Value of Amniotic Fluid Index Measurement in Predicting Perinatal Outcome

Abstract

Objective : The aim of this study was to evaluate the value of amniotic fluid index (AFI) measurement to predict perinatal outcome in high risk pregnancies.

Method : High risk patients referred to the Division of Maternal Fetal Medicine at Chulalongkorn Hospital for antepartum fetal assessment had an AFI determined and were divided into two groups. Patients with the AFI s 5 cm were placed in the oligohydramnios group. The remaining patients were placed in the normal group (AFI > 5 cm). The outcome of patients with oligohydramnios compared with the normal subjects was evaluated. Perinatal outcome was considered poor when there was perinatal death, intrapartum fetal distress, a five minute Apgar score of less than 7, thick meconium stained amniotic fluid or admission to the neonatal intensive care unit.

Results : A total of 315 patients were evaluated; 47 in the oligohydramnios group and 268 in the normal group. The oligohydramnios group had a greater incidence of intrauterine growth retardation (55.3% versus 9.3%, p < 0.001), poor perinatal outcome (19.1% versus 2.6%, p < 0.02) and thick meconium stained amniotic fluid (12.7% versus 1.5%, p < 0.05). The sensitivity, specificity, positive predictive value, and negative predictive value of oligohydramnios to predict intrauterine growth retardation were 50.9%, 92.0%, 55.3% and 90.7%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of oligohydramnios to predict poor fetal outcome were 56.3%, 87.3%, 19.1%, and 97.3%, respectively.

Conclusion : The presence of oligohydramnios (AFI s 5 cm.) should serve as a warning of possible fetal compromise and as an indication of the need for further detailed fetal assessment analysis. (Thai J Obstet Gynaecol 1995;7:85-93)