Transvaginal ultrasonographic measurement of cervical length in predicting intra-amniotic infection and impending preterm delivery in preterm labor: a comparison with amniotic fluid white blood cell count

Aims: To determine whether sonographic measurement of cervical length predicts intra-amniotic infection and impending preterm delivery (within 7 days of amniocentesis) in women with preterm labor and intact membranes, and to compare the predictability with that of amniotic fluid (AF) white blood cell (WBC) count. Methods: Transvaginal ultrasonographic assessment of cervical length was performed immediately after amniocentesis in 67 consecutive women with preterm labor. AF obtained by amniocentesis was cultured for aerobic and anaerobic bacteria and for Mycoplasmas, and WBC count was determined. Results: Patients with a positive AF culture had a significantly shorter median cervical length, higher median AF WBC count, and lower median gestational age at delivery than did those with a negative AF culture. Multivariate analysis indicated that only the AF WBC count bears a significant relationship with the presence of intra-amniotic infection, whereas only cervical length correlates with impending preterm delivery. Conclusions: Transvaginal sonographic measurements of cervical length are a valuable method for predicting intra-amniotic infection as well as impending preterm delivery in women with preterm labor. However, in comparison with AF WBC, cervical length is less predictive for intra-amniotic infection, whereas cervical length demonstrates better predictability of impending preterm delivery.