The Significance of Amniotic Fluid Index at Admission as a Predictor of Latency Period in the Patients with Preterm Premature Rupture of the Membranes

Yang, Soon Ha; Park, Seon Hye; Oh, Sung Hee; Whang, Jong Dae; Roh, Cheong Rae

Abstract

OBJECTIVES
The purpose of this study was to determine the clinical significance of residual amniotic fluid volume, as measured by the amniotic fluid index(AFI), on the prediction of latency period and perinatal outcomes in patients with preterm premature rupture of the membranes(PPROM).
METHODS
Study population consisted of 103 singleton pregnancies with PPROM between 24 and 34 weeks' gestation. Amniotic fluid index was determined using transabdominal ultrasound at admission. Latency period was defined as time interval in hours between admission and delivery. All medical records of mothers and neonates were reviewed. Spearman's rho rank correlation, receiver-operator characteristic(ROC) curve analysis, survival analysis and Cox's proportional hazard model were used for statistical analysis.
RESULTS
There was a statistically significant correlation between latency period and AFI at admission. ROC curve analysis showed that AFI at admission had a significant predictive value in the prediction of latency period < 48 hours. Survival analysis demonstrated that AFI < 5.0 was strongly associated with the likelihood of shorter latency period, Cox's proportional hazard model indicated that AFI < 5.0 was a significant independent predictor for the occurrence of latency period < 48 hours even after adjustment of other independent variables. The patients with AFI <5.0 had a higher rate of cesarean section due to fetal distress than those with AFI > 5.0 but the incidence of chorioamnionitis was not significantly different between two groups. Comparing the perinatal mortality and neonatal morbidity including infectious morbidity between the neonates born to mothers with AFI <5.0 and those with AFI > 5.0, there was no significance after adjustment of gestational age at birth.
CONCLUSION
AFI at admission has a significant correlation with latency period and predictive value in prediction of latency period in the patients with PPROM. AFI <5.0 is a independent predictor for the shorter latency period.