Ultrasound diagnosis of the cervix for prediction of preterm delivery

It is difficult to identify correctly those pregnant women who have an increased risk for preterm delivery with traditional diagnostic tools. The measurement of cervical length and dilatation of the internal os by transvaginal ultrasound provide simple parameters with effective results. First, the correct method of measurement is described. Together with a literature review the sensitivity, specificity, positive and negative predictive value are discussed for pregnant women without a risk factor, those with preterm labor, or repeated preterm delivery and multiple pregnancies. The fetal fibronectin test, assessment of bacterial vaginosis, and cervical measurement are currently the best markers for the risk of preterm delivery.