniotic fluid index of less than 5.0 cm. The median umbilical artery pH in this patient population was 7.21 with a range of 6.75 to 7.42. Only one infant had an umbilical artery pH less than 7.00. The rate of cesarean section for documented fetal distress was 2.6%. The absence of observed fluid at amniotomy, while commonly associated with subsequent meconium at delivery, is not predictive of fetal acidemia or operative delivery for fetal distress.

Keywords

Amniotomy - oligohydramnios - acidemia - meconium