Validity of amniotic fluid index in preterm rupture of membranes

Preterm premature rupture of membranes (pPROM) complicates up to one-third of preterm deliveries. We studied the Amniotic Fluid Index (AFI) in order to ascertain its validity as a predictive variable of maternal-fetal outcome in pregnancies complicated by pPROM. One hundred and fourteen pregnant women with gestational age between 24 and 34 weeks' gestation at the time of pPROM. Patients were categorized into two groups on the basis of AFI value (AFI <5 cm=63 or AFI >or=5 cm=51) performed at the time of admission. AFI numeric values were significantly related to the following maternal-neonatal variables: high maternal body temperature (P<or=0.001), maternal high white blood cells (WBC) count (P<or=0.001) and to Apgar score >7 at 5 min (P<or=0.001). No other significant correlation between the AFI score and others variables (i.e., maternal heart rate, neonatal WBC count or neonatal C-reactive protein [CRP]) were found. Latency in days from pPROM was significantly lower in the group with AFI <5 cm (P<0.05). Interestingly, AFI <5 cm was present in 66% of pregnancies complicated by chorioamnionitis (8/12), and in 70% of neonates affected by RDS at birth (19/27). An AFI score <5 cm at admission may be a useful prognostic variable in the management of third trimester pregnancies affected by pPROM.