Abstract
In the last decade, transvaginal ultrasound for visualization of the cervix has become an important tool in obstetric antenatal care. The measurement of cervical length at 22-24 weeks of gestation provides useful prediction of the risk of subsequent spontaneous preterm delivery.
In low-risk pregnancies, both cervical measurement and fetal fibronectin screening have low sensitivity for preterm birth in asymptomatic women when used independently or in combination. In high-risk singleton gestations because of obsteric history a cervical length of less than 25 mm is more predictive of preterm birth.
In patients with symptoms of preterm labor, cervical sonography and fetal fibronectin testing appears to be effective predictor of preterm delivery within 7 days of presentation.