Prediction of imminent preterm delivery in women with preterm premature rupture of membranes

Aims: To develop a model based on non-invasive clinical parameters to predict the probability of imminent preterm delivery (delivery within 48 h) in women with preterm premature rupture of membranes (PPROM), and to determine if additional invasive test results improve the prediction of imminent delivery based on the non-invasive model. Methods: Transvaginal ultrasonographic assessment of cervical length was performed and maternal serum C-reactive protein (CRP) and white blood cell (WBC) count were determined immediately after amniocentesis in 102 consecutive women with PPROM at 23-33+6 weeks. Amniotic fluid (AF) obtained by amniocentesis was cultured and interleukin-6 (IL-6) levels and WBC counts were determined. Results: Serum CRP, cervical length, and gestational age were chosen for the non-invasive model (model 1), which has an area under the curve (AUC) of 0.804. When adding AF IL-6 as an invasive marker to the non-invasive model, serum CRP was excluded from the final model (model 2) as not significant, whereas AF IL-6, cervical length, and gestational age remained in model 2. No significant difference in AUC was found between models 1 and 2. Conclusions: The non-invasive model based on cervical length, gestational age, and serum CRP is highly predictive of imminent delivery in women with PPROM. However, invasive test results did not add predictive information to the non-invasive model in this setting.