Values of amniotic fluid index in cases of preterm premature rupture of membranes

Aims: To measure the amniotic fluid index (AFI) in cases of preterm premature rupture of membranes (PPROM). Methods: A retrospective study of pregnancies complicated with PPROM was performed. Data collected included maternal age, parity, gestational age at PPROM and at birth, and AFI on admission. Gestational age matched AFIs were obtained from a low-risk control group in a 3: 1 ratio. Results: One hundred and two singleton pregnancies with PPROM formed the study population. The mean gestational age at PPROM was 29 +/- 5.3 weeks (range: 14-36.6 weeks). The mean AFI in the PPROM and the control groups was 5.8 +/- 3.6 cm (0-18.5 cm) and 13.7 +/- 3.2 cm (7.3-24.4 cm), respectively (P<0.001). The area under the ROC curve of AFI in the prediction of PPROM was 0.95 (P<0.001). An AFI of <= 10 cm had sensitivity, specificity, positive and negative predictive values of 89.2%, 88.5%, 72.2% and 96%, respectively, in supporting the diagnosis of PPROM. Conclusions: The presence of low AFI supports the diagnosis of PPROM. ROC curve analysis revealed that an AFI <= 10 cm is the optimal cut-off value in the suspicion of PPROM.