Cervical length for the prediction and prevention of preterm birth

The risk of early birth increases markedly with decreasing cervical length (CL) in both singleton and multiple pregnancies. Transvaginal ultrasound of CL can be useful in determining women that are at risk of preterm delivery and may be helpful in preventing unnecessary intervention. Appropriate technique is essential for correct results. Factors that affect the value of CL in the prediction of spontaneous preterm delivery include gestational age, patient obstetrical and medical history, symptoms and the number of fetuses. The value of CL consists of identifying high-risk women for therapeutic strategies, to reduce the rate of spontaneous preterm birth, such as progestogens, cervical cerclage and more recently, cervical pessary. Progestogens and cervical cerclage are more effective in gestations with prior preterm birth.