Four-quadrant assessment of amniotic fluid volume: distribution's role in predicting fetal outcome

The amniotic fluid (AF) index has been shown to be a useful tool in the area of antepartum surveillance. An intrapartum AF index less than or equal to 5.0 has been shown to have predictive value with respect to increased perinatal morbidity. This study was designed to determine whether the distribution of the AF within the AF index is related to perinatal outcome.

Patients presenting for labor and delivery had an AF index determined and were divided into two groups. Patients with greater than 50% of their AF distributed in the upper quadrants were placed in the "upper-greater" group. The remaining patients were placed in the "lower-greater" group. The distribution data were compared with the following variables: meconium staining, 1- or 5-minute Apgar score of less than 7, persistent variable decelerations in the first stage of labor, late decelerations, neonatal intensive care unit admission, cesarean delivery for fetal distress, and umbilical arterial and venous pH less than 7.20.

A total of 218 patients were evaluated, 125 in the upper-greater group and 93 in the lower-greater group. The upper-greater group had a greater incidence of meconium staining (32.8 versus 9.7%; P < .0001), 1-minute Apgar score of less than 7 (12.0 versus 2.2%; P < .007), variable decelerations (53.6 versus 19.4%; P < .00001), late decelerations (16.0 versus 0%; P < .0001), cesarean delivery for fetal distress (7.2 versus 0%; P < .008), umbilical arterial pH less than 7.20 (29.6 versus 8.9%; P < .0105), and umbilical venous pH less than 7.20 (8.9 versus 0%; P < .0398). These results were maintained regardless of the overall AF index.

The distribution of the fluid within the AF index is predictive of perinatal outcome. In addition, the presence of a high negative predictive value for all of the perinatal indices studied enhances the value of this technique as a potential screening tool. Application of these results could provide additional guidelines in defining the intrapartum management and therapy of patients presenting for labor and delivery.