Sonographic assessment of cervical length and the risk of preterm birth.

Sonographic assessment of cervical length is useful in evaluating the risk of preterm birth. Ultrasound is more accurate than digital exam and can be used in conjunction with fetal fibronectin (fFN) testing. Documentation of a long cervical length can reduce unnecessary treatments and hospitalizations in women who are unlikely to give birth preterm. Short cervical length can promote prompt intervention. Recognition of normal sonographic anatomy and proper measurement of the cervical canal are required.