Predicting preterm delivery in asymptomatic patients with prior preterm delivery by measurement of cervical length and phosphorylated insulin-like growth factor-binding protein-1

Objective To evaluate the efficacy of cervical length measurement in combination with a bedside assessment of phosphorylated insulin-like growth factor-binding protein-1 (phIGFBP-1) as a predictor of preterm delivery in asymptomatic pregnant women with a history of preterm birth. Methods Cervical length was measured using transvaginal sonography at 22-24 weeks o f gestation in 105 singleton pregnancies and a rapid strip test was performed to detect phIGFBP-1 in cervical secretions from 24 to 34 weeks. Receiver-operating characteristics (ROC) curves were constructed to compare the performance of phIGFBP-1 at different gestational ages, and cervical length at 22-24 weeks, in predicting preterm delivery. Results The rate of spontaneous delivery before 37 and 34 weeks was 23.8% and 11.4%, respectively. Women with cervical lengths less than 20 mm had a risk o f spontaneous preterm delivery before 34 and 37 weeks of 43.5% and 69.6%, respectively. The performance o f phIGFBP-1 levels as a predictor o f preterm delivery was significantly higher when the test was carried out at 30 weeks' gestation. Cervical assessment in combination with pbIGFBP-1 at 30 weeks had the steepest ROC curve (area under the curve = 0.93; 95% CI, 0.88-0.98, P < 0.001). Conclusion Both cervical length and phIGFBP-1 measurement are useful in the prediction o f preterm delivery in patients with a history o f preterm birth and the combined method o f measuring cervical length at 22-24 weeks and phIGFBP-1 at 30 weeks improves upon either method used alone. Copyright (c) 2007 ISUOG. Published by John Wiley & Sons, Ltd.