Correlation of amniotic fluid index and nonstress test in patients with preterm premature rupture of membranes

Abstract

The amniotic fluid index and the nonstress test are commonly used in the expectant management of preterm premature rupture of membranes. This study was designed to investigate the interrelationship of the nonstress test and the amniotic fluid index during the preterm rupture of membranes latency period. Fifty patients with preterm premature rupture of membranes for greater than 48 hours were prospectively followed with daily 1-hour nonstress tests and blinded, daily amniotic fluid index examinations (totaling 422 evaluations). The overall average daily amniotic fluid index was statistically lower in the earlier gestations and nulliparous patients but was not influenced by the fetal position or nonlaboring uterine activity. An increased incidence of variable decelerations and nonreactive nonstress tests was associated with a significantly lower overall average daily amniotic fluid index, but these differences were beyond the standard precision of the amniotic fluid index examination. The daily nonstress test appears to identify clinically significant lower fluid volumes during the latency period and should remain the mainstay in the management of preterm premature rupture of membranes.