Objective: To determine the relationship between low amniotic fluid (AF) index and fetal growth retardation (FGR), fetal distress, and cesarean delivery in patients hospitalized for hypertensive disease, and to describe changes in AF status in relation to the severity of maternal disease.
Methods: The AF index in 142 hospitalized hypertensive patients was followed per an inpatient protocol with semi-weekly testing; medical records were reviewed to obtain delivery data.
Results: Fetal growth retardation was significantly associated with an AF index of 5.0 cm or less or 7.0 cm or less (P < .001) at initial assessment, with positive predictive values of 86 and 52%, respectively. However, the sensitivity of an AF index of 5.0 cm or less or 7.0 cm or less to detect FGR was limited (21 and 46%, respectively). Fetal distress and cesarean delivery were not associated with an AF index of 5.0 cm or less or 7.0 cm or less throughout observation in this cohort. Based upon a definition of oligohydramnios as an AF index of 7.0 cm or less, the AF status worsened from an initial normal value in 39% of patients whose final diagnosis was severe preeclampsia, versus only 14% of patients who were diagnosed as having mild disease. The AF index also normalized in ten patients who were originally diagnosed with oligohydramnios and admitted for expectant management. Only one of these women was diagnosed with severe preeclampsia.
Conclusions: 1) Depending on the definition, the incidence of oligohydramnios ranges from 10-30% in hypertensive patients requiring hospitalization; 2) an AF index of 5.0 cm or less at initial evaluation predicts FGR but lacks sensitivity; 3) the AF status frequently changes with serial assessment, and these changes appear to be related to the severity of hypertensive disease; and 4) the frequency of the obstetric complications studied depends more upon the severity of hypertensive disease than on its potential effect of inducing oligohydramnios.